diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index 18aff6a4d5a16..276aaec4141e6 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/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, }); diff --git a/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.fixed b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.fixed new file mode 100644 index 0000000000000..442ade6abf16d --- /dev/null +++ b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.fixed @@ -0,0 +1,33 @@ +//@ run-rustfix + +#[allow(dead_code)] + +fn main() { + struct S<'a>(&'a ()); + + fn f1(s: S<'_>) -> S<'_> { + //~^ ERROR the placeholder `_` is not allowed + s + } + + fn f2(s: S<'_>) -> S<'_> { + //~^ ERROR the placeholder `_` is not allowed + let x = true; + if x { + s + } else { + s + } + } + + fn f3(s: S<'_>) -> S<'_> { + //~^ ERROR the placeholder `_` is not allowed + return s; + } + + fn f4(s: S<'_>) -> S<'_> { + //~^ ERROR the placeholder `_` is not allowed + let _x = 1; + return s; + } +} diff --git a/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.rs b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.rs new file mode 100644 index 0000000000000..04ea3a28addfb --- /dev/null +++ b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.rs @@ -0,0 +1,33 @@ +//@ run-rustfix + +#[allow(dead_code)] + +fn main() { + struct S<'a>(&'a ()); + + fn f1(s: S<'_>) -> _ { + //~^ ERROR the placeholder `_` is not allowed + s + } + + fn f2(s: S<'_>) -> _ { + //~^ ERROR the placeholder `_` is not allowed + let x = true; + if x { + s + } else { + s + } + } + + fn f3(s: S<'_>) -> _ { + //~^ ERROR the placeholder `_` is not allowed + return s; + } + + fn f4(s: S<'_>) -> _ { + //~^ ERROR the placeholder `_` is not allowed + let _x = 1; + return s; + } +} diff --git a/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.stderr b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.stderr new file mode 100644 index 0000000000000..8b7c5e1681ad1 --- /dev/null +++ b/tests/ui/return/infer-return-ty-for-fn-sig-issue-125488.stderr @@ -0,0 +1,39 @@ +error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types + --> $DIR/infer-return-ty-for-fn-sig-issue-125488.rs:8:24 + | +LL | fn f1(s: S<'_>) -> _ { + | ^ + | | + | not allowed in type signatures + | help: replace with the correct return type: `S<'_>` + +error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types + --> $DIR/infer-return-ty-for-fn-sig-issue-125488.rs:13:24 + | +LL | fn f2(s: S<'_>) -> _ { + | ^ + | | + | not allowed in type signatures + | help: replace with the correct return type: `S<'_>` + +error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types + --> $DIR/infer-return-ty-for-fn-sig-issue-125488.rs:23:24 + | +LL | fn f3(s: S<'_>) -> _ { + | ^ + | | + | not allowed in type signatures + | help: replace with the correct return type: `S<'_>` + +error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types + --> $DIR/infer-return-ty-for-fn-sig-issue-125488.rs:28:24 + | +LL | fn f4(s: S<'_>) -> _ { + | ^ + | | + | not allowed in type signatures + | help: replace with the correct return type: `S<'_>` + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0121`. diff --git a/tests/ui/typeck/typeck_type_placeholder_item.rs b/tests/ui/typeck/typeck_type_placeholder_item.rs index a95b44e807c5d..29a21a1f45f56 100644 --- a/tests/ui/typeck/typeck_type_placeholder_item.rs +++ b/tests/ui/typeck/typeck_type_placeholder_item.rs @@ -47,7 +47,7 @@ impl Test9 { fn test11(x: &usize) -> &_ { //~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types - &x //~ ERROR cannot return reference to function parameter + &x } unsafe fn test12(x: *const usize) -> *const *const _ { diff --git a/tests/ui/typeck/typeck_type_placeholder_item.stderr b/tests/ui/typeck/typeck_type_placeholder_item.stderr index 7977504dae1d6..9d295f88da5aa 100644 --- a/tests/ui/typeck/typeck_type_placeholder_item.stderr +++ b/tests/ui/typeck/typeck_type_placeholder_item.stderr @@ -158,7 +158,7 @@ LL | fn test11(x: &usize) -> &_ { | -^ | || | |not allowed in type signatures - | help: replace with the correct return type: `&'static &'static usize` + | help: replace with the correct return type: `&&usize` error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types --> $DIR/typeck_type_placeholder_item.rs:53:52 @@ -687,13 +687,7 @@ help: add `#![feature(const_trait_impl)]` to the crate attributes to enable LL + #![feature(const_trait_impl)] | -error[E0515]: cannot return reference to function parameter `x` - --> $DIR/typeck_type_placeholder_item.rs:50:5 - | -LL | &x - | ^^ returns a reference to data owned by the current function - -error: aborting due to 75 previous errors +error: aborting due to 74 previous errors -Some errors have detailed explanations: E0015, E0046, E0121, E0282, E0403, E0515. +Some errors have detailed explanations: E0015, E0046, E0121, E0282, E0403. For more information about an error, try `rustc --explain E0015`.