diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs index a82a0d3ce5232..dd63b4f20fa55 100644 --- a/src/librustc_typeck/check/coercion.rs +++ b/src/librustc_typeck/check/coercion.rs @@ -1216,7 +1216,7 @@ impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E> "supposed to be part of a block tail expression, but the \ expression is empty"); }); - fcx.suggest_mismatched_types_on_tail( + let pointing_at_return_type = fcx.suggest_mismatched_types_on_tail( &mut db, expr, expected, @@ -1224,20 +1224,52 @@ impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E> cause.span, blk_id, ); - if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() { - if !sp.overlaps(cause.span) { + // FIXME: replace with navigating up the chain until hitting an fn or + // bailing if no "pass-through" Node is found, in order to provide a + // suggestion when encountering something like: + // ``` + // fn foo(a: bool) -> impl Debug { + // if a { + // bar()?; + // } + // { + // let x = unsafe { bar() }; + // x + // } + // } + // ``` + // + // Verify that this is a tail expression of a function, otherwise the + // label pointing out the cause for the type coercion will be wrong + // as prior return coercions would not be relevant (#57664). + let parent_id = fcx.tcx.hir().get_parent_node(blk_id); + let parent = fcx.tcx.hir().get(fcx.tcx.hir().get_parent_node(parent_id)); + if fcx.get_node_fn_decl(parent).is_some() && !pointing_at_return_type { + if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() { db.span_label(*sp, reason_label); } } } - _ => { + ObligationCauseCode::ReturnType(_id) => { db = fcx.report_mismatched_types(cause, expected, found, err); - if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() { + let _id = fcx.tcx.hir().get_parent_node(_id); + let mut pointing_at_return_type = false; + if let Some((fn_decl, can_suggest)) = fcx.get_fn_decl(_id) { + pointing_at_return_type = fcx.suggest_missing_return_type( + &mut db, &fn_decl, expected, found, can_suggest); + } + if let (Some(sp), false) = ( + fcx.ret_coercion_span.borrow().as_ref(), + pointing_at_return_type, + ) { if !sp.overlaps(cause.span) { db.span_label(*sp, reason_label); } } } + _ => { + db = fcx.report_mismatched_types(cause, expected, found, err); + } } if let Some(augment_error) = augment_error { diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs index 1b07385d4d1f4..7b9b97ff065a6 100644 --- a/src/librustc_typeck/check/mod.rs +++ b/src/librustc_typeck/check/mod.rs @@ -4347,11 +4347,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { struct_span_err!(self.tcx.sess, expr.span, E0572, "return statement outside of function body").emit(); } else if let Some(ref e) = *expr_opt { - *self.ret_coercion_span.borrow_mut() = Some(e.span); + if self.ret_coercion_span.borrow().is_none() { + *self.ret_coercion_span.borrow_mut() = Some(e.span); + } self.check_return_expr(e); } else { let mut coercion = self.ret_coercion.as_ref().unwrap().borrow_mut(); - *self.ret_coercion_span.borrow_mut() = Some(expr.span); + if self.ret_coercion_span.borrow().is_none() { + *self.ret_coercion_span.borrow_mut() = Some(expr.span); + } let cause = self.cause(expr.span, ObligationCauseCode::ReturnNoExpression); if let Some((fn_decl, _)) = self.get_fn_decl(expr.id) { coercion.coerce_forced_unit( @@ -5089,12 +5093,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { found: Ty<'tcx>, cause_span: Span, blk_id: ast::NodeId, - ) { + ) -> bool { self.suggest_missing_semicolon(err, expression, expected, cause_span); + let mut pointing_at_return_type = false; if let Some((fn_decl, can_suggest)) = self.get_fn_decl(blk_id) { - self.suggest_missing_return_type(err, &fn_decl, expected, found, can_suggest); + pointing_at_return_type = self.suggest_missing_return_type( + err, &fn_decl, expected, found, can_suggest); } self.suggest_ref_or_into(err, expression, expected, found); + pointing_at_return_type } pub fn suggest_ref_or_into( @@ -5193,12 +5200,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { /// This routine checks if the return type is left as default, the method is not part of an /// `impl` block and that it isn't the `main` method. If so, it suggests setting the return /// type. - fn suggest_missing_return_type(&self, - err: &mut DiagnosticBuilder<'tcx>, - fn_decl: &hir::FnDecl, - expected: Ty<'tcx>, - found: Ty<'tcx>, - can_suggest: bool) { + fn suggest_missing_return_type( + &self, + err: &mut DiagnosticBuilder<'tcx>, + fn_decl: &hir::FnDecl, + expected: Ty<'tcx>, + found: Ty<'tcx>, + can_suggest: bool, + ) -> bool { // Only suggest changing the return type for methods that // haven't set a return type at all (and aren't `fn main()` or an impl). match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) { @@ -5208,16 +5217,19 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { "try adding a return type", format!("-> {} ", self.resolve_type_vars_with_obligations(found)), Applicability::MachineApplicable); + true } (&hir::FunctionRetTy::DefaultReturn(span), false, true, true) => { err.span_label(span, "possibly return type missing here?"); + true } (&hir::FunctionRetTy::DefaultReturn(span), _, false, true) => { // `fn main()` must return `()`, do not suggest changing return type err.span_label(span, "expected `()` because of default return type"); + true } // expectation was caused by something else, not the default return - (&hir::FunctionRetTy::DefaultReturn(_), _, _, false) => {} + (&hir::FunctionRetTy::DefaultReturn(_), _, _, false) => false, (&hir::FunctionRetTy::Return(ref ty), _, _, _) => { // Only point to return type if the expected type is the return type, as if they // are not, the expectation must have been caused by something else. @@ -5229,7 +5241,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { if ty.sty == expected.sty { err.span_label(sp, format!("expected `{}` because of return type", expected)); + return true; } + false } } } diff --git a/src/test/ui/fully-qualified-type/fully-qualified-type-name2.stderr b/src/test/ui/fully-qualified-type/fully-qualified-type-name2.stderr index 9a33d29766fb9..47bb5e475b473 100644 --- a/src/test/ui/fully-qualified-type/fully-qualified-type-name2.stderr +++ b/src/test/ui/fully-qualified-type/fully-qualified-type-name2.stderr @@ -1,6 +1,8 @@ error[E0308]: mismatched types --> $DIR/fully-qualified-type-name2.rs:12:12 | +LL | fn bar(x: x::Foo) -> y::Foo { + | ------ expected `y::Foo` because of return type LL | return x; | ^ expected enum `y::Foo`, found enum `x::Foo` | diff --git a/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr b/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr index f03aaa67edbb8..b341879ab919a 100644 --- a/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr +++ b/src/test/ui/fully-qualified-type/fully-qualified-type-name4.stderr @@ -1,6 +1,8 @@ error[E0308]: mismatched types --> $DIR/fully-qualified-type-name4.rs:6:12 | +LL | fn bar(x: usize) -> Option { + | ------------- expected `std::option::Option` because of return type LL | return x; | ^ expected enum `std::option::Option`, found usize | diff --git a/src/test/ui/liveness/liveness-forgot-ret.stderr b/src/test/ui/liveness/liveness-forgot-ret.stderr index bbcbbdbe8dd5b..a970b80fdbbd9 100644 --- a/src/test/ui/liveness/liveness-forgot-ret.stderr +++ b/src/test/ui/liveness/liveness-forgot-ret.stderr @@ -2,7 +2,7 @@ error[E0308]: mismatched types --> $DIR/liveness-forgot-ret.rs:3:19 | LL | fn f(a: isize) -> isize { if god_exists(a) { return 5; }; } - | - ^^^^^ expected isize, found () - expected because of this statement + | - ^^^^^ expected isize, found () | | | this function's body doesn't return | diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.rs b/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.rs new file mode 100644 index 0000000000000..50f1fe873cb5f --- /dev/null +++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.rs @@ -0,0 +1,17 @@ +fn unrelated() -> Result<(), std::string::ParseError> { // #57664 + let x = 0; + + match x { + 1 => { + let property_value_as_string = "a".parse()?; + } + 2 => { + let value: &bool = unsafe { &42 }; + //~^ ERROR mismatched types + } + }; + + Ok(()) +} + +fn main() {} diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.stderr b/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.stderr new file mode 100644 index 0000000000000..edaa60e5b8d8b --- /dev/null +++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return-2.stderr @@ -0,0 +1,12 @@ +error[E0308]: mismatched types + --> $DIR/point-to-type-err-cause-on-impl-trait-return-2.rs:9:41 + | +LL | let value: &bool = unsafe { &42 }; + | ^^^ expected bool, found integer + | + = note: expected type `&bool` + found type `&{integer}` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0308`. diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs new file mode 100644 index 0000000000000..95b40368143ef --- /dev/null +++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.rs @@ -0,0 +1,36 @@ +fn foo() -> impl std::fmt::Display { + if false { + return 0i32; + } + 1u32 + //~^ ERROR mismatched types +} + +fn bar() -> impl std::fmt::Display { + if false { + return 0i32; + } else { + return 1u32; + //~^ ERROR mismatched types + } +} + +fn baz() -> impl std::fmt::Display { + if false { + //~^ ERROR mismatched types + return 0i32; + } else { + 1u32 + } +} + +fn qux() -> impl std::fmt::Display { + if false { + 0i32 + } else { + 1u32 + //~^ ERROR if and else have incompatible types + } +} + +fn main() {} diff --git a/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr new file mode 100644 index 0000000000000..62da0787b02a9 --- /dev/null +++ b/src/test/ui/point-to-type-err-cause-on-impl-trait-return.stderr @@ -0,0 +1,58 @@ +error[E0308]: mismatched types + --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:5:5 + | +LL | return 0i32; + | ---- expected because of this statement +LL | } +LL | 1u32 + | ^^^^ expected i32, found u32 + | + = note: expected type `i32` + found type `u32` + +error[E0308]: mismatched types + --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:13:16 + | +LL | return 0i32; + | ---- expected because of this statement +LL | } else { +LL | return 1u32; + | ^^^^ expected i32, found u32 + | + = note: expected type `i32` + found type `u32` + +error[E0308]: mismatched types + --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:19:5 + | +LL | / if false { +LL | | //~^ ERROR mismatched types +LL | | return 0i32; + | | ---- expected because of this statement +LL | | } else { +LL | | 1u32 +LL | | } + | |_____^ expected i32, found u32 + | + = note: expected type `i32` + found type `u32` + +error[E0308]: if and else have incompatible types + --> $DIR/point-to-type-err-cause-on-impl-trait-return.rs:31:9 + | +LL | / if false { +LL | | 0i32 + | | ---- expected because of this +LL | | } else { +LL | | 1u32 + | | ^^^^ expected i32, found u32 +LL | | //~^ ERROR if and else have incompatible types +LL | | } + | |_____- if and else have incompatible types + | + = note: expected type `i32` + found type `u32` + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0308`. diff --git a/src/test/ui/proc-macro/span-preservation.stderr b/src/test/ui/proc-macro/span-preservation.stderr index 1f9103a6d2ee8..db524907b656f 100644 --- a/src/test/ui/proc-macro/span-preservation.stderr +++ b/src/test/ui/proc-macro/span-preservation.stderr @@ -15,6 +15,9 @@ LL | let x: usize = "hello";;;;; //~ ERROR mismatched types error[E0308]: mismatched types --> $DIR/span-preservation.rs:19:29 | +LL | fn b(x: Option) -> usize { + | ----- expected `usize` because of return type +LL | match x { LL | Some(x) => { return x }, //~ ERROR mismatched types | ^ expected usize, found isize diff --git a/src/test/ui/return/return-from-diverging.stderr b/src/test/ui/return/return-from-diverging.stderr index c84dd1953a07b..2862ae641df15 100644 --- a/src/test/ui/return/return-from-diverging.stderr +++ b/src/test/ui/return/return-from-diverging.stderr @@ -1,6 +1,8 @@ error[E0308]: mismatched types --> $DIR/return-from-diverging.rs:4:12 | +LL | fn fail() -> ! { + | - expected `!` because of return type LL | return "wow"; //~ ERROR mismatched types | ^^^^^ expected !, found reference | diff --git a/src/test/ui/tail-typeck.stderr b/src/test/ui/tail-typeck.stderr index eadf3d6d3350e..1170f5c17c18a 100644 --- a/src/test/ui/tail-typeck.stderr +++ b/src/test/ui/tail-typeck.stderr @@ -2,7 +2,9 @@ error[E0308]: mismatched types --> $DIR/tail-typeck.rs:3:26 | LL | fn f() -> isize { return g(); } - | ^^^ expected isize, found usize + | ----- ^^^ expected isize, found usize + | | + | expected `isize` because of return type error: aborting due to previous error diff --git a/src/test/ui/wrong-ret-type.stderr b/src/test/ui/wrong-ret-type.stderr index 221806f731f60..cf59f42683d72 100644 --- a/src/test/ui/wrong-ret-type.stderr +++ b/src/test/ui/wrong-ret-type.stderr @@ -2,7 +2,9 @@ error[E0308]: mismatched types --> $DIR/wrong-ret-type.rs:2:49 | LL | fn mk_int() -> usize { let i: isize = 3; return i; } - | ^ expected usize, found isize + | ----- ^ expected usize, found isize + | | + | expected `usize` because of return type error: aborting due to previous error