Rollup merge of #131038 - onkoe:fix/adt_const_params_leak_118179, r=c…

…ompiler-errors Fix `adt_const_params` leaking `{type error}` in error msg Fixes the confusing diagnostic described in #118179. (users would see `{type error}` in some situations, which is pretty weird) `adt_const_params` tracking issue: #95174
rust-lang · Sep 30, 2024 · 5df1123 · 5df1123
2 parents dc1ccc5 + c5598d6
commit 5df1123
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diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -961,13 +961,20 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &hir::GenericParam<'_>) -> Result<(),
                         hir_ty.span,
                         "using raw pointers as const generic parameters is forbidden",
                     ),
-                    _ => tcx.dcx().struct_span_err(
-                        hir_ty.span,
-                        format!("`{}` is forbidden as the type of a const generic parameter", ty),
-                    ),
+                    _ => {
+                        // Avoid showing "{type error}" to users. See #118179.
+                        ty.error_reported()?;
+
+                        tcx.dcx().struct_span_err(
+                            hir_ty.span,
+                            format!(
+                                "`{ty}` is forbidden as the type of a const generic parameter",
+                            ),
+                        )
+                    }
                 };
 
-                diag.note("the only supported types are integers, `bool` and `char`");
+                diag.note("the only supported types are integers, `bool`, and `char`");
 
                 let cause = ObligationCause::misc(hir_ty.span, param.def_id);
                 let adt_const_params_feature_string =

diff --git a/tests/ui/const-generics/adt_const_params/suggest_feature_only_when_possible.stderr b/tests/ui/const-generics/adt_const_params/suggest_feature_only_when_possible.stderr
@@ -4,15 +4,15 @@ error: `&'static mut ()` is forbidden as the type of a const generic parameter
 LL | fn uwu_0<const N: &'static mut ()>() {}
    |                   ^^^^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: `&'static u32` is forbidden as the type of a const generic parameter
   --> $DIR/suggest_feature_only_when_possible.rs:15:19
    |
 LL | fn owo_0<const N: &'static u32>() {}
    |                   ^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]
@@ -28,7 +28,7 @@ error: `Meow` is forbidden as the type of a const generic parameter
 LL | fn meow_0<const N: Meow>() {}
    |                    ^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]
@@ -40,7 +40,7 @@ error: `&'static Meow` is forbidden as the type of a const generic parameter
 LL | fn meow_1<const N: &'static Meow>() {}
    |                    ^^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]
@@ -56,39 +56,39 @@ error: `[Meow; 100]` is forbidden as the type of a const generic parameter
 LL | fn meow_2<const N: [Meow; 100]>() {}
    |                    ^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: `(Meow, u8)` is forbidden as the type of a const generic parameter
   --> $DIR/suggest_feature_only_when_possible.rs:29:20
    |
 LL | fn meow_3<const N: (Meow, u8)>() {}
    |                    ^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: `(Meow, String)` is forbidden as the type of a const generic parameter
   --> $DIR/suggest_feature_only_when_possible.rs:34:20
    |
 LL | fn meow_4<const N: (Meow, String)>() {}
    |                    ^^^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: `String` is forbidden as the type of a const generic parameter
   --> $DIR/suggest_feature_only_when_possible.rs:38:19
    |
 LL | fn nya_0<const N: String>() {}
    |                   ^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: `Vec<u32>` is forbidden as the type of a const generic parameter
   --> $DIR/suggest_feature_only_when_possible.rs:40:19
    |
 LL | fn nya_1<const N: Vec<u32>>() {}
    |                   ^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: aborting due to 9 previous errors
 
diff --git a/tests/ui/const-generics/const-param-elided-lifetime.full.stderr b/tests/ui/const-generics/const-param-elided-lifetime.full.stderr
@@ -5,25 +5,25 @@ LL | struct A<const N: &u8>;
    |                   ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:14:15
+  --> $DIR/const-param-elided-lifetime.rs:13:15
    |
 LL | impl<const N: &u8> A<N> {
    |               ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:17:21
+  --> $DIR/const-param-elided-lifetime.rs:15:21
    |
 LL |     fn foo<const M: &u8>(&self) {}
    |                     ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:22:15
+  --> $DIR/const-param-elided-lifetime.rs:19:15
    |
 LL | impl<const N: &u8> B for A<N> {}
    |               ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:26:17
+  --> $DIR/const-param-elided-lifetime.rs:22:17
    |
 LL | fn bar<const N: &u8>() {}
    |                 ^ explicit lifetime name needed here

diff --git a/tests/ui/const-generics/const-param-elided-lifetime.min.stderr b/tests/ui/const-generics/const-param-elided-lifetime.min.stderr
@@ -5,109 +5,29 @@ LL | struct A<const N: &u8>;
    |                   ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:14:15
+  --> $DIR/const-param-elided-lifetime.rs:13:15
    |
 LL | impl<const N: &u8> A<N> {
    |               ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:17:21
+  --> $DIR/const-param-elided-lifetime.rs:15:21
    |
 LL |     fn foo<const M: &u8>(&self) {}
    |                     ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:22:15
+  --> $DIR/const-param-elided-lifetime.rs:19:15
    |
 LL | impl<const N: &u8> B for A<N> {}
    |               ^ explicit lifetime name needed here
 
 error[E0637]: `&` without an explicit lifetime name cannot be used here
-  --> $DIR/const-param-elided-lifetime.rs:26:17
+  --> $DIR/const-param-elided-lifetime.rs:22:17
    |
 LL | fn bar<const N: &u8>() {}
    |                 ^ explicit lifetime name needed here
 
-error: `&u8` is forbidden as the type of a const generic parameter
-  --> $DIR/const-param-elided-lifetime.rs:9:19
-   |
-LL | struct A<const N: &u8>;
-   |                   ^^^
-   |
-   = note: the only supported types are integers, `bool` and `char`
-help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
-   |
-LL + #![feature(adt_const_params)]
-   |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
-
-error: `&u8` is forbidden as the type of a const generic parameter
-  --> $DIR/const-param-elided-lifetime.rs:14:15
-   |
-LL | impl<const N: &u8> A<N> {
-   |               ^^^
-   |
-   = note: the only supported types are integers, `bool` and `char`
-help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
-   |
-LL + #![feature(adt_const_params)]
-   |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
-
-error: `&u8` is forbidden as the type of a const generic parameter
-  --> $DIR/const-param-elided-lifetime.rs:22:15
-   |
-LL | impl<const N: &u8> B for A<N> {}
-   |               ^^^
-   |
-   = note: the only supported types are integers, `bool` and `char`
-help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
-   |
-LL + #![feature(adt_const_params)]
-   |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
-
-error: `&u8` is forbidden as the type of a const generic parameter
-  --> $DIR/const-param-elided-lifetime.rs:26:17
-   |
-LL | fn bar<const N: &u8>() {}
-   |                 ^^^
-   |
-   = note: the only supported types are integers, `bool` and `char`
-help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
-   |
-LL + #![feature(adt_const_params)]
-   |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
-
-error: `&u8` is forbidden as the type of a const generic parameter
-  --> $DIR/const-param-elided-lifetime.rs:17:21
-   |
-LL |     fn foo<const M: &u8>(&self) {}
-   |                     ^^^
-   |
-   = note: the only supported types are integers, `bool` and `char`
-help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
-   |
-LL + #![feature(adt_const_params)]
-   |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
-
-error: aborting due to 10 previous errors
+error: aborting due to 5 previous errors
 
 For more information about this error, try `rustc --explain E0637`.
diff --git a/tests/ui/const-generics/const-param-elided-lifetime.rs b/tests/ui/const-generics/const-param-elided-lifetime.rs
@@ -8,23 +8,18 @@
 
 struct A<const N: &u8>;
 //~^ ERROR `&` without an explicit lifetime name cannot be used here
-//[min]~^^ ERROR `&u8` is forbidden
 trait B {}
 
 impl<const N: &u8> A<N> {
     //~^ ERROR `&` without an explicit lifetime name cannot be used here
-    //[min]~^^ ERROR `&u8` is forbidden
     fn foo<const M: &u8>(&self) {}
     //~^ ERROR `&` without an explicit lifetime name cannot be used here
-    //[min]~^^ ERROR `&u8` is forbidden
 }
 
 impl<const N: &u8> B for A<N> {}
 //~^ ERROR `&` without an explicit lifetime name cannot be used here
-//[min]~^^ ERROR `&u8` is forbidden
 
 fn bar<const N: &u8>() {}
 //~^ ERROR `&` without an explicit lifetime name cannot be used here
-//[min]~^^ ERROR `&u8` is forbidden
 
 fn main() {}
diff --git a/tests/ui/const-generics/const-param-type-depends-on-const-param.min.stderr b/tests/ui/const-generics/const-param-type-depends-on-const-param.min.stderr
@@ -20,7 +20,7 @@ error: `[u8; N]` is forbidden as the type of a const generic parameter
 LL | pub struct Dependent<const N: usize, const X: [u8; N]>([(); N]);
    |                                               ^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]
@@ -32,7 +32,7 @@ error: `[u8; N]` is forbidden as the type of a const generic parameter
 LL | pub struct SelfDependent<const N: [u8; N]>;
    |                                   ^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]

diff --git a/tests/ui/const-generics/default-ty-closure.stderr b/tests/ui/const-generics/default-ty-closure.stderr
@@ -4,7 +4,7 @@ error: using function pointers as const generic parameters is forbidden
 LL | struct X<const FN: fn() = { || {} }>;
    |                    ^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/float-generic.simple.stderr b/tests/ui/const-generics/float-generic.simple.stderr
@@ -4,7 +4,7 @@ error: `f32` is forbidden as the type of a const generic parameter
 LL | fn foo<const F: f32>() {}
    |                 ^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/fn-const-param-call.min.stderr b/tests/ui/const-generics/fn-const-param-call.min.stderr
@@ -4,15 +4,15 @@ error: using function pointers as const generic parameters is forbidden
 LL | struct Wrapper<const F: fn() -> u32>;
    |                         ^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: using function pointers as const generic parameters is forbidden
   --> $DIR/fn-const-param-call.rs:15:15
    |
 LL | impl<const F: fn() -> u32> Wrapper<F> {
    |               ^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/const-generics/fn-const-param-infer.min.stderr b/tests/ui/const-generics/fn-const-param-infer.min.stderr
@@ -4,7 +4,7 @@ error: using function pointers as const generic parameters is forbidden
 LL | struct Checked<const F: fn(usize) -> bool>;
    |                         ^^^^^^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error[E0308]: mismatched types
   --> $DIR/fn-const-param-infer.rs:33:25

diff --git a/tests/ui/const-generics/generic_const_exprs/array-size-in-generic-struct-param.min.stderr b/tests/ui/const-generics/generic_const_exprs/array-size-in-generic-struct-param.min.stderr
@@ -22,7 +22,7 @@ error: `Config` is forbidden as the type of a const generic parameter
 LL | struct B<const CFG: Config> {
    |                     ^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]

diff --git a/tests/ui/const-generics/generic_const_exprs/error_in_ty.stderr b/tests/ui/const-generics/generic_const_exprs/error_in_ty.stderr
@@ -12,7 +12,7 @@ error: `[usize; x]` is forbidden as the type of a const generic parameter
 LL | pub struct A<const z: [usize; x]> {}
    |                       ^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]

diff --git a/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr b/tests/ui/const-generics/generic_const_exprs/unevaluated-const-ice-119731.stderr
@@ -66,7 +66,7 @@ error: `[[usize; v4]; v4]` is forbidden as the type of a const generic parameter
 LL |     pub struct v17<const v10: usize, const v7: v11> {
    |                                                ^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]

diff --git a/tests/ui/const-generics/ice-118285-fn-ptr-value.stderr b/tests/ui/const-generics/ice-118285-fn-ptr-value.stderr
@@ -4,7 +4,7 @@ error: using function pointers as const generic parameters is forbidden
 LL | struct Checked<const F: fn(usize) -> bool>;
    |                         ^^^^^^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/intrinsics-type_name-as-const-argument.min.stderr b/tests/ui/const-generics/intrinsics-type_name-as-const-argument.min.stderr
@@ -13,7 +13,7 @@ error: `&'static str` is forbidden as the type of a const generic parameter
 LL | trait Trait<const S: &'static str> {}
    |                      ^^^^^^^^^^^^
    |
-   = note: the only supported types are integers, `bool` and `char`
+   = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]