Rollup merge of #57723 - estebank:fix, r=davidtwco
Point at cause for expectation in return type type error
Various improvements and fixes for type errors in return expressions.
Fix #57664.
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index a82a0d3..dd63b4f 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -1216,7 +1216,7 @@
"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,
@@ -1224,7 +1224,44 @@
cause.span,
blk_id,
);
- if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() {
+ // 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);
+ 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);
}
@@ -1232,11 +1269,6 @@
}
_ => {
db = fcx.report_mismatched_types(cause, expected, found, err);
- if let Some(sp) = fcx.ret_coercion_span.borrow().as_ref() {
- if !sp.overlaps(cause.span) {
- db.span_label(*sp, reason_label);
- }
- }
}
}
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 4957a12..c9173df 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -4347,11 +4347,15 @@
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(
@@ -5081,12 +5085,15 @@
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(
@@ -5185,12 +5192,14 @@
/// 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()) {
@@ -5200,16 +5209,19 @@
"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.
@@ -5221,7 +5233,9 @@
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 9a33d29..47bb5e4 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 f03aaa6..b341879 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<usize> {
+ | ------------- expected `std::option::Option<usize>` 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 bbcbbdb..a970b80 100644
--- a/src/test/ui/liveness/liveness-forgot-ret.stderr
+++ b/src/test/ui/liveness/liveness-forgot-ret.stderr
@@ -2,7 +2,7 @@
--> $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 0000000..50f1fe8
--- /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 0000000..edaa60e
--- /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 0000000..95b4036
--- /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 0000000..62da078
--- /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 1f9103a..db52490 100644
--- a/src/test/ui/proc-macro/span-preservation.stderr
+++ b/src/test/ui/proc-macro/span-preservation.stderr
@@ -15,6 +15,9 @@
error[E0308]: mismatched types
--> $DIR/span-preservation.rs:19:29
|
+LL | fn b(x: Option<isize>) -> 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 c84dd19..2862ae6 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 eadf3d6..1170f5c 100644
--- a/src/test/ui/tail-typeck.stderr
+++ b/src/test/ui/tail-typeck.stderr
@@ -2,7 +2,9 @@
--> $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 221806f..cf59f42 100644
--- a/src/test/ui/wrong-ret-type.stderr
+++ b/src/test/ui/wrong-ret-type.stderr
@@ -2,7 +2,9 @@
--> $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
