diff --git a/Cargo.lock b/Cargo.lock
index 7d2fca8bb3f48..1537a60718623 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4499,7 +4499,10 @@ dependencies = [
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",
+ "serde",
+ "serde_derive",
  "serde_json",
+ "serde_path_to_error",
  "tracing",
 ]
 
@@ -4870,6 +4873,16 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_path_to_error"
+version = "0.1.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59fab13f937fa393d08645bf3a84bdfe86e296747b506ada67bb15f10f218b2a"
+dependencies = [
+ "itoa",
+ "serde",
+]
+
 [[package]]
 name = "serde_spanned"
 version = "0.6.9"
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index d6215e1de043a..190cb6c5e0388 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -336,12 +336,12 @@ impl LinkSelfContained {
         if let Some(component_to_enable) = component.strip_prefix('+') {
             self.explicitly_set = None;
             self.enabled_components
-                .insert(LinkSelfContainedComponents::from_str(component_to_enable)?);
+                .insert(LinkSelfContainedComponents::from_str(component_to_enable).ok()?);
             Some(())
         } else if let Some(component_to_disable) = component.strip_prefix('-') {
             self.explicitly_set = None;
             self.disabled_components
-                .insert(LinkSelfContainedComponents::from_str(component_to_disable)?);
+                .insert(LinkSelfContainedComponents::from_str(component_to_disable).ok()?);
             Some(())
         } else {
             None
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 2bdde2f887a30..313eec6268d3c 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1295,7 +1295,7 @@ pub mod parse {
     }
 
     pub(crate) fn parse_linker_flavor(slot: &mut Option<LinkerFlavorCli>, v: Option<&str>) -> bool {
-        match v.and_then(LinkerFlavorCli::from_str) {
+        match v.and_then(|v| LinkerFlavorCli::from_str(v).ok()) {
             Some(lf) => *slot = Some(lf),
             _ => return false,
         }
diff --git a/compiler/rustc_target/Cargo.toml b/compiler/rustc_target/Cargo.toml
index 0121c752dbdde..56932c24922e5 100644
--- a/compiler/rustc_target/Cargo.toml
+++ b/compiler/rustc_target/Cargo.toml
@@ -12,7 +12,10 @@ rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
+serde = "1.0.219"
+serde_derive = "1.0.219"
 serde_json = "1.0.59"
+serde_path_to_error = "0.1.17"
 tracing = "0.1"
 # tidy-alphabetical-end
 
diff --git a/compiler/rustc_target/src/json.rs b/compiler/rustc_target/src/json.rs
index 4fcc477921ba2..896609bdbe3a7 100644
--- a/compiler/rustc_target/src/json.rs
+++ b/compiler/rustc_target/src/json.rs
@@ -114,3 +114,18 @@ impl ToJson for rustc_abi::CanonAbi {
         self.to_string().to_json()
     }
 }
+
+macro_rules! serde_deserialize_from_str {
+    ($ty:ty) => {
+        impl<'de> serde::Deserialize<'de> for $ty {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: serde::Deserializer<'de>,
+            {
+                let s = String::deserialize(deserializer)?;
+                FromStr::from_str(&s).map_err(serde::de::Error::custom)
+            }
+        }
+    };
+}
+pub(crate) use serde_deserialize_from_str;
diff --git a/compiler/rustc_target/src/spec/json.rs b/compiler/rustc_target/src/spec/json.rs
index 6c716f8712530..d27c1929aef74 100644
--- a/compiler/rustc_target/src/spec/json.rs
+++ b/compiler/rustc_target/src/spec/json.rs
@@ -1,60 +1,47 @@
-use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::str::FromStr;
 
-use rustc_abi::{Align, AlignFromBytesError, ExternAbi};
-use serde_json::Value;
+use rustc_abi::{Align, AlignFromBytesError};
 
-use super::{Target, TargetKind, TargetOptions, TargetWarnings};
+use super::crt_objects::CrtObjects;
+use super::{
+    BinaryFormat, CodeModel, DebuginfoKind, FloatAbi, FramePointer, LinkArgsCli,
+    LinkSelfContainedComponents, LinkSelfContainedDefault, LinkerFlavorCli, LldFlavor,
+    MergeFunctions, PanicStrategy, RelocModel, RelroLevel, RustcAbi, SanitizerSet,
+    SmallDataThresholdSupport, SplitDebuginfo, StackProbeType, StaticCow, SymbolVisibility, Target,
+    TargetKind, TargetOptions, TargetWarnings, TlsModel,
+};
 use crate::json::{Json, ToJson};
 use crate::spec::AbiMap;
 
 impl Target {
     /// Loads a target descriptor from a JSON object.
-    pub fn from_json(obj: Json) -> Result<(Target, TargetWarnings), String> {
-        // While ugly, this code must remain this way to retain
-        // compatibility with existing JSON fields and the internal
-        // expected naming of the Target and TargetOptions structs.
-        // To ensure compatibility is retained, the built-in targets
-        // are round-tripped through this code to catch cases where
-        // the JSON parser is not updated to match the structs.
-
-        let mut obj = match obj {
-            Value::Object(obj) => obj,
-            _ => return Err("Expected JSON object for target")?,
-        };
+    pub fn from_json(json: &str) -> Result<(Target, TargetWarnings), String> {
+        let json_deserializer = &mut serde_json::Deserializer::from_str(json);
 
-        let mut get_req_field = |name: &str| {
-            obj.remove(name)
-                .and_then(|j| j.as_str().map(str::to_string))
-                .ok_or_else(|| format!("Field {name} in target specification is required"))
-        };
+        let json: TargetSpecJson =
+            serde_path_to_error::deserialize(json_deserializer).map_err(|err| err.to_string())?;
 
         let mut base = Target {
-            llvm_target: get_req_field("llvm-target")?.into(),
+            llvm_target: json.llvm_target,
             metadata: Default::default(),
-            pointer_width: get_req_field("target-pointer-width")?
-                .parse::<u32>()
-                .map_err(|_| "target-pointer-width must be an integer".to_string())?,
-            data_layout: get_req_field("data-layout")?.into(),
-            arch: get_req_field("arch")?.into(),
+            pointer_width: json
+                .target_pointer_width
+                .parse()
+                .map_err(|err| format!("invalid target-pointer-width: {err}"))?,
+            data_layout: json.data_layout,
+            arch: json.arch,
             options: Default::default(),
         };
 
         // FIXME: This doesn't properly validate anything and just ignores the data if it's invalid.
         // That's okay for now, the only use of this is when generating docs, which we don't do for
         // custom targets.
-        if let Some(Json::Object(mut metadata)) = obj.remove("metadata") {
-            base.metadata.description = metadata
-                .remove("description")
-                .and_then(|desc| desc.as_str().map(|desc| desc.to_owned().into()));
-            base.metadata.tier = metadata
-                .remove("tier")
-                .and_then(|tier| tier.as_u64())
-                .filter(|tier| (1..=3).contains(tier));
-            base.metadata.host_tools =
-                metadata.remove("host_tools").and_then(|host| host.as_bool());
-            base.metadata.std = metadata.remove("std").and_then(|host| host.as_bool());
+        if let Some(metadata) = json.metadata {
+            base.metadata.description = metadata.description;
+            base.metadata.tier = metadata.tier.filter(|tier| (1..=3).contains(tier));
+            base.metadata.host_tools = metadata.host_tools;
+            base.metadata.std = metadata.std;
         }
 
         let alignment_error = |field_name: &str, error: AlignFromBytesError| -> String {
@@ -65,640 +52,188 @@ impl Target {
             format!("`{}` bits is not a valid value for {field_name}: {msg}", error.align() * 8)
         };
 
-        let mut incorrect_type = vec![];
-
-        macro_rules! key {
-            ($key_name:ident) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|s| s.as_str().map(str::to_string).map(Cow::from)) {
-                    base.$key_name = s;
-                }
-            } );
-            ($key_name:ident = $json_name:expr) => ( {
-                let name = $json_name;
-                if let Some(s) = obj.remove(name).and_then(|s| s.as_str().map(str::to_string).map(Cow::from)) {
-                    base.$key_name = s;
-                }
-            } );
-            ($key_name:ident = $json_name:expr, u64 as $int_ty:ty) => ( {
-                let name = $json_name;
-                if let Some(s) = obj.remove(name).and_then(|b| b.as_u64()) {
-                    base.$key_name = s as $int_ty;
-                }
-            } );
-            ($key_name:ident, bool) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|b| b.as_bool()) {
-                    base.$key_name = s;
-                }
-            } );
-            ($key_name:ident = $json_name:expr, bool) => ( {
-                let name = $json_name;
-                if let Some(s) = obj.remove(name).and_then(|b| b.as_bool()) {
-                    base.$key_name = s;
-                }
-            } );
-            ($key_name:ident, u32) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|b| b.as_u64()) {
-                    if s < 1 || s > 5 {
-                        return Err("Not a valid DWARF version number".into());
-                    }
-                    base.$key_name = s as u32;
-                }
-            } );
-            ($key_name:ident, Option<bool>) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|b| b.as_bool()) {
-                    base.$key_name = Some(s);
-                }
-            } );
-            ($key_name:ident, Option<u64>) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|b| b.as_u64()) {
-                    base.$key_name = Some(s);
-                }
-            } );
-            ($key_name:ident, Option<StaticCow<str>>) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(s) = obj.remove(&name).and_then(|b| Some(b.as_str()?.to_string())) {
-                    base.$key_name = Some(s.into());
-                }
-            } );
-            ($key_name:ident, Option<Align>) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(b) = obj.remove(&name).and_then(|b| b.as_u64()) {
-                    match Align::from_bits(b) {
-                        Ok(align) => base.$key_name = Some(align),
-                        Err(e) => return Err(alignment_error(&name, e)),
-                    }
-                }
-            } );
-            ($key_name:ident, BinaryFormat) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|f| f.as_str().and_then(|s| {
-                    match s.parse::<super::BinaryFormat>() {
-                        Ok(binary_format) => base.$key_name = binary_format,
-                        _ => return Some(Err(format!(
-                            "'{s}' is not a valid value for binary_format. \
-                            Use 'coff', 'elf', 'mach-o', 'wasm' or 'xcoff' "
-                        ))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, MergeFunctions) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::MergeFunctions>() {
-                        Ok(mergefunc) => base.$key_name = mergefunc,
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      merge-functions. Use 'disabled', \
-                                                      'trampolines', or 'aliases'.",
-                                                      s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, FloatAbi) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::FloatAbi>() {
-                        Ok(float_abi) => base.$key_name = Some(float_abi),
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      llvm-floatabi. Use 'soft' or 'hard'.",
-                                                      s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, RustcAbi) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::RustcAbi>() {
-                        Ok(rustc_abi) => base.$key_name = Some(rustc_abi),
-                        _ => return Some(Err(format!(
-                            "'{s}' is not a valid value for rustc-abi. \
-                            Use 'x86-softfloat' or leave the field unset."
-                        ))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, RelocModel) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::RelocModel>() {
-                        Ok(relocation_model) => base.$key_name = relocation_model,
-                        _ => return Some(Err(format!("'{}' is not a valid relocation model. \
-                                                      Run `rustc --print relocation-models` to \
-                                                      see the list of supported values.", s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, CodeModel) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::CodeModel>() {
-                        Ok(code_model) => base.$key_name = Some(code_model),
-                        _ => return Some(Err(format!("'{}' is not a valid code model. \
-                                                      Run `rustc --print code-models` to \
-                                                      see the list of supported values.", s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, TlsModel) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::TlsModel>() {
-                        Ok(tls_model) => base.$key_name = tls_model,
-                        _ => return Some(Err(format!("'{}' is not a valid TLS model. \
-                                                      Run `rustc --print tls-models` to \
-                                                      see the list of supported values.", s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, SmallDataThresholdSupport) => ( {
-                obj.remove("small-data-threshold-support").and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::SmallDataThresholdSupport>() {
-                        Ok(support) => base.small_data_threshold_support = support,
-                        _ => return Some(Err(format!("'{s}' is not a valid value for small-data-threshold-support."))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, PanicStrategy) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s {
-                        "unwind" => base.$key_name = super::PanicStrategy::Unwind,
-                        "abort" => base.$key_name = super::PanicStrategy::Abort,
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      panic-strategy. Use 'unwind' or 'abort'.",
-                                                     s))),
-                }
-                Some(Ok(()))
-            })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, RelroLevel) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::RelroLevel>() {
-                        Ok(level) => base.$key_name = level,
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      relro-level. Use 'full', 'partial, or 'off'.",
-                                                      s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, Option<SymbolVisibility>) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::SymbolVisibility>() {
-                        Ok(level) => base.$key_name = Some(level),
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      symbol-visibility. Use 'hidden', 'protected, or 'interposable'.",
-                                                      s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, DebuginfoKind) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::DebuginfoKind>() {
-                        Ok(level) => base.$key_name = level,
-                        _ => return Some(Err(
-                            format!("'{s}' is not a valid value for debuginfo-kind. Use 'dwarf', \
-                                  'dwarf-dsym' or 'pdb'.")
-                        )),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, SplitDebuginfo) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::SplitDebuginfo>() {
-                        Ok(level) => base.$key_name = level,
-                        _ => return Some(Err(format!("'{}' is not a valid value for \
-                                                      split-debuginfo. Use 'off' or 'dsymutil'.",
-                                                      s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, list) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(j) = obj.remove(&name) {
-                    if let Some(v) = j.as_array() {
-                        base.$key_name = v.iter()
-                            .map(|a| a.as_str().unwrap().to_string().into())
-                            .collect();
-                    } else {
-                        incorrect_type.push(name)
-                    }
-                }
-            } );
-            ($key_name:ident, opt_list) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(j) = obj.remove(&name) {
-                    if let Some(v) = j.as_array() {
-                        base.$key_name = Some(v.iter()
-                            .map(|a| a.as_str().unwrap().to_string().into())
-                            .collect());
-                    } else {
-                        incorrect_type.push(name)
-                    }
+        macro_rules! forward {
+            ($name:ident) => {
+                if let Some($name) = json.$name {
+                    base.$name = $name;
                 }
-            } );
-            ($key_name:ident, fallible_list) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|j| {
-                    if let Some(v) = j.as_array() {
-                        match v.iter().map(|a| FromStr::from_str(a.as_str().unwrap())).collect() {
-                            Ok(l) => { base.$key_name = l },
-                            // FIXME: `fallible_list` can't re-use the `key!` macro for list
-                            // elements and the error messages from that macro, so it has a bad
-                            // generic message instead
-                            Err(_) => return Some(Err(
-                                format!("`{:?}` is not a valid value for `{}`", j, name)
-                            )),
-                        }
-                    } else {
-                        incorrect_type.push(name)
-                    }
-                    Some(Ok(()))
-                }).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, optional) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(o) = obj.remove(&name) {
-                    base.$key_name = o
-                        .as_str()
-                        .map(|s| s.to_string().into());
-                }
-            } );
-            ($key_name:ident = $json_name:expr, LldFlavor) => ( {
-                let name = $json_name;
-                obj.remove(name).and_then(|o| o.as_str().and_then(|s| {
-                    if let Some(flavor) = super::LldFlavor::from_str(&s) {
-                        base.$key_name = flavor;
-                    } else {
-                        return Some(Err(format!(
-                            "'{}' is not a valid value for lld-flavor. \
-                             Use 'darwin', 'gnu', 'link' or 'wasm'.",
-                            s)))
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident = $json_name:expr, LinkerFlavorCli) => ( {
-                let name = $json_name;
-                obj.remove(name).and_then(|o| o.as_str().and_then(|s| {
-                    match super::LinkerFlavorCli::from_str(s) {
-                        Some(linker_flavor) => base.$key_name = linker_flavor,
-                        _ => return Some(Err(format!("'{}' is not a valid value for linker-flavor. \
-                                                      Use {}", s, super::LinkerFlavorCli::one_of()))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, StackProbeType) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                obj.remove(&name).and_then(|o| match super::StackProbeType::from_json(&o) {
-                    Ok(v) => {
-                        base.$key_name = v;
-                        Some(Ok(()))
-                    },
-                    Err(s) => Some(Err(
-                        format!("`{:?}` is not a valid value for `{}`: {}", o, name, s)
-                    )),
-                }).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident, SanitizerSet) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(o) = obj.remove(&name) {
-                    if let Some(a) = o.as_array() {
-                        for s in a {
-                            use super::SanitizerSet;
-                            base.$key_name |= match s.as_str() {
-                                Some("address") => SanitizerSet::ADDRESS,
-                                Some("cfi") => SanitizerSet::CFI,
-                                Some("dataflow") => SanitizerSet::DATAFLOW,
-                                Some("kcfi") => SanitizerSet::KCFI,
-                                Some("kernel-address") => SanitizerSet::KERNELADDRESS,
-                                Some("leak") => SanitizerSet::LEAK,
-                                Some("memory") => SanitizerSet::MEMORY,
-                                Some("memtag") => SanitizerSet::MEMTAG,
-                                Some("safestack") => SanitizerSet::SAFESTACK,
-                                Some("shadow-call-stack") => SanitizerSet::SHADOWCALLSTACK,
-                                Some("thread") => SanitizerSet::THREAD,
-                                Some("hwaddress") => SanitizerSet::HWADDRESS,
-                                Some(s) => return Err(format!("unknown sanitizer {}", s)),
-                                _ => return Err(format!("not a string: {:?}", s)),
-                            };
-                        }
-                    } else {
-                        incorrect_type.push(name)
-                    }
-                }
-                Ok::<(), String>(())
-            } );
-            ($key_name:ident, link_self_contained_components) => ( {
-                // Skeleton of what needs to be parsed:
-                //
-                // ```
-                // $name: {
-                //     "components": [
-                //         <array of strings>
-                //     ]
-                // }
-                // ```
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(o) = obj.remove(&name) {
-                    if let Some(o) = o.as_object() {
-                        let component_array = o.get("components")
-                            .ok_or_else(|| format!("{name}: expected a \
-                                JSON object with a `components` field."))?;
-                        let component_array = component_array.as_array()
-                            .ok_or_else(|| format!("{name}.components: expected a JSON array"))?;
-                        let mut components = super::LinkSelfContainedComponents::empty();
-                        for s in component_array {
-                            components |= match s.as_str() {
-                                Some(s) => {
-                                    super::LinkSelfContainedComponents::from_str(s)
-                                        .ok_or_else(|| format!("unknown \
-                                        `-Clink-self-contained` component: {s}"))?
-                                },
-                                _ => return Err(format!("not a string: {:?}", s)),
-                            };
-                        }
-                        base.$key_name = super::LinkSelfContainedDefault::WithComponents(components);
-                    } else {
-                        incorrect_type.push(name)
-                    }
-                }
-                Ok::<(), String>(())
-            } );
-            ($key_name:ident = $json_name:expr, link_self_contained_backwards_compatible) => ( {
-                let name = $json_name;
-                obj.remove(name).and_then(|o| o.as_str().and_then(|s| {
-                    match s.parse::<super::LinkSelfContainedDefault>() {
-                        Ok(lsc_default) => base.$key_name = lsc_default,
-                        _ => return Some(Err(format!("'{}' is not a valid `-Clink-self-contained` default. \
-                                                      Use 'false', 'true', 'musl' or 'mingw'", s))),
-                    }
-                    Some(Ok(()))
-                })).unwrap_or(Ok(()))
-            } );
-            ($key_name:ident = $json_name:expr, link_objects) => ( {
-                let name = $json_name;
-                if let Some(val) = obj.remove(name) {
-                    let obj = val.as_object().ok_or_else(|| format!("{}: expected a \
-                        JSON object with fields per CRT object kind.", name))?;
-                    let mut args = super::CrtObjects::new();
-                    for (k, v) in obj {
-                        let kind = super::LinkOutputKind::from_str(&k).ok_or_else(|| {
-                            format!("{}: '{}' is not a valid value for CRT object kind. \
-                                     Use '(dynamic,static)-(nopic,pic)-exe' or \
-                                     '(dynamic,static)-dylib' or 'wasi-reactor-exe'", name, k)
-                        })?;
-
-                        let v = v.as_array().ok_or_else(||
-                            format!("{}.{}: expected a JSON array", name, k)
-                        )?.iter().enumerate()
-                            .map(|(i,s)| {
-                                let s = s.as_str().ok_or_else(||
-                                    format!("{}.{}[{}]: expected a JSON string", name, k, i))?;
-                                Ok(s.to_string().into())
-                            })
-                            .collect::<Result<Vec<_>, String>>()?;
-
-                        args.insert(kind, v);
-                    }
-                    base.$key_name = args;
-                }
-            } );
-            ($key_name:ident = $json_name:expr, link_args) => ( {
-                let name = $json_name;
-                if let Some(val) = obj.remove(name) {
-                    let obj = val.as_object().ok_or_else(|| format!("{}: expected a \
-                        JSON object with fields per linker-flavor.", name))?;
-                    let mut args = super::LinkArgsCli::new();
-                    for (k, v) in obj {
-                        let flavor = super::LinkerFlavorCli::from_str(&k).ok_or_else(|| {
-                            format!("{}: '{}' is not a valid value for linker-flavor. \
-                                     Use 'em', 'gcc', 'ld' or 'msvc'", name, k)
-                        })?;
-
-                        let v = v.as_array().ok_or_else(||
-                            format!("{}.{}: expected a JSON array", name, k)
-                        )?.iter().enumerate()
-                            .map(|(i,s)| {
-                                let s = s.as_str().ok_or_else(||
-                                    format!("{}.{}[{}]: expected a JSON string", name, k, i))?;
-                                Ok(s.to_string().into())
-                            })
-                            .collect::<Result<Vec<_>, String>>()?;
-
-                        args.insert(flavor, v);
-                    }
-                    base.$key_name = args;
-                }
-            } );
-            ($key_name:ident, env) => ( {
-                let name = (stringify!($key_name)).replace("_", "-");
-                if let Some(o) = obj.remove(&name) {
-                    if let Some(a) = o.as_array() {
-                        for o in a {
-                            if let Some(s) = o.as_str() {
-                                if let [k, v] = *s.split('=').collect::<Vec<_>>() {
-                                    base.$key_name
-                                        .to_mut()
-                                        .push((k.to_string().into(), v.to_string().into()))
-                                }
-                            }
-                        }
-                    } else {
-                        incorrect_type.push(name)
-                    }
+            };
+        }
+        macro_rules! forward_opt {
+            ($name:ident) => {
+                if let Some($name) = json.$name {
+                    base.$name = Some($name);
                 }
-            } );
-            ($key_name:ident, target_families) => ( {
-                if let Some(value) = obj.remove("target-family") {
-                    if let Some(v) = value.as_array() {
-                        base.$key_name = v.iter()
-                            .map(|a| a.as_str().unwrap().to_string().into())
-                            .collect();
-                    } else if let Some(v) = value.as_str() {
-                        base.$key_name = vec![v.to_string().into()].into();
-                    }
+            };
+        }
+
+        if let Some(target_endian) = json.target_endian {
+            base.endian = target_endian.0;
+        }
+
+        forward!(frame_pointer);
+        forward!(c_int_width);
+        forward_opt!(c_enum_min_bits); // if None, matches c_int_width
+        forward!(os);
+        forward!(env);
+        forward!(abi);
+        forward!(vendor);
+        forward_opt!(linker);
+        forward!(linker_flavor_json);
+        forward!(lld_flavor_json);
+        forward!(linker_is_gnu_json);
+        forward!(pre_link_objects);
+        forward!(post_link_objects);
+        forward!(pre_link_objects_self_contained);
+        forward!(post_link_objects_self_contained);
+
+        // Deserializes the backwards-compatible variants of `-Clink-self-contained`
+        if let Some(link_self_contained) = json.link_self_contained_backwards_compatible {
+            base.link_self_contained = link_self_contained;
+        }
+        // Deserializes the components variant of `-Clink-self-contained`
+        if let Some(link_self_contained) = json.link_self_contained {
+            let components = link_self_contained
+                .components
+                .into_iter()
+                .fold(LinkSelfContainedComponents::empty(), |a, b| a | b);
+            base.link_self_contained = LinkSelfContainedDefault::WithComponents(components);
+        }
+
+        forward!(pre_link_args_json);
+        forward!(late_link_args_json);
+        forward!(late_link_args_dynamic_json);
+        forward!(late_link_args_static_json);
+        forward!(post_link_args_json);
+        forward_opt!(link_script);
+
+        if let Some(link_env) = json.link_env {
+            for s in link_env {
+                if let [k, v] = *s.split('=').collect::<Vec<_>>() {
+                    base.link_env.to_mut().push((k.to_string().into(), v.to_string().into()))
+                } else {
+                    return Err(format!("link-env value '{s}' must be of the pattern 'KEY=VALUE'"));
                 }
-            } );
+            }
         }
 
-        if let Some(j) = obj.remove("target-endian") {
-            if let Some(s) = j.as_str() {
-                base.endian = s.parse()?;
-            } else {
-                incorrect_type.push("target-endian".into())
+        forward!(link_env_remove);
+        forward!(asm_args);
+        forward!(cpu);
+        forward!(need_explicit_cpu);
+        forward!(features);
+        forward!(dynamic_linking);
+        forward_opt!(direct_access_external_data);
+        forward!(dll_tls_export);
+        forward!(only_cdylib);
+        forward!(executables);
+        forward!(relocation_model);
+        forward_opt!(code_model);
+        forward!(tls_model);
+        forward!(disable_redzone);
+        forward!(function_sections);
+        forward!(dll_prefix);
+        forward!(dll_suffix);
+        forward!(exe_suffix);
+        forward!(staticlib_prefix);
+        forward!(staticlib_suffix);
+
+        if let Some(target_family) = json.target_family {
+            match target_family {
+                TargetFamiliesJson::Array(families) => base.families = families,
+                TargetFamiliesJson::String(family) => base.families = vec![family].into(),
             }
         }
 
-        if let Some(fp) = obj.remove("frame-pointer") {
-            if let Some(s) = fp.as_str() {
-                base.frame_pointer = s
-                    .parse()
-                    .map_err(|()| format!("'{s}' is not a valid value for frame-pointer"))?;
-            } else {
-                incorrect_type.push("frame-pointer".into())
+        forward!(abi_return_struct_as_int);
+        forward!(is_like_aix);
+        forward!(is_like_darwin);
+        forward!(is_like_solaris);
+        forward!(is_like_windows);
+        forward!(is_like_msvc);
+        forward!(is_like_wasm);
+        forward!(is_like_android);
+        forward!(binary_format);
+        forward!(default_dwarf_version);
+        forward!(allows_weak_linkage);
+        forward!(has_rpath);
+        forward!(no_default_libraries);
+        forward!(position_independent_executables);
+        forward!(static_position_independent_executables);
+        forward!(plt_by_default);
+        forward!(relro_level);
+        forward!(archive_format);
+        forward!(allow_asm);
+        forward!(main_needs_argc_argv);
+        forward!(has_thread_local);
+        forward!(obj_is_bitcode);
+        forward!(bitcode_llvm_cmdline);
+        forward_opt!(max_atomic_width);
+        forward_opt!(min_atomic_width);
+        forward!(atomic_cas);
+        forward!(panic_strategy);
+        forward!(crt_static_allows_dylibs);
+        forward!(crt_static_default);
+        forward!(crt_static_respected);
+        forward!(stack_probes);
+
+        if let Some(min_global_align) = json.min_global_align {
+            match Align::from_bits(min_global_align) {
+                Ok(align) => base.min_global_align = Some(align),
+                Err(e) => return Err(alignment_error("min-global-align", e)),
             }
         }
 
-        key!(c_int_width = "target-c-int-width", u64 as u16);
-        key!(c_enum_min_bits, Option<u64>); // if None, matches c_int_width
-        key!(os);
-        key!(env);
-        key!(abi);
-        key!(vendor);
-        key!(linker, optional);
-        key!(linker_flavor_json = "linker-flavor", LinkerFlavorCli)?;
-        key!(lld_flavor_json = "lld-flavor", LldFlavor)?;
-        key!(linker_is_gnu_json = "linker-is-gnu", bool);
-        key!(pre_link_objects = "pre-link-objects", link_objects);
-        key!(post_link_objects = "post-link-objects", link_objects);
-        key!(pre_link_objects_self_contained = "pre-link-objects-fallback", link_objects);
-        key!(post_link_objects_self_contained = "post-link-objects-fallback", link_objects);
-        // Deserializes the backwards-compatible variants of `-Clink-self-contained`
-        key!(
-            link_self_contained = "crt-objects-fallback",
-            link_self_contained_backwards_compatible
-        )?;
-        // Deserializes the components variant of `-Clink-self-contained`
-        key!(link_self_contained, link_self_contained_components)?;
-        key!(pre_link_args_json = "pre-link-args", link_args);
-        key!(late_link_args_json = "late-link-args", link_args);
-        key!(late_link_args_dynamic_json = "late-link-args-dynamic", link_args);
-        key!(late_link_args_static_json = "late-link-args-static", link_args);
-        key!(post_link_args_json = "post-link-args", link_args);
-        key!(link_script, optional);
-        key!(link_env, env);
-        key!(link_env_remove, list);
-        key!(asm_args, list);
-        key!(cpu);
-        key!(need_explicit_cpu, bool);
-        key!(features);
-        key!(dynamic_linking, bool);
-        key!(direct_access_external_data, Option<bool>);
-        key!(dll_tls_export, bool);
-        key!(only_cdylib, bool);
-        key!(executables, bool);
-        key!(relocation_model, RelocModel)?;
-        key!(code_model, CodeModel)?;
-        key!(tls_model, TlsModel)?;
-        key!(disable_redzone, bool);
-        key!(function_sections, bool);
-        key!(dll_prefix);
-        key!(dll_suffix);
-        key!(exe_suffix);
-        key!(staticlib_prefix);
-        key!(staticlib_suffix);
-        key!(families, target_families);
-        key!(abi_return_struct_as_int, bool);
-        key!(is_like_aix, bool);
-        key!(is_like_darwin, bool);
-        key!(is_like_solaris, bool);
-        key!(is_like_windows, bool);
-        key!(is_like_msvc, bool);
-        key!(is_like_wasm, bool);
-        key!(is_like_android, bool);
-        key!(binary_format, BinaryFormat)?;
-        key!(default_dwarf_version, u32);
-        key!(allows_weak_linkage, bool);
-        key!(has_rpath, bool);
-        key!(no_default_libraries, bool);
-        key!(position_independent_executables, bool);
-        key!(static_position_independent_executables, bool);
-        key!(plt_by_default, bool);
-        key!(relro_level, RelroLevel)?;
-        key!(archive_format);
-        key!(allow_asm, bool);
-        key!(main_needs_argc_argv, bool);
-        key!(has_thread_local, bool);
-        key!(obj_is_bitcode, bool);
-        key!(bitcode_llvm_cmdline);
-        key!(max_atomic_width, Option<u64>);
-        key!(min_atomic_width, Option<u64>);
-        key!(atomic_cas, bool);
-        key!(panic_strategy, PanicStrategy)?;
-        key!(crt_static_allows_dylibs, bool);
-        key!(crt_static_default, bool);
-        key!(crt_static_respected, bool);
-        key!(stack_probes, StackProbeType)?;
-        key!(min_global_align, Option<Align>);
-        key!(default_codegen_units, Option<u64>);
-        key!(default_codegen_backend, Option<StaticCow<str>>);
-        key!(trap_unreachable, bool);
-        key!(requires_lto, bool);
-        key!(singlethread, bool);
-        key!(no_builtins, bool);
-        key!(default_visibility, Option<SymbolVisibility>)?;
-        key!(emit_debug_gdb_scripts, bool);
-        key!(requires_uwtable, bool);
-        key!(default_uwtable, bool);
-        key!(simd_types_indirect, bool);
-        key!(limit_rdylib_exports, bool);
-        key!(override_export_symbols, opt_list);
-        key!(merge_functions, MergeFunctions)?;
-        key!(mcount = "target-mcount");
-        key!(llvm_mcount_intrinsic, optional);
-        key!(llvm_abiname);
-        key!(llvm_floatabi, FloatAbi)?;
-        key!(rustc_abi, RustcAbi)?;
-        key!(relax_elf_relocations, bool);
-        key!(llvm_args, list);
-        key!(use_ctors_section, bool);
-        key!(eh_frame_header, bool);
-        key!(has_thumb_interworking, bool);
-        key!(debuginfo_kind, DebuginfoKind)?;
-        key!(split_debuginfo, SplitDebuginfo)?;
-        key!(supported_split_debuginfo, fallible_list)?;
-        key!(supported_sanitizers, SanitizerSet)?;
-        key!(generate_arange_section, bool);
-        key!(supports_stack_protector, bool);
-        key!(small_data_threshold_support, SmallDataThresholdSupport)?;
-        key!(entry_name);
-        key!(supports_xray, bool);
+        forward_opt!(default_codegen_units);
+        forward_opt!(default_codegen_backend);
+        forward!(trap_unreachable);
+        forward!(requires_lto);
+        forward!(singlethread);
+        forward!(no_builtins);
+        forward_opt!(default_visibility);
+        forward!(emit_debug_gdb_scripts);
+        forward!(requires_uwtable);
+        forward!(default_uwtable);
+        forward!(simd_types_indirect);
+        forward!(limit_rdylib_exports);
+        forward_opt!(override_export_symbols);
+        forward!(merge_functions);
+        forward!(mcount);
+        forward_opt!(llvm_mcount_intrinsic);
+        forward!(llvm_abiname);
+        forward_opt!(llvm_floatabi);
+        forward_opt!(rustc_abi);
+        forward!(relax_elf_relocations);
+        forward!(llvm_args);
+        forward!(use_ctors_section);
+        forward!(eh_frame_header);
+        forward!(has_thumb_interworking);
+        forward!(debuginfo_kind);
+        forward!(split_debuginfo);
+        forward!(supported_split_debuginfo);
+
+        if let Some(supported_sanitizers) = json.supported_sanitizers {
+            base.supported_sanitizers =
+                supported_sanitizers.into_iter().fold(SanitizerSet::empty(), |a, b| a | b);
+        }
+
+        forward!(generate_arange_section);
+        forward!(supports_stack_protector);
+        forward!(small_data_threshold_support);
+        forward!(entry_name);
+        forward!(supports_xray);
 
         // we're going to run `update_from_cli`, but that won't change the target's AbiMap
         // FIXME: better factor the Target definition so we enforce this on a type level
         let abi_map = AbiMap::from_target(&base);
-
-        if let Some(abi_str) = obj.remove("entry-abi") {
-            if let Json::String(abi_str) = abi_str {
-                match abi_str.parse::<ExternAbi>() {
-                    Ok(abi) => base.options.entry_abi = abi_map.canonize_abi(abi, false).unwrap(),
-                    Err(_) => return Err(format!("{abi_str} is not a valid ExternAbi")),
-                }
-            } else {
-                incorrect_type.push("entry-abi".to_owned())
-            }
+        if let Some(entry_abi) = json.entry_abi {
+            base.options.entry_abi = abi_map.canonize_abi(entry_abi.0, false).unwrap();
         }
 
         base.update_from_cli();
         base.check_consistency(TargetKind::Json)?;
 
-        // Each field should have been read using `Json::remove` so any keys remaining are unused.
-        let remaining_keys = obj.keys();
-        Ok((
-            base,
-            TargetWarnings { unused_fields: remaining_keys.cloned().collect(), incorrect_type },
-        ))
+        Ok((base, TargetWarnings { unused_fields: vec![] }))
     }
 }
 
@@ -877,3 +412,189 @@ impl ToJson for Target {
         Json::Object(d)
     }
 }
+
+#[derive(serde_derive::Deserialize)]
+struct LinkSelfContainedComponentsWrapper {
+    components: Vec<LinkSelfContainedComponents>,
+}
+
+#[derive(serde_derive::Deserialize)]
+#[serde(untagged)]
+enum TargetFamiliesJson {
+    Array(StaticCow<[StaticCow<str>]>),
+    String(StaticCow<str>),
+}
+
+/// `Endian` is in `rustc_abi`, which doesn't have access to the macro and serde.
+struct EndianWrapper(rustc_abi::Endian);
+impl FromStr for EndianWrapper {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        rustc_abi::Endian::from_str(s).map(Self)
+    }
+}
+crate::json::serde_deserialize_from_str!(EndianWrapper);
+
+/// `ExternAbi` is in `rustc_abi`, which doesn't have access to the macro and serde.
+struct ExternAbiWrapper(rustc_abi::ExternAbi);
+impl FromStr for ExternAbiWrapper {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        rustc_abi::ExternAbi::from_str(s)
+            .map(Self)
+            .map_err(|_| format!("{s} is not a valid extern ABI"))
+    }
+}
+crate::json::serde_deserialize_from_str!(ExternAbiWrapper);
+
+#[derive(serde_derive::Deserialize)]
+struct TargetSpecJsonMetadata {
+    description: Option<StaticCow<str>>,
+    tier: Option<u64>,
+    host_tools: Option<bool>,
+    std: Option<bool>,
+}
+
+#[derive(serde_derive::Deserialize)]
+#[serde(rename_all = "kebab-case")]
+// Ensure that all unexpected fields get turned into errors.
+// This helps users stay up to date when the schema changes instead of silently
+// ignoring their old values.
+#[serde(deny_unknown_fields)]
+struct TargetSpecJson {
+    llvm_target: StaticCow<str>,
+    target_pointer_width: String,
+    data_layout: StaticCow<str>,
+    arch: StaticCow<str>,
+
+    metadata: Option<TargetSpecJsonMetadata>,
+
+    // options:
+    target_endian: Option<EndianWrapper>,
+    frame_pointer: Option<FramePointer>,
+    #[serde(rename = "target-c-int-width")]
+    c_int_width: Option<u16>,
+    c_enum_min_bits: Option<u64>,
+    os: Option<StaticCow<str>>,
+    env: Option<StaticCow<str>>,
+    abi: Option<StaticCow<str>>,
+    vendor: Option<StaticCow<str>>,
+    linker: Option<StaticCow<str>>,
+    #[serde(rename = "linker-flavor")]
+    linker_flavor_json: Option<LinkerFlavorCli>,
+    #[serde(rename = "lld-flavor")]
+    lld_flavor_json: Option<LldFlavor>,
+    #[serde(rename = "linker-is-gnu")]
+    linker_is_gnu_json: Option<bool>,
+    #[serde(rename = "pre-link-objects")]
+    pre_link_objects: Option<CrtObjects>,
+    #[serde(rename = "post-link-objects")]
+    post_link_objects: Option<CrtObjects>,
+    #[serde(rename = "pre-link-objects-fallback")]
+    pre_link_objects_self_contained: Option<CrtObjects>,
+    #[serde(rename = "post-link-objects-fallback")]
+    post_link_objects_self_contained: Option<CrtObjects>,
+    #[serde(rename = "crt-objects-fallback")]
+    link_self_contained_backwards_compatible: Option<LinkSelfContainedDefault>,
+    link_self_contained: Option<LinkSelfContainedComponentsWrapper>,
+    #[serde(rename = "pre-link-args")]
+    pre_link_args_json: Option<LinkArgsCli>,
+    #[serde(rename = "late-link-args")]
+    late_link_args_json: Option<LinkArgsCli>,
+    #[serde(rename = "late-link-args-dynamic")]
+    late_link_args_dynamic_json: Option<LinkArgsCli>,
+    #[serde(rename = "late-link-args-static")]
+    late_link_args_static_json: Option<LinkArgsCli>,
+    #[serde(rename = "post-link-args")]
+    post_link_args_json: Option<LinkArgsCli>,
+    link_script: Option<StaticCow<str>>,
+    link_env: Option<Vec<StaticCow<str>>>,
+    link_env_remove: Option<StaticCow<[StaticCow<str>]>>,
+    asm_args: Option<StaticCow<[StaticCow<str>]>>,
+    cpu: Option<StaticCow<str>>,
+    need_explicit_cpu: Option<bool>,
+    features: Option<StaticCow<str>>,
+    dynamic_linking: Option<bool>,
+    direct_access_external_data: Option<bool>,
+    dll_tls_export: Option<bool>,
+    only_cdylib: Option<bool>,
+    executables: Option<bool>,
+    relocation_model: Option<RelocModel>,
+    code_model: Option<CodeModel>,
+    tls_model: Option<TlsModel>,
+    disable_redzone: Option<bool>,
+    function_sections: Option<bool>,
+    dll_prefix: Option<StaticCow<str>>,
+    dll_suffix: Option<StaticCow<str>>,
+    exe_suffix: Option<StaticCow<str>>,
+    staticlib_prefix: Option<StaticCow<str>>,
+    staticlib_suffix: Option<StaticCow<str>>,
+    target_family: Option<TargetFamiliesJson>,
+    abi_return_struct_as_int: Option<bool>,
+    is_like_aix: Option<bool>,
+    is_like_darwin: Option<bool>,
+    is_like_solaris: Option<bool>,
+    is_like_windows: Option<bool>,
+    is_like_msvc: Option<bool>,
+    is_like_wasm: Option<bool>,
+    is_like_android: Option<bool>,
+    binary_format: Option<BinaryFormat>,
+    default_dwarf_version: Option<u32>,
+    allows_weak_linkage: Option<bool>,
+    has_rpath: Option<bool>,
+    no_default_libraries: Option<bool>,
+    position_independent_executables: Option<bool>,
+    static_position_independent_executables: Option<bool>,
+    plt_by_default: Option<bool>,
+    relro_level: Option<RelroLevel>,
+    archive_format: Option<StaticCow<str>>,
+    allow_asm: Option<bool>,
+    main_needs_argc_argv: Option<bool>,
+    has_thread_local: Option<bool>,
+    obj_is_bitcode: Option<bool>,
+    bitcode_llvm_cmdline: Option<StaticCow<str>>,
+    max_atomic_width: Option<u64>,
+    min_atomic_width: Option<u64>,
+    atomic_cas: Option<bool>,
+    panic_strategy: Option<PanicStrategy>,
+    crt_static_allows_dylibs: Option<bool>,
+    crt_static_default: Option<bool>,
+    crt_static_respected: Option<bool>,
+    stack_probes: Option<StackProbeType>,
+    min_global_align: Option<u64>,
+    default_codegen_units: Option<u64>,
+    default_codegen_backend: Option<StaticCow<str>>,
+    trap_unreachable: Option<bool>,
+    requires_lto: Option<bool>,
+    singlethread: Option<bool>,
+    no_builtins: Option<bool>,
+    default_visibility: Option<SymbolVisibility>,
+    emit_debug_gdb_scripts: Option<bool>,
+    requires_uwtable: Option<bool>,
+    default_uwtable: Option<bool>,
+    simd_types_indirect: Option<bool>,
+    limit_rdylib_exports: Option<bool>,
+    override_export_symbols: Option<StaticCow<[StaticCow<str>]>>,
+    merge_functions: Option<MergeFunctions>,
+    #[serde(rename = "target-mcount")]
+    mcount: Option<StaticCow<str>>,
+    llvm_mcount_intrinsic: Option<StaticCow<str>>,
+    llvm_abiname: Option<StaticCow<str>>,
+    llvm_floatabi: Option<FloatAbi>,
+    rustc_abi: Option<RustcAbi>,
+    relax_elf_relocations: Option<bool>,
+    llvm_args: Option<StaticCow<[StaticCow<str>]>>,
+    use_ctors_section: Option<bool>,
+    eh_frame_header: Option<bool>,
+    has_thumb_interworking: Option<bool>,
+    debuginfo_kind: Option<DebuginfoKind>,
+    split_debuginfo: Option<SplitDebuginfo>,
+    supported_split_debuginfo: Option<StaticCow<[SplitDebuginfo]>>,
+    supported_sanitizers: Option<Vec<SanitizerSet>>,
+    generate_arange_section: Option<bool>,
+    supports_stack_protector: Option<bool>,
+    small_data_threshold_support: Option<SmallDataThresholdSupport>,
+    entry_name: Option<StaticCow<str>>,
+    supports_xray: Option<bool>,
+    entry_abi: Option<ExternAbiWrapper>,
+}
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 4bc0d88a910cb..c64cd9a51b7d2 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -37,6 +37,7 @@
 //!
 //! [JSON]: https://json.org
 
+use core::result::Result;
 use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::hash::{Hash, Hasher};
@@ -198,18 +199,29 @@ impl LldFlavor {
             LldFlavor::Link => "link",
         }
     }
+}
 
-    fn from_str(s: &str) -> Option<Self> {
-        Some(match s {
+impl FromStr for LldFlavor {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
             "darwin" => LldFlavor::Ld64,
             "gnu" => LldFlavor::Ld,
             "link" => LldFlavor::Link,
             "wasm" => LldFlavor::Wasm,
-            _ => return None,
+            _ => {
+                return Err(
+                    "invalid value for lld flavor: '{s}', expected one of 'darwin', 'gnu', 'link', 'wasm'"
+                        .into(),
+                );
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(LldFlavor);
+
 impl ToJson for LldFlavor {
     fn to_json(&self) -> Json {
         self.as_str().to_json()
@@ -494,19 +506,23 @@ macro_rules! linker_flavor_cli_impls {
                 concat!("one of: ", $($string, " ",)*)
             }
 
-            pub fn from_str(s: &str) -> Option<LinkerFlavorCli> {
-                Some(match s {
-                    $($string => $($flavor)*,)*
-                    _ => return None,
-                })
-            }
-
             pub fn desc(self) -> &'static str {
                 match self {
                     $($($flavor)* => $string,)*
                 }
             }
         }
+
+        impl FromStr for LinkerFlavorCli {
+            type Err = String;
+
+            fn from_str(s: &str) -> Result<LinkerFlavorCli, Self::Err> {
+                Ok(match s {
+                    $($string => $($flavor)*,)*
+                    _ => return Err(format!("invalid linker flavor, allowed values: {}", Self::one_of())),
+                })
+            }
+        }
     )
 }
 
@@ -540,6 +556,8 @@ linker_flavor_cli_impls! {
     (LinkerFlavorCli::Em) "em"
 }
 
+crate::json::serde_deserialize_from_str!(LinkerFlavorCli);
+
 impl ToJson for LinkerFlavorCli {
     fn to_json(&self) -> Json {
         self.desc().to_json()
@@ -573,19 +591,26 @@ pub enum LinkSelfContainedDefault {
 
 /// Parses a backwards-compatible `-Clink-self-contained` option string, without components.
 impl FromStr for LinkSelfContainedDefault {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<LinkSelfContainedDefault, ()> {
+    fn from_str(s: &str) -> Result<LinkSelfContainedDefault, Self::Err> {
         Ok(match s {
             "false" => LinkSelfContainedDefault::False,
             "true" | "wasm" => LinkSelfContainedDefault::True,
             "musl" => LinkSelfContainedDefault::InferredForMusl,
             "mingw" => LinkSelfContainedDefault::InferredForMingw,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid `-Clink-self-contained` default. \
+                        Use 'false', 'true', 'wasm', 'musl' or 'mingw'",
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(LinkSelfContainedDefault);
+
 impl ToJson for LinkSelfContainedDefault {
     fn to_json(&self) -> Json {
         match *self {
@@ -652,19 +677,6 @@ bitflags::bitflags! {
 rustc_data_structures::external_bitflags_debug! { LinkSelfContainedComponents }
 
 impl LinkSelfContainedComponents {
-    /// Parses a single `-Clink-self-contained` well-known component, not a set of flags.
-    pub fn from_str(s: &str) -> Option<LinkSelfContainedComponents> {
-        Some(match s {
-            "crto" => LinkSelfContainedComponents::CRT_OBJECTS,
-            "libc" => LinkSelfContainedComponents::LIBC,
-            "unwind" => LinkSelfContainedComponents::UNWIND,
-            "linker" => LinkSelfContainedComponents::LINKER,
-            "sanitizers" => LinkSelfContainedComponents::SANITIZERS,
-            "mingw" => LinkSelfContainedComponents::MINGW,
-            _ => return None,
-        })
-    }
-
     /// Return the component's name.
     ///
     /// Returns `None` if the bitflags aren't a singular component (but a mix of multiple flags).
@@ -708,6 +720,29 @@ impl LinkSelfContainedComponents {
     }
 }
 
+impl FromStr for LinkSelfContainedComponents {
+    type Err = String;
+
+    /// Parses a single `-Clink-self-contained` well-known component, not a set of flags.
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "crto" => LinkSelfContainedComponents::CRT_OBJECTS,
+            "libc" => LinkSelfContainedComponents::LIBC,
+            "unwind" => LinkSelfContainedComponents::UNWIND,
+            "linker" => LinkSelfContainedComponents::LINKER,
+            "sanitizers" => LinkSelfContainedComponents::SANITIZERS,
+            "mingw" => LinkSelfContainedComponents::MINGW,
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid link-self-contained component, expected 'crto', 'libc', 'unwind', 'linker', 'sanitizers', 'mingw'"
+                ));
+            }
+        })
+    }
+}
+
+crate::json::serde_deserialize_from_str!(LinkSelfContainedComponents);
+
 impl ToJson for LinkSelfContainedComponents {
     fn to_json(&self) -> Json {
         let components: Vec<_> = Self::all_components()
@@ -821,6 +856,25 @@ impl PanicStrategy {
     }
 }
 
+impl FromStr for PanicStrategy {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "unwind" => PanicStrategy::Unwind,
+            "abort" => PanicStrategy::Abort,
+            _ => {
+                return Err(format!(
+                    "'{}' is not a valid value for \
+                    panic-strategy. Use 'unwind' or 'abort'.",
+                    s
+                ));
+            }
+        })
+    }
+}
+
+crate::json::serde_deserialize_from_str!(PanicStrategy);
+
 impl ToJson for PanicStrategy {
     fn to_json(&self) -> Json {
         match *self {
@@ -867,18 +921,24 @@ impl SymbolVisibility {
 }
 
 impl FromStr for SymbolVisibility {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<SymbolVisibility, ()> {
+    fn from_str(s: &str) -> Result<SymbolVisibility, Self::Err> {
         match s {
             "hidden" => Ok(SymbolVisibility::Hidden),
             "protected" => Ok(SymbolVisibility::Protected),
             "interposable" => Ok(SymbolVisibility::Interposable),
-            _ => Err(()),
+            _ => Err(format!(
+                "'{}' is not a valid value for \
+                    symbol-visibility. Use 'hidden', 'protected, or 'interposable'.",
+                s
+            )),
         }
     }
 }
 
+crate::json::serde_deserialize_from_str!(SymbolVisibility);
+
 impl ToJson for SymbolVisibility {
     fn to_json(&self) -> Json {
         match *self {
@@ -890,19 +950,25 @@ impl ToJson for SymbolVisibility {
 }
 
 impl FromStr for RelroLevel {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<RelroLevel, ()> {
+    fn from_str(s: &str) -> Result<RelroLevel, Self::Err> {
         match s {
             "full" => Ok(RelroLevel::Full),
             "partial" => Ok(RelroLevel::Partial),
             "off" => Ok(RelroLevel::Off),
             "none" => Ok(RelroLevel::None),
-            _ => Err(()),
+            _ => Err(format!(
+                "'{}' is not a valid value for \
+                        relro-level. Use 'full', 'partial, 'off', or 'none'.",
+                s
+            )),
         }
     }
 }
 
+crate::json::serde_deserialize_from_str!(RelroLevel);
+
 impl ToJson for RelroLevel {
     fn to_json(&self) -> Json {
         match *self {
@@ -923,7 +989,7 @@ pub enum SmallDataThresholdSupport {
 }
 
 impl FromStr for SmallDataThresholdSupport {
-    type Err = ();
+    type Err = String;
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         if s == "none" {
@@ -935,11 +1001,13 @@ impl FromStr for SmallDataThresholdSupport {
         } else if let Some(arg) = s.strip_prefix("llvm-arg=") {
             Ok(Self::LlvmArg(arg.to_string().into()))
         } else {
-            Err(())
+            Err(format!("'{s}' is not a valid value for small-data-threshold-support."))
         }
     }
 }
 
+crate::json::serde_deserialize_from_str!(SmallDataThresholdSupport);
+
 impl ToJson for SmallDataThresholdSupport {
     fn to_json(&self) -> Value {
         match self {
@@ -969,18 +1037,25 @@ impl MergeFunctions {
 }
 
 impl FromStr for MergeFunctions {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<MergeFunctions, ()> {
+    fn from_str(s: &str) -> Result<MergeFunctions, Self::Err> {
         match s {
             "disabled" => Ok(MergeFunctions::Disabled),
             "trampolines" => Ok(MergeFunctions::Trampolines),
             "aliases" => Ok(MergeFunctions::Aliases),
-            _ => Err(()),
+            _ => Err(format!(
+                "'{}' is not a valid value for \
+                    merge-functions. Use 'disabled', \
+                    'trampolines', or 'aliases'.",
+                s
+            )),
         }
     }
 }
 
+crate::json::serde_deserialize_from_str!(MergeFunctions);
+
 impl ToJson for MergeFunctions {
     fn to_json(&self) -> Json {
         match *self {
@@ -1040,9 +1115,9 @@ impl RelocModel {
 }
 
 impl FromStr for RelocModel {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<RelocModel, ()> {
+    fn from_str(s: &str) -> Result<RelocModel, Self::Err> {
         Ok(match s {
             "static" => RelocModel::Static,
             "pic" => RelocModel::Pic,
@@ -1051,11 +1126,19 @@ impl FromStr for RelocModel {
             "ropi" => RelocModel::Ropi,
             "rwpi" => RelocModel::Rwpi,
             "ropi-rwpi" => RelocModel::RopiRwpi,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "invalid relocation model '{s}'.
+                        Run `rustc --print relocation-models` to \
+                        see the list of supported values.'"
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(RelocModel);
+
 impl ToJson for RelocModel {
     fn to_json(&self) -> Json {
         self.desc().to_json()
@@ -1072,20 +1155,28 @@ pub enum CodeModel {
 }
 
 impl FromStr for CodeModel {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<CodeModel, ()> {
+    fn from_str(s: &str) -> Result<CodeModel, Self::Err> {
         Ok(match s {
             "tiny" => CodeModel::Tiny,
             "small" => CodeModel::Small,
             "kernel" => CodeModel::Kernel,
             "medium" => CodeModel::Medium,
             "large" => CodeModel::Large,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid code model. \
+                        Run `rustc --print code-models` to \
+                        see the list of supported values."
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(CodeModel);
+
 impl ToJson for CodeModel {
     fn to_json(&self) -> Json {
         match *self {
@@ -1107,17 +1198,25 @@ pub enum FloatAbi {
 }
 
 impl FromStr for FloatAbi {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<FloatAbi, ()> {
+    fn from_str(s: &str) -> Result<FloatAbi, Self::Err> {
         Ok(match s {
             "soft" => FloatAbi::Soft,
             "hard" => FloatAbi::Hard,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{}' is not a valid value for \
+                        llvm-floatabi. Use 'soft' or 'hard'.",
+                    s
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(FloatAbi);
+
 impl ToJson for FloatAbi {
     fn to_json(&self) -> Json {
         match *self {
@@ -1138,17 +1237,24 @@ pub enum RustcAbi {
 }
 
 impl FromStr for RustcAbi {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<RustcAbi, ()> {
+    fn from_str(s: &str) -> Result<RustcAbi, Self::Err> {
         Ok(match s {
             "x86-sse2" => RustcAbi::X86Sse2,
             "x86-softfloat" => RustcAbi::X86Softfloat,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid value for rustc-abi. \
+                        Use 'x86-softfloat' or leave the field unset."
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(RustcAbi);
+
 impl ToJson for RustcAbi {
     fn to_json(&self) -> Json {
         match *self {
@@ -1169,9 +1275,9 @@ pub enum TlsModel {
 }
 
 impl FromStr for TlsModel {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<TlsModel, ()> {
+    fn from_str(s: &str) -> Result<TlsModel, Self::Err> {
         Ok(match s {
             // Note the difference "general" vs "global" difference. The model name is "general",
             // but the user-facing option name is "global" for consistency with other compilers.
@@ -1180,11 +1286,19 @@ impl FromStr for TlsModel {
             "initial-exec" => TlsModel::InitialExec,
             "local-exec" => TlsModel::LocalExec,
             "emulated" => TlsModel::Emulated,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid TLS model. \
+                        Run `rustc --print tls-models` to \
+                        see the list of supported values."
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(TlsModel);
+
 impl ToJson for TlsModel {
     fn to_json(&self) -> Json {
         match *self {
@@ -1230,19 +1344,6 @@ impl LinkOutputKind {
         }
     }
 
-    pub(super) fn from_str(s: &str) -> Option<LinkOutputKind> {
-        Some(match s {
-            "dynamic-nopic-exe" => LinkOutputKind::DynamicNoPicExe,
-            "dynamic-pic-exe" => LinkOutputKind::DynamicPicExe,
-            "static-nopic-exe" => LinkOutputKind::StaticNoPicExe,
-            "static-pic-exe" => LinkOutputKind::StaticPicExe,
-            "dynamic-dylib" => LinkOutputKind::DynamicDylib,
-            "static-dylib" => LinkOutputKind::StaticDylib,
-            "wasi-reactor-exe" => LinkOutputKind::WasiReactorExe,
-            _ => return None,
-        })
-    }
-
     pub fn can_link_dylib(self) -> bool {
         match self {
             LinkOutputKind::StaticNoPicExe | LinkOutputKind::StaticPicExe => false,
@@ -1255,6 +1356,31 @@ impl LinkOutputKind {
     }
 }
 
+impl FromStr for LinkOutputKind {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<LinkOutputKind, Self::Err> {
+        Ok(match s {
+            "dynamic-nopic-exe" => LinkOutputKind::DynamicNoPicExe,
+            "dynamic-pic-exe" => LinkOutputKind::DynamicPicExe,
+            "static-nopic-exe" => LinkOutputKind::StaticNoPicExe,
+            "static-pic-exe" => LinkOutputKind::StaticPicExe,
+            "dynamic-dylib" => LinkOutputKind::DynamicDylib,
+            "static-dylib" => LinkOutputKind::StaticDylib,
+            "wasi-reactor-exe" => LinkOutputKind::WasiReactorExe,
+            _ => {
+                return Err(format!(
+                    "invalid value for CRT object kind. \
+                        Use '(dynamic,static)-(nopic,pic)-exe' or \
+                        '(dynamic,static)-dylib' or 'wasi-reactor-exe'"
+                ));
+            }
+        })
+    }
+}
+
+crate::json::serde_deserialize_from_str!(LinkOutputKind);
+
 impl fmt::Display for LinkOutputKind {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str(self.as_str())
@@ -1290,18 +1416,25 @@ impl DebuginfoKind {
 }
 
 impl FromStr for DebuginfoKind {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<Self, ()> {
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
         Ok(match s {
             "dwarf" => DebuginfoKind::Dwarf,
             "dwarf-dsym" => DebuginfoKind::DwarfDsym,
             "pdb" => DebuginfoKind::Pdb,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid value for debuginfo-kind. Use 'dwarf', \
+                        'dwarf-dsym' or 'pdb'."
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(DebuginfoKind);
+
 impl ToJson for DebuginfoKind {
     fn to_json(&self) -> Json {
         self.as_str().to_json()
@@ -1354,18 +1487,25 @@ impl SplitDebuginfo {
 }
 
 impl FromStr for SplitDebuginfo {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<Self, ()> {
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
         Ok(match s {
             "off" => SplitDebuginfo::Off,
             "unpacked" => SplitDebuginfo::Unpacked,
             "packed" => SplitDebuginfo::Packed,
-            _ => return Err(()),
+            _ => {
+                return Err(format!(
+                    "'{s}' is not a valid value for \
+                        split-debuginfo. Use 'off', 'unpacked', or 'packed'.",
+                ));
+            }
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(SplitDebuginfo);
+
 impl ToJson for SplitDebuginfo {
     fn to_json(&self) -> Json {
         self.as_str().to_json()
@@ -1378,7 +1518,9 @@ impl fmt::Display for SplitDebuginfo {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, serde_derive::Deserialize)]
+#[serde(tag = "kind")]
+#[serde(rename_all = "kebab-case")]
 pub enum StackProbeType {
     /// Don't emit any stack probes.
     None,
@@ -1390,44 +1532,10 @@ pub enum StackProbeType {
     Call,
     /// Use inline option for LLVM versions later than specified in `min_llvm_version_for_inline`
     /// and call `__rust_probestack` otherwise.
-    InlineOrCall { min_llvm_version_for_inline: (u32, u32, u32) },
-}
-
-impl StackProbeType {
-    fn from_json(json: &Json) -> Result<Self, String> {
-        let object = json.as_object().ok_or_else(|| "expected a JSON object")?;
-        let kind = object
-            .get("kind")
-            .and_then(|o| o.as_str())
-            .ok_or_else(|| "expected `kind` to be a string")?;
-        match kind {
-            "none" => Ok(StackProbeType::None),
-            "inline" => Ok(StackProbeType::Inline),
-            "call" => Ok(StackProbeType::Call),
-            "inline-or-call" => {
-                let min_version = object
-                    .get("min-llvm-version-for-inline")
-                    .and_then(|o| o.as_array())
-                    .ok_or_else(|| "expected `min-llvm-version-for-inline` to be an array")?;
-                let mut iter = min_version.into_iter().map(|v| {
-                    let int = v.as_u64().ok_or_else(
-                        || "expected `min-llvm-version-for-inline` values to be integers",
-                    )?;
-                    u32::try_from(int)
-                        .map_err(|_| "`min-llvm-version-for-inline` values don't convert to u32")
-                });
-                let min_llvm_version_for_inline = (
-                    iter.next().unwrap_or(Ok(11))?,
-                    iter.next().unwrap_or(Ok(0))?,
-                    iter.next().unwrap_or(Ok(0))?,
-                );
-                Ok(StackProbeType::InlineOrCall { min_llvm_version_for_inline })
-            }
-            _ => Err(String::from(
-                "`kind` expected to be one of `none`, `inline`, `call` or `inline-or-call`",
-            )),
-        }
-    }
+    InlineOrCall {
+        #[serde(rename = "min-llvm-version-for-inline")]
+        min_llvm_version_for_inline: (u32, u32, u32),
+    },
 }
 
 impl ToJson for StackProbeType {
@@ -1549,6 +1657,29 @@ impl fmt::Display for SanitizerSet {
     }
 }
 
+impl FromStr for SanitizerSet {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(match s {
+            "address" => SanitizerSet::ADDRESS,
+            "cfi" => SanitizerSet::CFI,
+            "dataflow" => SanitizerSet::DATAFLOW,
+            "kcfi" => SanitizerSet::KCFI,
+            "kernel-address" => SanitizerSet::KERNELADDRESS,
+            "leak" => SanitizerSet::LEAK,
+            "memory" => SanitizerSet::MEMORY,
+            "memtag" => SanitizerSet::MEMTAG,
+            "safestack" => SanitizerSet::SAFESTACK,
+            "shadow-call-stack" => SanitizerSet::SHADOWCALLSTACK,
+            "thread" => SanitizerSet::THREAD,
+            "hwaddress" => SanitizerSet::HWADDRESS,
+            s => return Err(format!("unknown sanitizer {s}")),
+        })
+    }
+}
+
+crate::json::serde_deserialize_from_str!(SanitizerSet);
+
 impl ToJson for SanitizerSet {
     fn to_json(&self) -> Json {
         self.into_iter()
@@ -1587,17 +1718,19 @@ impl FramePointer {
 }
 
 impl FromStr for FramePointer {
-    type Err = ();
-    fn from_str(s: &str) -> Result<Self, ()> {
+    type Err = String;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
         Ok(match s {
             "always" => Self::Always,
             "non-leaf" => Self::NonLeaf,
             "may-omit" => Self::MayOmit,
-            _ => return Err(()),
+            _ => return Err(format!("'{s}' is not a valid value for frame-pointer")),
         })
     }
 }
 
+crate::json::serde_deserialize_from_str!(FramePointer);
+
 impl ToJson for FramePointer {
     fn to_json(&self) -> Json {
         match *self {
@@ -1685,7 +1818,7 @@ impl BinaryFormat {
 }
 
 impl FromStr for BinaryFormat {
-    type Err = ();
+    type Err = String;
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s {
             "coff" => Ok(Self::Coff),
@@ -1693,11 +1826,16 @@ impl FromStr for BinaryFormat {
             "mach-o" => Ok(Self::MachO),
             "wasm" => Ok(Self::Wasm),
             "xcoff" => Ok(Self::Xcoff),
-            _ => Err(()),
+            _ => Err(format!(
+                "'{s}' is not a valid value for binary_format. \
+                    Use 'coff', 'elf', 'mach-o', 'wasm' or 'xcoff' "
+            )),
         }
     }
 }
 
+crate::json::serde_deserialize_from_str!(BinaryFormat);
+
 impl ToJson for BinaryFormat {
     fn to_json(&self) -> Json {
         match self {
@@ -2130,12 +2268,11 @@ pub(crate) use cvs;
 #[derive(Debug, PartialEq)]
 pub struct TargetWarnings {
     unused_fields: Vec<String>,
-    incorrect_type: Vec<String>,
 }
 
 impl TargetWarnings {
     pub fn empty() -> Self {
-        Self { unused_fields: Vec::new(), incorrect_type: Vec::new() }
+        Self { unused_fields: Vec::new() }
     }
 
     pub fn warning_messages(&self) -> Vec<String> {
@@ -2146,12 +2283,6 @@ impl TargetWarnings {
                 self.unused_fields.join(", ")
             ));
         }
-        if !self.incorrect_type.is_empty() {
-            warnings.push(format!(
-                "target json file contains fields whose value doesn't have the correct json type: {}",
-                self.incorrect_type.join(", ")
-            ));
-        }
         warnings
     }
 }
@@ -3325,7 +3456,8 @@ impl Target {
     /// Test target self-consistency and JSON encoding/decoding roundtrip.
     #[cfg(test)]
     fn test_target(mut self) {
-        let recycled_target = Target::from_json(self.to_json()).map(|(j, _)| j);
+        let recycled_target =
+            Target::from_json(&serde_json::to_string(&self.to_json()).unwrap()).map(|(j, _)| j);
         self.update_to_cli();
         self.check_consistency(TargetKind::Builtin).unwrap();
         assert_eq!(recycled_target, Ok(self));
@@ -3373,8 +3505,7 @@ impl Target {
 
         fn load_file(path: &Path) -> Result<(Target, TargetWarnings), String> {
             let contents = fs::read_to_string(path).map_err(|e| e.to_string())?;
-            let obj = serde_json::from_str(&contents).map_err(|e| e.to_string())?;
-            Target::from_json(obj)
+            Target::from_json(&contents)
         }
 
         match *target_tuple {
@@ -3422,10 +3553,7 @@ impl Target {
                     Err(format!("could not find specification for target {target_tuple:?}"))
                 }
             }
-            TargetTuple::TargetJson { ref contents, .. } => {
-                let obj = serde_json::from_str(contents).map_err(|e| e.to_string())?;
-                Target::from_json(obj)
-            }
+            TargetTuple::TargetJson { ref contents, .. } => Target::from_json(contents),
         }
     }
 
diff --git a/compiler/rustc_target/src/tests.rs b/compiler/rustc_target/src/tests.rs
index 76375170db63d..ee847a84007f0 100644
--- a/compiler/rustc_target/src/tests.rs
+++ b/compiler/rustc_target/src/tests.rs
@@ -2,8 +2,7 @@ use crate::spec::Target;
 
 #[test]
 fn report_unused_fields() {
-    let json = serde_json::from_str(
-        r#"
+    let json = r#"
     {
         "arch": "powerpc64",
         "data-layout": "e-m:e-i64:64-n32:64",
@@ -11,47 +10,8 @@ fn report_unused_fields() {
         "target-pointer-width": "64",
         "code-mode": "foo"
     }
-    "#,
-    )
-    .unwrap();
-    let warnings = Target::from_json(json).unwrap().1;
-    assert_eq!(warnings.warning_messages().len(), 1);
-    assert!(warnings.warning_messages().join("\n").contains("code-mode"));
-}
-
-#[test]
-fn report_incorrect_json_type() {
-    let json = serde_json::from_str(
-        r#"
-    {
-        "arch": "powerpc64",
-        "data-layout": "e-m:e-i64:64-n32:64",
-        "llvm-target": "powerpc64le-elf",
-        "target-pointer-width": "64",
-        "link-env-remove": "foo"
-    }
-    "#,
-    )
-    .unwrap();
-    let warnings = Target::from_json(json).unwrap().1;
-    assert_eq!(warnings.warning_messages().len(), 1);
-    assert!(warnings.warning_messages().join("\n").contains("link-env-remove"));
-}
-
-#[test]
-fn no_warnings_for_valid_target() {
-    let json = serde_json::from_str(
-        r#"
-    {
-        "arch": "powerpc64",
-        "data-layout": "e-m:e-i64:64-n32:64",
-        "llvm-target": "powerpc64le-elf",
-        "target-pointer-width": "64",
-        "link-env-remove": ["foo"]
-    }
-    "#,
-    )
-    .unwrap();
-    let warnings = Target::from_json(json).unwrap().1;
-    assert_eq!(warnings.warning_messages().len(), 0);
+    "#;
+    let result = Target::from_json(json);
+    eprintln!("{result:#?}");
+    assert!(result.is_err());
 }
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index 38ba6b4503dc1..a32c2f7fb18c5 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -444,7 +444,7 @@ fn add_exe_suffix(input: String, target: &TargetTuple) -> String {
     let exe_suffix = match target {
         TargetTuple::TargetTuple(_) => Target::expect_builtin(target).options.exe_suffix,
         TargetTuple::TargetJson { contents, .. } => {
-            Target::from_json(contents.parse().unwrap()).unwrap().0.options.exe_suffix
+            Target::from_json(contents).unwrap().0.options.exe_suffix
         }
     };
     input + &exe_suffix
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index f43f5eae9a560..d17ae162ab235 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -378,6 +378,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "serde",
     "serde_derive",
     "serde_json",
+    "serde_path_to_error",
     "sha1",
     "sha2",
     "sharded-slab",
diff --git a/tests/run-make/rustdoc-target-spec-json-path/target.json b/tests/run-make/rustdoc-target-spec-json-path/target.json
index c478f1196fae0..d7e4cac57ae75 100644
--- a/tests/run-make/rustdoc-target-spec-json-path/target.json
+++ b/tests/run-make/rustdoc-target-spec-json-path/target.json
@@ -6,7 +6,6 @@
   "dynamic-linking": true,
   "env": "gnu",
   "executables": true,
-  "has-elf-tls": true,
   "has-rpath": true,
   "linker-is-gnu": true,
   "llvm-target": "x86_64-unknown-linux-gnu",
diff --git a/tests/run-make/target-specs/endianness-mismatch.json b/tests/run-make/target-specs/endianness-mismatch.json
index 431053ea99b60..cc03becc59af6 100644
--- a/tests/run-make/target-specs/endianness-mismatch.json
+++ b/tests/run-make/target-specs/endianness-mismatch.json
@@ -5,7 +5,6 @@
     "llvm-target": "x86_64-unknown-linux-gnu",
     "target-endian": "big",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
     "arch": "x86_64",
     "os": "linux"
 }
diff --git a/tests/run-make/target-specs/my-awesome-platform.json b/tests/run-make/target-specs/my-awesome-platform.json
index 1673ef7bd54d1..d41038b84a865 100644
--- a/tests/run-make/target-specs/my-awesome-platform.json
+++ b/tests/run-make/target-specs/my-awesome-platform.json
@@ -4,8 +4,6 @@
     "llvm-target": "i686-unknown-linux-gnu",
     "target-endian": "little",
     "target-pointer-width": "32",
-    "target-c-int-width": "32",
     "arch": "x86",
-    "os": "linux",
-    "morestack": false
+    "os": "linux"
 }
diff --git a/tests/run-make/target-specs/my-incomplete-platform.json b/tests/run-make/target-specs/my-incomplete-platform.json
index ceaa25cdf2fef..8bdc4108f494a 100644
--- a/tests/run-make/target-specs/my-incomplete-platform.json
+++ b/tests/run-make/target-specs/my-incomplete-platform.json
@@ -3,8 +3,6 @@
     "linker-flavor": "gcc",
     "target-endian": "little",
     "target-pointer-width": "32",
-    "target-c-int-width": "32",
     "arch": "x86",
-    "os": "foo",
-    "morestack": false
+    "os": "foo"
 }
diff --git a/tests/run-make/target-specs/my-x86_64-unknown-linux-gnu-platform.json b/tests/run-make/target-specs/my-x86_64-unknown-linux-gnu-platform.json
index 0cafce15a9fef..27833f1abdd9e 100644
--- a/tests/run-make/target-specs/my-x86_64-unknown-linux-gnu-platform.json
+++ b/tests/run-make/target-specs/my-x86_64-unknown-linux-gnu-platform.json
@@ -5,8 +5,6 @@
     "llvm-target": "x86_64-unknown-linux-gnu",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
     "arch": "x86_64",
-    "os": "linux",
-    "morestack": false
+    "os": "linux"
 }
diff --git a/tests/run-make/target-specs/require-explicit-cpu.json b/tests/run-make/target-specs/require-explicit-cpu.json
index 5cbb9573b3f12..9744bca168e2d 100644
--- a/tests/run-make/target-specs/require-explicit-cpu.json
+++ b/tests/run-make/target-specs/require-explicit-cpu.json
@@ -4,7 +4,6 @@
     "llvm-target": "i686-unknown-linux-gnu",
     "target-endian": "little",
     "target-pointer-width": "32",
-    "target-c-int-width": "32",
     "arch": "x86",
     "os": "linux",
     "need-explicit-cpu": true
diff --git a/tests/run-make/target-specs/rmake.rs b/tests/run-make/target-specs/rmake.rs
index 9184e5f772f78..7e565588ed6bc 100644
--- a/tests/run-make/target-specs/rmake.rs
+++ b/tests/run-make/target-specs/rmake.rs
@@ -8,8 +8,6 @@
 use run_make_support::{diff, rfs, rustc};
 
 fn main() {
-    rustc().input("foo.rs").target("my-awesome-platform.json").crate_type("lib").emit("asm").run();
-    assert!(!rfs::read_to_string("foo.s").contains("morestack"));
     rustc()
         .input("foo.rs")
         .target("my-invalid-platform.json")
@@ -19,7 +17,7 @@ fn main() {
         .input("foo.rs")
         .target("my-incomplete-platform.json")
         .run_fail()
-        .assert_stderr_contains("Field llvm-target");
+        .assert_stderr_contains("missing field `llvm-target`");
     rustc()
         .env("RUST_TARGET_PATH", ".")
         .input("foo.rs")
diff --git a/tests/ui/check-cfg/my-awesome-platform.json b/tests/ui/check-cfg/my-awesome-platform.json
index 03b08b727bd3a..4c16d06c7b7d6 100644
--- a/tests/ui/check-cfg/my-awesome-platform.json
+++ b/tests/ui/check-cfg/my-awesome-platform.json
@@ -4,7 +4,6 @@
     "arch": "x86_64",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
     "os": "ericos",
     "linker-flavor": "ld.lld",
     "linker": "rust-lld",
diff --git a/tests/ui/codegen/mismatched-data-layout.json b/tests/ui/codegen/mismatched-data-layout.json
index 7adc883252474..f8c510c186362 100644
--- a/tests/ui/codegen/mismatched-data-layout.json
+++ b/tests/ui/codegen/mismatched-data-layout.json
@@ -4,7 +4,6 @@
     "arch": "x86_64",
     "target-endian": "little",
     "target-pointer-width": "64",
-    "target-c-int-width": "32",
     "os": "none",
     "linker-flavor": "ld.lld",
     "linker": "rust-lld",
diff --git a/tests/ui/codegen/mismatched-data-layouts.rs b/tests/ui/codegen/mismatched-data-layouts.rs
index 6428b8c5247b7..ea1457148a52c 100644
--- a/tests/ui/codegen/mismatched-data-layouts.rs
+++ b/tests/ui/codegen/mismatched-data-layouts.rs
@@ -5,6 +5,7 @@
 //@ compile-flags: --crate-type=lib --target={{src-base}}/codegen/mismatched-data-layout.json -Z unstable-options
 //@ normalize-stderr: "`, `[A-Za-z0-9-:]*`" -> "`, `normalized data layout`"
 //@ normalize-stderr: "layout, `[A-Za-z0-9-:]*`" -> "layout, `normalized data layout`"
+//@ normalize-stderr: "`mismatched-data-layout-\d+`" -> "`mismatched-data-layout-<hash>`"
 
 #![feature(lang_items, no_core, auto_traits)]
 #![no_core]
diff --git a/tests/ui/codegen/mismatched-data-layouts.stderr b/tests/ui/codegen/mismatched-data-layouts.stderr
index b7d5d82bee08c..d1117564d5b73 100644
--- a/tests/ui/codegen/mismatched-data-layouts.stderr
+++ b/tests/ui/codegen/mismatched-data-layouts.stderr
@@ -1,4 +1,4 @@
-error: data-layout for target `mismatched-data-layout-7193370089426056427`, `normalized data layout`, differs from LLVM target's `x86_64-unknown-none-gnu` default layout, `normalized data layout`
+error: data-layout for target `mismatched-data-layout-<hash>`, `normalized data layout`, differs from LLVM target's `x86_64-unknown-none-gnu` default layout, `normalized data layout`
 
 error: aborting due to 1 previous error