Auto merge of #112465 - GuillaumeGomez:rollup-gyh5buc, r=GuillaumeGomez

Rollup of 3 pull requests

Successful merges:

 - #112260 (Improve document of `unsafe_code` lint)
 - #112429 ([rustdoc] List matching impls on type aliases)
 - #112442 (Deduplicate identical region constraints in new solver)

r? `@ghost`
`@rustbot` modify labels: rollup

2 files changed, 23 insertions, 5 deletions

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 8c0956a618d..ff2989112af 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -286,7 +286,9 @@ impl<'tcx> LateLintPass<'tcx> for NonShorthandFieldPatterns {
 }
 
 declare_lint! {
-    /// The `unsafe_code` lint catches usage of `unsafe` code.
+    /// The `unsafe_code` lint catches usage of `unsafe` code and other
+    /// potentially unsound constructs like `no_mangle`, `export_name`,
+    /// and `link_section`.
     ///
     /// ### Example
     ///
@@ -297,17 +299,29 @@ declare_lint! {
     ///
     ///     }
     /// }
+    ///
+    /// #[no_mangle]
+    /// fn func_0() { }
+    ///
+    /// #[export_name = "exported_symbol_name"]
+    /// pub fn name_in_rust() { }
+    ///
+    /// #[no_mangle]
+    /// #[link_section = ".example_section"]
+    /// pub static VAR1: u32 = 1;
     /// ```
     ///
     /// {{produces}}
     ///
     /// ### Explanation
     ///
-    /// This lint is intended to restrict the usage of `unsafe`, which can be
-    /// difficult to use correctly.
+    /// This lint is intended to restrict the usage of `unsafe` blocks and other
+    /// constructs (including, but not limited to `no_mangle`, `link_section`
+    /// and `export_name` attributes) wrong usage of which causes undefined
+    /// behavior.
     UNSAFE_CODE,
     Allow,
-    "usage of `unsafe` code"
+    "usage of `unsafe` code and other potentially unsound constructs"
 }
 
 declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
diff --git a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
index bca2343e424..72b3c3d0180 100644
--- a/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
+++ b/compiler/rustc_trait_selection/src/solve/eval_ctxt/canonical.rs
@@ -11,6 +11,7 @@
 use super::{CanonicalInput, Certainty, EvalCtxt, Goal};
 use crate::solve::canonicalize::{CanonicalizeMode, Canonicalizer};
 use crate::solve::{CanonicalResponse, QueryResult, Response};
+use rustc_data_structures::fx::FxHashSet;
 use rustc_index::IndexVec;
 use rustc_infer::infer::canonical::query_response::make_query_region_constraints;
 use rustc_infer::infer::canonical::CanonicalVarValues;
@@ -147,7 +148,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
         // Cannot use `take_registered_region_obligations` as we may compute the response
         // inside of a `probe` whenever we have multiple choices inside of the solver.
         let region_obligations = self.infcx.inner.borrow().region_obligations().to_owned();
-        let region_constraints = self.infcx.with_region_constraints(|region_constraints| {
+        let mut region_constraints = self.infcx.with_region_constraints(|region_constraints| {
             make_query_region_constraints(
                 self.tcx(),
                 region_obligations
@@ -157,6 +158,9 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
             )
         });
 
+        let mut seen = FxHashSet::default();
+        region_constraints.outlives.retain(|outlives| seen.insert(*outlives));
+
         let mut opaque_types = self.infcx.clone_opaque_types_for_query_response();
         // Only return opaque type keys for newly-defined opaques
         opaque_types.retain(|(a, _)| {