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Warn about const instability wrt MSRV #15297

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Merged
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Jul 18, 2025
Merged

Warn about const instability wrt MSRV #15297

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48 changes: 34 additions & 14 deletions clippy_lints/src/incompatible_msrv.rs
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
use clippy_config::Conf;
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::is_in_test;
use clippy_utils::msrvs::Msrv;
use rustc_attr_data_structures::{RustcVersion, Stability, StableSince};
use clippy_utils::{is_in_const_context, is_in_test};
use rustc_attr_data_structures::{RustcVersion, StabilityLevel, StableSince};
use rustc_data_structures::fx::FxHashMap;
use rustc_hir::def::DefKind;
use rustc_hir::{self as hir, AmbigArg, Expr, ExprKind, HirId, QPath};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty::TyCtxt;
Expand Down Expand Up @@ -80,7 +81,7 @@ enum Availability {

pub struct IncompatibleMsrv {
msrv: Msrv,
availability_cache: FxHashMap<DefId, Availability>,
availability_cache: FxHashMap<(DefId, bool), Availability>,
check_in_tests: bool,
}

Expand All @@ -96,29 +97,44 @@ impl IncompatibleMsrv {
}

/// Returns the availability of `def_id`, whether it is enabled through a feature or
/// available since a given version (the default being Rust 1.0.0).
fn get_def_id_availability(&mut self, tcx: TyCtxt<'_>, def_id: DefId) -> Availability {
if let Some(availability) = self.availability_cache.get(&def_id) {
/// available since a given version (the default being Rust 1.0.0). `needs_const` requires
/// the `const`-stability to be looked up instead of the stability in non-`const` contexts.
fn get_def_id_availability(&mut self, tcx: TyCtxt<'_>, def_id: DefId, needs_const: bool) -> Availability {
if let Some(availability) = self.availability_cache.get(&(def_id, needs_const)) {
return *availability;
}
let stability = tcx.lookup_stability(def_id);
let version = if stability.is_some_and(|stability| tcx.features().enabled(stability.feature)) {
let (feature, stability_level) = if needs_const {
tcx.lookup_const_stability(def_id)
.map(|stability| (stability.feature, stability.level))
.unzip()
} else {
tcx.lookup_stability(def_id)
.map(|stability| (stability.feature, stability.level))
.unzip()
};
let version = if feature.is_some_and(|feature| tcx.features().enabled(feature)) {
Availability::FeatureEnabled
} else if let Some(StableSince::Version(version)) = stability.as_ref().and_then(Stability::stable_since) {
} else if let Some(StableSince::Version(version)) =
stability_level.as_ref().and_then(StabilityLevel::stable_since)
{
Availability::Since(version)
} else if needs_const {
// Fallback to regular stability
self.get_def_id_availability(tcx, def_id, false)
} else if let Some(parent_def_id) = tcx.opt_parent(def_id) {
self.get_def_id_availability(tcx, parent_def_id)
self.get_def_id_availability(tcx, parent_def_id, needs_const)
} else {
Availability::Since(RustcVersion {
major: 1,
minor: 0,
patch: 0,
})
};
self.availability_cache.insert(def_id, version);
self.availability_cache.insert((def_id, needs_const), version);
version
}

/// Emit lint if `def_id`, associated with `node` and `span`, is below the current MSRV.
fn emit_lint_if_under_msrv(&mut self, cx: &LateContext<'_>, def_id: DefId, node: HirId, span: Span) {
if def_id.is_local() {
// We don't check local items since their MSRV is supposed to always be valid.
Expand All @@ -144,17 +160,22 @@ impl IncompatibleMsrv {
return;
}

let needs_const = cx.enclosing_body.is_some()
&& is_in_const_context(cx)
&& matches!(cx.tcx.def_kind(def_id), DefKind::AssocFn | DefKind::Fn);

if (self.check_in_tests || !is_in_test(cx.tcx, node))
&& let Some(current) = self.msrv.current(cx)
&& let Availability::Since(version) = self.get_def_id_availability(cx.tcx, def_id)
&& let Availability::Since(version) = self.get_def_id_availability(cx.tcx, def_id, needs_const)
&& version > current
{
span_lint_and_then(
cx,
INCOMPATIBLE_MSRV,
span,
format!(
"current MSRV (Minimum Supported Rust Version) is `{current}` but this item is stable since `{version}`"
"current MSRV (Minimum Supported Rust Version) is `{current}` but this item is stable{} since `{version}`",
if needs_const { " in a `const` context" } else { "" },
),
|diag| {
if is_under_cfg_attribute(cx, node) {
Expand All @@ -168,7 +189,6 @@ impl IncompatibleMsrv {

impl<'tcx> LateLintPass<'tcx> for IncompatibleMsrv {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
// TODO: check for const stability when in const context
match expr.kind {
ExprKind::MethodCall(_, _, _, span) => {
if let Some(method_did) = cx.typeck_results().type_dependent_def_id(expr.hir_id) {
Expand Down
40 changes: 40 additions & 0 deletions tests/ui/incompatible_msrv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
#![feature(strict_provenance)] // For use in test
#![clippy::msrv = "1.3.0"]

use std::cell::Cell;
use std::collections::HashMap;
use std::collections::hash_map::Entry;
use std::future::Future;
Expand Down Expand Up @@ -128,4 +129,43 @@ fn non_fn_items() {
//~^ incompatible_msrv
}

#[clippy::msrv = "1.87.0"]
fn msrv_non_ok_in_const() {
{
let c = Cell::new(42);
_ = c.get();
}
const {
let c = Cell::new(42);
_ = c.get();
//~^ incompatible_msrv
}
}

#[clippy::msrv = "1.88.0"]
fn msrv_ok_in_const() {
{
let c = Cell::new(42);
_ = c.get();
}
const {
let c = Cell::new(42);
_ = c.get();
}
}

#[clippy::msrv = "1.86.0"]
fn enum_variant_not_ok() {
let _ = std::io::ErrorKind::InvalidFilename;
//~^ incompatible_msrv
let _ = const { std::io::ErrorKind::InvalidFilename };
//~^ incompatible_msrv
}

#[clippy::msrv = "1.87.0"]
fn enum_variant_ok() {
let _ = std::io::ErrorKind::InvalidFilename;
let _ = const { std::io::ErrorKind::InvalidFilename };
}

fn main() {}
48 changes: 33 additions & 15 deletions tests/ui/incompatible_msrv.stderr
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.10.0`
--> tests/ui/incompatible_msrv.rs:15:39
--> tests/ui/incompatible_msrv.rs:16:39
|
LL | assert_eq!(map.entry("poneyland").key(), &"poneyland");
| ^^^^^
Expand All @@ -8,37 +8,37 @@ LL | assert_eq!(map.entry("poneyland").key(), &"poneyland");
= help: to override `-D warnings` add `#[allow(clippy::incompatible_msrv)]`

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.12.0`
--> tests/ui/incompatible_msrv.rs:21:11
--> tests/ui/incompatible_msrv.rs:22:11
|
LL | v.into_key();
| ^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.4.0`
--> tests/ui/incompatible_msrv.rs:25:5
--> tests/ui/incompatible_msrv.rs:26:5
|
LL | sleep(Duration::new(1, 0));
| ^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.2.0` but this item is stable since `1.3.0`
--> tests/ui/incompatible_msrv.rs:30:33
--> tests/ui/incompatible_msrv.rs:31:33
|
LL | static NO_BODY_BAD_MSRV: Option<Duration> = None;
| ^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.2.0` but this item is stable since `1.3.0`
--> tests/ui/incompatible_msrv.rs:37:19
--> tests/ui/incompatible_msrv.rs:38:19
|
LL | let _: Option<Duration> = None;
| ^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.43.0`
--> tests/ui/incompatible_msrv.rs:61:17
--> tests/ui/incompatible_msrv.rs:62:17
|
LL | let _ = core::iter::once_with(|| 0);
| ^^^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.43.0`
--> tests/ui/incompatible_msrv.rs:68:21
--> tests/ui/incompatible_msrv.rs:69:21
|
LL | let _ = core::iter::once_with(|| $msg);
| ^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -49,48 +49,66 @@ LL | my_panic!("foo");
= note: this error originates in the macro `my_panic` (in Nightly builds, run with -Z macro-backtrace for more info)

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.43.0`
--> tests/ui/incompatible_msrv.rs:75:13
--> tests/ui/incompatible_msrv.rs:76:13
|
LL | assert!(core::iter::once_with(|| 0).next().is_some());
| ^^^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.80.0` but this item is stable since `1.82.0`
--> tests/ui/incompatible_msrv.rs:88:13
--> tests/ui/incompatible_msrv.rs:89:13
|
LL | let _ = std::iter::repeat_n((), 5);
| ^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.82.0`
--> tests/ui/incompatible_msrv.rs:99:13
--> tests/ui/incompatible_msrv.rs:100:13
|
LL | let _ = std::iter::repeat_n((), 5);
| ^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.82.0`
--> tests/ui/incompatible_msrv.rs:104:17
--> tests/ui/incompatible_msrv.rs:105:17
|
LL | let _ = std::iter::repeat_n((), 5);
| ^^^^^^^^^^^^^^^^^^^
|
= note: you may want to conditionally increase the MSRV considered by Clippy using the `clippy::msrv` attribute

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.82.0`
--> tests/ui/incompatible_msrv.rs:109:17
--> tests/ui/incompatible_msrv.rs:110:17
|
LL | let _ = std::iter::repeat_n((), 5);
| ^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.78.0` but this item is stable since `1.84.0`
--> tests/ui/incompatible_msrv.rs:122:7
--> tests/ui/incompatible_msrv.rs:123:7
|
LL | r.isqrt()
| ^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.3.0` but this item is stable since `1.85.0`
--> tests/ui/incompatible_msrv.rs:127:13
--> tests/ui/incompatible_msrv.rs:128:13
|
LL | let _ = std::io::ErrorKind::CrossesDevices;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 14 previous errors
error: current MSRV (Minimum Supported Rust Version) is `1.87.0` but this item is stable in a `const` context since `1.88.0`
--> tests/ui/incompatible_msrv.rs:140:15
|
LL | _ = c.get();
| ^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.86.0` but this item is stable since `1.87.0`
--> tests/ui/incompatible_msrv.rs:159:13
|
LL | let _ = std::io::ErrorKind::InvalidFilename;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: current MSRV (Minimum Supported Rust Version) is `1.86.0` but this item is stable since `1.87.0`
--> tests/ui/incompatible_msrv.rs:161:21
|
LL | let _ = const { std::io::ErrorKind::InvalidFilename };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 17 previous errors