Auto merge of #127133 - matthiaskrgr:rollup-jxkp3yf, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - #123237 (Various rustc_codegen_ssa cleanups)
 - #126960 (Improve error message in tidy)
 - #127002 (Implement `x perf` as a separate tool)
 - #127081 (Add a run-make test that LLD is not being used by default on the x64 beta/stable channel)
 - #127106 (Improve unsafe extern blocks diagnostics)
 - #127110 (Fix a error suggestion for E0121 when using placeholder _ as return types on function signature.)
 - #127114 (fix: prefer `(*p).clone` to `p.clone` if the `p` is a raw pointer)
 - #127118 (Show `used attribute`'s kind for user when find it isn't applied to a `static` variable.)
 - #127122 (Remove uneccessary condition in `div_ceil`)

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

compiler/rustc_hir_analysis/src/collect.rs

@@ -1459,8 +1459,25 @@ fn infer_return_ty_for_fn_sig<'tcx>(
         Some(ty) => {
             let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
             // Typeck doesn't expect erased regions to be returned from `type_of`.
+            // This is a heuristic approach. If the scope has region paramters,
+            // we should change fn_sig's lifetime from `ReErased` to `ReError`,
+            // otherwise to `ReStatic`.
+            let has_region_params = generics.params.iter().any(|param| match param.kind {
+                GenericParamKind::Lifetime { .. } => true,
+                _ => false,
+            });
             let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r {
-                ty::ReErased => tcx.lifetimes.re_static,
+                ty::ReErased => {
+                    if has_region_params {
+                        ty::Region::new_error_with_message(
+                            tcx,
+                            DUMMY_SP,
+                            "erased region is not allowed here in return type",
+                        )
+                    } else {
+                        tcx.lifetimes.re_static
+                    }
+                }
                 _ => r,
             });