By tracking import use types to check whether it is scope uses or the other situations like module-relative uses, we can do more accurate redundant import checking.

fixes rust-lang#117448

For example unnecessary imports in std::prelude that can be eliminated:

```rust
use std::option::Option::Some;//~ WARNING the item `Some` is imported redundantly
use std::option::Option::None; //~ WARNING the item `None` is imported redundantly
```

Author: surechen

compiler/rustc_data_structures/src/owned_slice.rs

@@ -4,7 +4,7 @@ use crate::sync::Lrc;
 // Use our fake Send/Sync traits when on not parallel compiler,
 // so that `OwnedSlice` only implements/requires Send/Sync
 // for parallel compiler builds.
-use crate::sync::{Send, Sync};
+use crate::sync;
 
 /// An owned slice.
 ///
@@ -33,7 +33,7 @@ pub struct OwnedSlice {
     //       \/
     //      ⊂(´･◡･⊂ )∘˚˳° (I am the phantom remnant of #97770)
     #[expect(dead_code)]
-    owner: Lrc<dyn Send + Sync>,
+    owner: Lrc<dyn sync::Send + sync::Sync>,
 }
 
 /// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function.
@@ -60,7 +60,7 @@ pub struct OwnedSlice {
 /// ```
 pub fn slice_owned<O, F>(owner: O, slicer: F) -> OwnedSlice
 where
-    O: Send + Sync + 'static,
+    O: sync::Send + sync::Sync + 'static,
     F: FnOnce(&O) -> &[u8],
 {
     try_slice_owned(owner, |x| Ok::<_, !>(slicer(x))).into_ok()
@@ -71,7 +71,7 @@ where
 /// See [`slice_owned`] for the infallible version.
 pub fn try_slice_owned<O, F, E>(owner: O, slicer: F) -> Result<OwnedSlice, E>
 where
-    O: Send + Sync + 'static,
+    O: sync::Send + sync::Sync + 'static,
     F: FnOnce(&O) -> Result<&[u8], E>,
 {
     // We wrap the owner of the bytes in, so it doesn't move.
@@ -139,11 +139,11 @@ impl Borrow<[u8]> for OwnedSlice {
 
 // Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Send`
 #[cfg(parallel_compiler)]
-unsafe impl Send for OwnedSlice {}
+unsafe impl sync::Send for OwnedSlice {}
 
 // Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Sync`
 #[cfg(parallel_compiler)]
-unsafe impl Sync for OwnedSlice {}
+unsafe impl sync::Sync for OwnedSlice {}
 
 #[cfg(test)]
 mod tests;

compiler/rustc_hir_analysis/src/check/check.rs

@@ -5,10 +5,9 @@ use super::compare_impl_item::check_type_bounds;
 use super::compare_impl_item::{compare_impl_method, compare_impl_ty};
 use super::*;
 use rustc_attr as attr;
-use rustc_errors::{codes::*, ErrorGuaranteed, MultiSpan};
+use rustc_errors::{codes::*, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind};
-use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::Node;
 use rustc_infer::infer::{RegionVariableOrigin, TyCtxtInferExt};
 use rustc_infer::traits::{Obligation, TraitEngineExt as _};

compiler/rustc_hir_analysis/src/structured_errors/missing_cast_for_variadic_arg.rs

@@ -1,5 +1,5 @@
 use crate::{errors, structured_errors::StructuredDiagnostic};
-use rustc_errors::{codes::*, DiagnosticBuilder, ErrCode};
+use rustc_errors::{codes::*, DiagnosticBuilder};
 use rustc_middle::ty::{Ty, TypeVisitableExt};
 use rustc_session::Session;
 use rustc_span::Span;

compiler/rustc_hir_analysis/src/structured_errors/sized_unsized_cast.rs

@@ -1,5 +1,5 @@
 use crate::{errors, structured_errors::StructuredDiagnostic};
-use rustc_errors::{codes::*, DiagnosticBuilder, ErrCode};
+use rustc_errors::{codes::*, DiagnosticBuilder};
 use rustc_middle::ty::{Ty, TypeVisitableExt};
 use rustc_session::Session;
 use rustc_span::Span;

compiler/rustc_hir_analysis/src/structured_errors/wrong_number_of_generic_args.rs

@@ -1,7 +1,5 @@
 use crate::structured_errors::StructuredDiagnostic;
-use rustc_errors::{
-    codes::*, pluralize, Applicability, Diagnostic, DiagnosticBuilder, ErrCode, MultiSpan,
-};
+use rustc_errors::{codes::*, pluralize, Applicability, Diagnostic, DiagnosticBuilder, MultiSpan};
 use rustc_hir as hir;
 use rustc_middle::ty::{self as ty, AssocItems, AssocKind, TyCtxt};
 use rustc_session::Session;

compiler/rustc_hir_typeck/src/expr.rs

@@ -27,7 +27,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{
     codes::*, pluralize, struct_span_code_err, AddToDiagnostic, Applicability, Diagnostic,
-    DiagnosticBuilder, ErrCode, ErrorGuaranteed, StashKey,
+    DiagnosticBuilder, ErrorGuaranteed, StashKey,
 };
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind, Res};

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -13,7 +13,7 @@ use itertools::Itertools;
 use rustc_ast as ast;
 use rustc_data_structures::fx::FxIndexSet;
 use rustc_errors::{
-    codes::*, pluralize, Applicability, Diagnostic, ErrCode, ErrorGuaranteed, MultiSpan, StashKey,
+    codes::*, pluralize, Applicability, Diagnostic, ErrorGuaranteed, MultiSpan, StashKey,
 };
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};

compiler/rustc_hir_typeck/src/lib.rs

@@ -53,7 +53,7 @@ use crate::expectation::Expectation;
 use crate::fn_ctxt::LoweredTy;
 use crate::gather_locals::GatherLocalsVisitor;
 use rustc_data_structures::unord::UnordSet;
-use rustc_errors::{codes::*, struct_span_code_err, ErrCode, ErrorGuaranteed};
+use rustc_errors::{codes::*, struct_span_code_err, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::intravisit::Visitor;

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -5,7 +5,7 @@ use crate::errors::{
 use crate::infer::error_reporting::TypeErrCtxt;
 use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::InferCtxt;
-use rustc_errors::{codes::*, DiagnosticBuilder, ErrCode, IntoDiagnosticArg};
+use rustc_errors::{codes::*, DiagnosticBuilder, IntoDiagnosticArg};
 use rustc_hir as hir;
 use rustc_hir::def::Res;
 use rustc_hir::def::{CtorOf, DefKind, Namespace};

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -13,7 +13,7 @@ use rustc_data_structures::unhash::UnhashMap;
 use rustc_expand::base::{SyntaxExtension, SyntaxExtensionKind};
 use rustc_expand::proc_macro::{AttrProcMacro, BangProcMacro, DeriveProcMacro};
 use rustc_hir::def::Res;
-use rustc_hir::def_id::{DefIdMap, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_hir::def_id::{CRATE_DEF_INDEX, LOCAL_CRATE};
 use rustc_hir::definitions::{DefPath, DefPathData};
 use rustc_hir::diagnostic_items::DiagnosticItems;
 use rustc_index::Idx;