diff --git a/compiler/rustc_hir_typeck/src/demand.rs b/compiler/rustc_hir_typeck/src/demand.rs
index 6c128d0aa1a65..665dc8b6a2f2a 100644
--- a/compiler/rustc_hir_typeck/src/demand.rs
+++ b/compiler/rustc_hir_typeck/src/demand.rs
@@ -85,6 +85,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
self.note_internal_mutation_in_method(err, expr, expected, expr_ty);
self.check_for_range_as_method_call(err, expr, expr_ty, expected);
self.check_for_binding_assigned_block_without_tail_expression(err, expr, expr_ty, expected);
+ self.check_wrong_return_type_due_to_generic_arg(err, expr, expr_ty);
}
/// Requires that the two types unify, and prints an error message if
@@ -1941,4 +1942,77 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
err.span_label(block.span, "this block is missing a tail expression");
}
}
+
+ fn check_wrong_return_type_due_to_generic_arg(
+ &self,
+ err: &mut Diagnostic,
+ expr: &hir::Expr<'_>,
+ checked_ty: Ty<'tcx>,
+ ) {
+ let Some(hir::Node::Expr(parent_expr)) = self.tcx.hir().find_parent(expr.hir_id) else { return; };
+ enum CallableKind {
+ Function,
+ Method,
+ Constructor,
+ }
+ let mut maybe_emit_help = |def_id: hir::def_id::DefId,
+ callable: rustc_span::symbol::Ident,
+ args: &[hir::Expr<'_>],
+ kind: CallableKind| {
+ let arg_idx = args.iter().position(|a| a.hir_id == expr.hir_id).unwrap();
+ let fn_ty = self.tcx.bound_type_of(def_id).0;
+ if !fn_ty.is_fn() {
+ return;
+ }
+ let fn_sig = fn_ty.fn_sig(self.tcx).skip_binder();
+ let Some(&arg) = fn_sig.inputs().get(arg_idx + if matches!(kind, CallableKind::Method) { 1 } else { 0 }) else { return; };
+ if matches!(arg.kind(), ty::Param(_))
+ && fn_sig.output().contains(arg)
+ && self.node_ty(args[arg_idx].hir_id) == checked_ty
+ {
+ let mut multi_span: MultiSpan = parent_expr.span.into();
+ multi_span.push_span_label(
+ args[arg_idx].span,
+ format!(
+ "this argument influences the {} of `{}`",
+ if matches!(kind, CallableKind::Constructor) {
+ "type"
+ } else {
+ "return type"
+ },
+ callable
+ ),
+ );
+ err.span_help(
+ multi_span,
+ format!(
+ "the {} `{}` due to the type of the argument passed",
+ match kind {
+ CallableKind::Function => "return type of this call is",
+ CallableKind::Method => "return type of this call is",
+ CallableKind::Constructor => "type constructed contains",
+ },
+ checked_ty
+ ),
+ );
+ }
+ };
+ match parent_expr.kind {
+ hir::ExprKind::Call(fun, args) => {
+ let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = fun.kind else { return; };
+ let hir::def::Res::Def(kind, def_id) = path.res else { return; };
+ let callable_kind = if matches!(kind, hir::def::DefKind::Ctor(_, _)) {
+ CallableKind::Constructor
+ } else {
+ CallableKind::Function
+ };
+ maybe_emit_help(def_id, path.segments[0].ident, args, callable_kind);
+ }
+ hir::ExprKind::MethodCall(method, _receiver, args, _span) => {
+ let Some(def_id) = self.typeck_results.borrow().type_dependent_def_id(parent_expr.hir_id) else { return; };
+ maybe_emit_help(def_id, method.ident, args, CallableKind::Method)
+ }
+ _ => return,
+ }
+ }
}
diff --git a/tests/ui/closures/issue-84128.stderr b/tests/ui/closures/issue-84128.stderr
index 59607afec8f8d..1cd8949b8c4b7 100644
--- a/tests/ui/closures/issue-84128.stderr
+++ b/tests/ui/closures/issue-84128.stderr
@@ -6,6 +6,13 @@ LL | Foo(())
| |
| arguments to this struct are incorrect
|
+help: the type constructed contains `()` due to the type of the argument passed
+ --> $DIR/issue-84128.rs:13:9
+ |
+LL | Foo(())
+ | ^^^^--^
+ | |
+ | this argument influences the type of `Foo`
note: tuple struct defined here
--> $DIR/issue-84128.rs:5:8
|
diff --git a/tests/ui/closures/issue-87461.stderr b/tests/ui/closures/issue-87461.stderr
index 72337892734e6..b492251c01691 100644
--- a/tests/ui/closures/issue-87461.stderr
+++ b/tests/ui/closures/issue-87461.stderr
@@ -6,6 +6,13 @@ LL | Ok(())
| |
| arguments to this enum variant are incorrect
|
+help: the type constructed contains `()` due to the type of the argument passed
+ --> $DIR/issue-87461.rs:10:5
+ |
+LL | Ok(())
+ | ^^^--^
+ | |
+ | this argument influences the type of `Ok`
note: tuple variant defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@@ -17,6 +24,13 @@ LL | Ok(())
| |
| arguments to this enum variant are incorrect
|
+help: the type constructed contains `()` due to the type of the argument passed
+ --> $DIR/issue-87461.rs:17:5
+ |
+LL | Ok(())
+ | ^^^--^
+ | |
+ | this argument influences the type of `Ok`
note: tuple variant defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
@@ -28,6 +42,13 @@ LL | Ok(())
| |
| arguments to this enum variant are incorrect
|
+help: the type constructed contains `()` due to the type of the argument passed
+ --> $DIR/issue-87461.rs:26:9
+ |
+LL | Ok(())
+ | ^^^--^
+ | |
+ | this argument influences the type of `Ok`
note: tuple variant defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
diff --git a/tests/ui/generic-associated-types/missing-bounds.stderr b/tests/ui/generic-associated-types/missing-bounds.stderr
index c913483a8747c..9f669b9a5214b 100644
--- a/tests/ui/generic-associated-types/missing-bounds.stderr
+++ b/tests/ui/generic-associated-types/missing-bounds.stderr
@@ -23,6 +23,13 @@ LL | A(self.0 + rhs.0)
|
= note: expected type parameter `B`
found associated type `::Output`
+help: the type constructed contains `::Output` due to the type of the argument passed
+ --> $DIR/missing-bounds.rs:11:9
+ |
+LL | A(self.0 + rhs.0)
+ | ^^--------------^
+ | |
+ | this argument influences the type of `A`
note: tuple struct defined here
--> $DIR/missing-bounds.rs:5:8
|
diff --git a/tests/ui/mismatched_types/issue-35030.stderr b/tests/ui/mismatched_types/issue-35030.stderr
index 680aff1726f9f..de4e067fead4c 100644
--- a/tests/ui/mismatched_types/issue-35030.stderr
+++ b/tests/ui/mismatched_types/issue-35030.stderr
@@ -11,6 +11,13 @@ LL | Some(true)
|
= note: expected type parameter `bool` (type parameter `bool`)
found type `bool` (`bool`)
+help: the type constructed contains `bool` due to the type of the argument passed
+ --> $DIR/issue-35030.rs:9:9
+ |
+LL | Some(true)
+ | ^^^^^----^
+ | |
+ | this argument influences the type of `Some`
note: tuple variant defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
diff --git a/tests/ui/suggestions/args-instead-of-tuple-errors.stderr b/tests/ui/suggestions/args-instead-of-tuple-errors.stderr
index 44a39efdf2542..bc097bf6eb451 100644
--- a/tests/ui/suggestions/args-instead-of-tuple-errors.stderr
+++ b/tests/ui/suggestions/args-instead-of-tuple-errors.stderr
@@ -11,6 +11,13 @@ LL | let _: Option<(i32, bool)> = Some(1, 2);
| ^
= note: expected tuple `(i32, bool)`
found type `{integer}`
+help: the type constructed contains `{integer}` due to the type of the argument passed
+ --> $DIR/args-instead-of-tuple-errors.rs:6:34
+ |
+LL | let _: Option<(i32, bool)> = Some(1, 2);
+ | ^^^^^-^^^^
+ | |
+ | this argument influences the type of `Some`
note: tuple variant defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
help: remove the extra argument
@@ -64,6 +71,13 @@ LL | let _: Option<(i32,)> = Some(5_usize);
|
= note: expected tuple `(i32,)`
found type `usize`
+help: the type constructed contains `usize` due to the type of the argument passed
+ --> $DIR/args-instead-of-tuple-errors.rs:14:29
+ |
+LL | let _: Option<(i32,)> = Some(5_usize);
+ | ^^^^^-------^
+ | |
+ | this argument influences the type of `Some`
note: tuple variant defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
@@ -77,6 +91,13 @@ LL | let _: Option<(i32,)> = Some((5_usize));
|
= note: expected tuple `(i32,)`
found type `usize`
+help: the type constructed contains `usize` due to the type of the argument passed
+ --> $DIR/args-instead-of-tuple-errors.rs:17:29
+ |
+LL | let _: Option<(i32,)> = Some((5_usize));
+ | ^^^^^---------^
+ | |
+ | this argument influences the type of `Some`
note: tuple variant defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
diff --git a/tests/ui/suggestions/sugg-else-for-closure.stderr b/tests/ui/suggestions/sugg-else-for-closure.stderr
index 5f59d0f541c99..7f05832bcd728 100644
--- a/tests/ui/suggestions/sugg-else-for-closure.stderr
+++ b/tests/ui/suggestions/sugg-else-for-closure.stderr
@@ -8,6 +8,13 @@ LL | let _s = y.unwrap_or(|| x.split('.').nth(1).unwrap());
|
= note: expected reference `&str`
found closure `[closure@$DIR/sugg-else-for-closure.rs:6:26: 6:28]`
+help: the return type of this call is `[closure@$DIR/sugg-else-for-closure.rs:6:26: 6:28]` due to the type of the argument passed
+ --> $DIR/sugg-else-for-closure.rs:6:14
+ |
+LL | let _s = y.unwrap_or(|| x.split('.').nth(1).unwrap());
+ | ^^^^^^^^^^^^-------------------------------^
+ | |
+ | this argument influences the return type of `unwrap_or`
note: associated function defined here
--> $SRC_DIR/core/src/option.rs:LL:COL
help: try calling `unwrap_or_else` instead
diff --git a/tests/ui/traits/issue-52893.stderr b/tests/ui/traits/issue-52893.stderr
index 7924d3db06f36..a11867c03a689 100644
--- a/tests/ui/traits/issue-52893.stderr
+++ b/tests/ui/traits/issue-52893.stderr
@@ -11,6 +11,13 @@ LL | builder.push(output);
|
= note: expected type parameter `F`
found struct `Class`
+help: the return type of this call is `Class
` due to the type of the argument passed
+ --> $DIR/issue-52893.rs:53:9
+ |
+LL | builder.push(output);
+ | ^^^^^^^^^^^^^------^
+ | |
+ | this argument influences the return type of `push`
note: associated function defined here
--> $DIR/issue-52893.rs:11:8
|
diff --git a/tests/ui/type/wrong-call-return-type-due-to-generic-arg.rs b/tests/ui/type/wrong-call-return-type-due-to-generic-arg.rs
new file mode 100644
index 0000000000000..ba5b9f54246e2
--- /dev/null
+++ b/tests/ui/type/wrong-call-return-type-due-to-generic-arg.rs
@@ -0,0 +1,28 @@
+fn function(x: T, y: bool) -> T {
+ x
+}
+
+struct S {}
+impl S {
+ fn method(&self, x: T) -> T {
+ x
+ }
+}
+
+fn wrong_arg_type(x: u32) -> u32 {
+ x
+}
+
+fn main() {
+ // Should not trigger.
+ let x = wrong_arg_type(0u16); //~ ERROR mismatched types
+ let x: u16 = function(0, 0u8); //~ ERROR mismatched types
+
+ // Should trigger exactly once for the first argument.
+ let x: u16 = function(0u32, 0u8); //~ ERROR arguments to this function are incorrect
+
+ // Should trigger.
+ let x: u16 = function(0u32, true); //~ ERROR mismatched types
+ let x: u16 = (S {}).method(0u32); //~ ERROR mismatched types
+ function(0u32, 8u8) //~ ERROR arguments to this function are incorrect
+}
diff --git a/tests/ui/type/wrong-call-return-type-due-to-generic-arg.stderr b/tests/ui/type/wrong-call-return-type-due-to-generic-arg.stderr
new file mode 100644
index 0000000000000..4d012cb156bb5
--- /dev/null
+++ b/tests/ui/type/wrong-call-return-type-due-to-generic-arg.stderr
@@ -0,0 +1,131 @@
+error[E0308]: mismatched types
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:18:28
+ |
+LL | let x = wrong_arg_type(0u16);
+ | -------------- ^^^^ expected `u32`, found `u16`
+ | |
+ | arguments to this function are incorrect
+ |
+note: function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:12:4
+ |
+LL | fn wrong_arg_type(x: u32) -> u32 {
+ | ^^^^^^^^^^^^^^ ------
+help: change the type of the numeric literal from `u16` to `u32`
+ |
+LL | let x = wrong_arg_type(0u32);
+ | ~~~
+
+error[E0308]: mismatched types
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:19:30
+ |
+LL | let x: u16 = function(0, 0u8);
+ | -------- ^^^ expected `bool`, found `u8`
+ | |
+ | arguments to this function are incorrect
+ |
+note: function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:1:4
+ |
+LL | fn function(x: T, y: bool) -> T {
+ | ^^^^^^^^ -------
+
+error[E0308]: arguments to this function are incorrect
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:22:18
+ |
+LL | let x: u16 = function(0u32, 0u8);
+ | ^^^^^^^^ ---- --- expected `bool`, found `u8`
+ | |
+ | expected `u16`, found `u32`
+ |
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:22:18
+ |
+LL | let x: u16 = function(0u32, 0u8);
+ | ^^^^^^^^^----^^^^^^
+ | |
+ | this argument influences the return type of `function`
+note: function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:1:4
+ |
+LL | fn function(x: T, y: bool) -> T {
+ | ^^^^^^^^ ---- -------
+help: change the type of the numeric literal from `u32` to `u16`
+ |
+LL | let x: u16 = function(0u16, 0u8);
+ | ~~~
+
+error[E0308]: mismatched types
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:25:27
+ |
+LL | let x: u16 = function(0u32, true);
+ | -------- ^^^^ expected `u16`, found `u32`
+ | |
+ | arguments to this function are incorrect
+ |
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:25:18
+ |
+LL | let x: u16 = function(0u32, true);
+ | ^^^^^^^^^----^^^^^^^
+ | |
+ | this argument influences the return type of `function`
+note: function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:1:4
+ |
+LL | fn function(x: T, y: bool) -> T {
+ | ^^^^^^^^ ----
+help: change the type of the numeric literal from `u32` to `u16`
+ |
+LL | let x: u16 = function(0u16, true);
+ | ~~~
+
+error[E0308]: mismatched types
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:26:32
+ |
+LL | let x: u16 = (S {}).method(0u32);
+ | ------ ^^^^ expected `u16`, found `u32`
+ | |
+ | arguments to this method are incorrect
+ |
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:26:18
+ |
+LL | let x: u16 = (S {}).method(0u32);
+ | ^^^^^^^^^^^^^^----^
+ | |
+ | this argument influences the return type of `method`
+note: associated function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:7:8
+ |
+LL | fn method(&self, x: T) -> T {
+ | ^^^^^^ ----
+help: change the type of the numeric literal from `u32` to `u16`
+ |
+LL | let x: u16 = (S {}).method(0u16);
+ | ~~~
+
+error[E0308]: arguments to this function are incorrect
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:27:5
+ |
+LL | function(0u32, 8u8)
+ | ^^^^^^^^ ---- --- expected `bool`, found `u8`
+ | |
+ | expected `()`, found `u32`
+ |
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:27:5
+ |
+LL | function(0u32, 8u8)
+ | ^^^^^^^^^----^^^^^^
+ | |
+ | this argument influences the return type of `function`
+note: function defined here
+ --> $DIR/wrong-call-return-type-due-to-generic-arg.rs:1:4
+ |
+LL | fn function(x: T, y: bool) -> T {
+ | ^^^^^^^^ ---- -------
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/typeck/issue-46112.stderr b/tests/ui/typeck/issue-46112.stderr
index f488463ae3ce9..8f5ff51fbe100 100644
--- a/tests/ui/typeck/issue-46112.stderr
+++ b/tests/ui/typeck/issue-46112.stderr
@@ -8,6 +8,13 @@ LL | fn main() { test(Ok(())); }
|
= note: expected enum `Option<()>`
found unit type `()`
+help: the type constructed contains `()` due to the type of the argument passed
+ --> $DIR/issue-46112.rs:9:18
+ |
+LL | fn main() { test(Ok(())); }
+ | ^^^--^
+ | |
+ | this argument influences the type of `Ok`
note: tuple variant defined here
--> $SRC_DIR/core/src/result.rs:LL:COL
help: try wrapping the expression in `Some`
diff --git a/tests/ui/typeck/issue-84768.stderr b/tests/ui/typeck/issue-84768.stderr
index 00d23389720b9..09f3aee2d9ec5 100644
--- a/tests/ui/typeck/issue-84768.stderr
+++ b/tests/ui/typeck/issue-84768.stderr
@@ -14,6 +14,13 @@ LL | ::call_once(f, 1)
|
= note: expected tuple `(&mut u8,)`
found type `{integer}`
+help: the return type of this call is `{integer}` due to the type of the argument passed
+ --> $DIR/issue-84768.rs:7:5
+ |
+LL | ::call_once(f, 1)
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-^
+ | |
+ | this argument influences the return type of `FnOnce`
note: associated function defined here
--> $SRC_DIR/core/src/ops/function.rs:LL:COL
diff --git a/tests/ui/ufcs/ufcs-qpath-self-mismatch.stderr b/tests/ui/ufcs/ufcs-qpath-self-mismatch.stderr
index a2fe627868aeb..e85144a31ca96 100644
--- a/tests/ui/ufcs/ufcs-qpath-self-mismatch.stderr
+++ b/tests/ui/ufcs/ufcs-qpath-self-mismatch.stderr
@@ -21,6 +21,13 @@ LL | >::add(1u32, 2);
| |
| arguments to this function are incorrect
|
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/ufcs-qpath-self-mismatch.rs:7:5
+ |
+LL | >::add(1u32, 2);
+ | ^^^^^^^^^^^^^^^^^^^^^^^----^^^^
+ | |
+ | this argument influences the return type of `Add`
note: associated function defined here
--> $SRC_DIR/core/src/ops/arith.rs:LL:COL
help: change the type of the numeric literal from `u32` to `i32`
@@ -36,6 +43,13 @@ LL | >::add(1, 2u32);
| |
| arguments to this function are incorrect
|
+help: the return type of this call is `u32` due to the type of the argument passed
+ --> $DIR/ufcs-qpath-self-mismatch.rs:9:5
+ |
+LL | >::add(1, 2u32);
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^----^
+ | |
+ | this argument influences the return type of `Add`
note: associated function defined here
--> $SRC_DIR/core/src/ops/arith.rs:LL:COL
help: change the type of the numeric literal from `u32` to `i32`