diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs index 6c7d3a0c9c0bb..e8a0cc946b5e1 100644 --- a/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs +++ b/compiler/rustc_typeck/src/check/fn_ctxt/suggestions.rs @@ -9,7 +9,7 @@ use rustc_hir as hir; use rustc_hir::def::{CtorOf, DefKind}; use rustc_hir::lang_items::LangItem; use rustc_hir::{Expr, ExprKind, ItemKind, Node, Path, QPath, Stmt, StmtKind, TyKind}; -use rustc_infer::infer; +use rustc_infer::infer::{self, TyCtxtInferExt}; use rustc_middle::lint::in_external_macro; use rustc_middle::ty::{self, Binder, Ty}; use rustc_span::symbol::{kw, sym}; @@ -608,6 +608,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let bound_vars = self.tcx.late_bound_vars(fn_id); let ty = self.tcx.erase_late_bound_regions(Binder::bind_with_vars(ty, bound_vars)); let ty = self.normalize_associated_types_in(expr.span, ty); + let ty = match self.tcx.asyncness(fn_id.owner) { + hir::IsAsync::Async => self.tcx.infer_ctxt().enter(|infcx| { + infcx.get_impl_future_output_ty(ty).unwrap_or_else(|| { + span_bug!( + fn_decl.output.span(), + "failed to get output type of async function" + ) + }) + }), + hir::IsAsync::NotAsync => ty, + }; if self.can_coerce(found, ty) { err.multipart_suggestion( "you might have meant to return this value", diff --git a/src/test/ui/return/tail-expr-as-potential-return.rs b/src/test/ui/return/tail-expr-as-potential-return.rs index 83266abfa06e6..2c3610fb24d4e 100644 --- a/src/test/ui/return/tail-expr-as-potential-return.rs +++ b/src/test/ui/return/tail-expr-as-potential-return.rs @@ -1,3 +1,16 @@ +// > Suggest `return`ing tail expressions that match return type +// > +// > Some newcomers are confused by the behavior of tail expressions, +// > interpreting that "leaving out the `;` makes it the return value". +// > To help them go in the right direction, suggest using `return` instead +// > when applicable. +// (original commit description for this test) +// +// This test was amended to also serve as a regression test for #92308, where +// this suggestion would not trigger with async functions. +// +// edition:2018 + fn main() { let _ = foo(true); } @@ -5,6 +18,15 @@ fn main() { fn foo(x: bool) -> Result { if x { Err(42) //~ ERROR mismatched types + //| HELP you might have meant to return this value + } + Ok(42.0) +} + +async fn bar(x: bool) -> Result { + if x { + Err(42) //~ ERROR mismatched types + //| HELP you might have meant to return this value } Ok(42.0) } diff --git a/src/test/ui/return/tail-expr-as-potential-return.stderr b/src/test/ui/return/tail-expr-as-potential-return.stderr index 87ef18878d6f1..dec1cbc4624ef 100644 --- a/src/test/ui/return/tail-expr-as-potential-return.stderr +++ b/src/test/ui/return/tail-expr-as-potential-return.stderr @@ -1,9 +1,10 @@ error[E0308]: mismatched types - --> $DIR/tail-expr-as-potential-return.rs:7:9 + --> $DIR/tail-expr-as-potential-return.rs:28:9 | LL | / if x { LL | | Err(42) | | ^^^^^^^ expected `()`, found enum `Result` +LL | | //| HELP you might have meant to return this value LL | | } | |_____- expected this to be `()` | @@ -14,6 +15,23 @@ help: you might have meant to return this value LL | return Err(42); | ++++++ + -error: aborting due to previous error +error[E0308]: mismatched types + --> $DIR/tail-expr-as-potential-return.rs:20:9 + | +LL | / if x { +LL | | Err(42) + | | ^^^^^^^ expected `()`, found enum `Result` +LL | | //| HELP you might have meant to return this value +LL | | } + | |_____- expected this to be `()` + | + = note: expected unit type `()` + found enum `Result<_, {integer}>` +help: you might have meant to return this value + | +LL | return Err(42); + | ++++++ + + +error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0308`.