WF-check struct field types at construction site

Rustc of course already WF-checked the field types at the definition
site, but for error tainting of consts to work properly, there needs to
be an error emitted at the use site. Previously, with no use-site error,
we proceeded with CTFE and ran into ICEs since we are running code with
type errors.

Emitting use-site errors also brings struct-like constructors more in
line with fn-like constructors since they already emit use-site errors
for WF issues.

4 files changed, 201 insertions, 1 deletions

diff --git a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs
new file mode 100644
index 00000000000..311f507d3c7
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs
@@ -0,0 +1,28 @@
+// This ensures we don't ICE in situations like rust-lang/rust#126272.
+
+#![feature(adt_const_params)]
+#![allow(incomplete_features)]
+
+use std::marker::ConstParamTy;
+
+#[derive(Debug, PartialEq, Eq, ConstParamTy)]
+//~^ ERROR the trait `ConstParamTy_`
+//~| ERROR the trait `ConstParamTy_`
+struct Foo {
+    nested: &'static Bar<dyn std::fmt::Debug>,
+    //~^ ERROR the size for values
+    //~| ERROR the size for values
+    //~| ERROR binary operation `==` cannot
+    //~| ERROR the trait bound `dyn Debug: Eq`
+    //~| ERROR the size for values
+}
+
+#[derive(Debug, PartialEq, Eq, ConstParamTy)]
+struct Bar<T>(T);
+
+struct Test<const F: Foo>;
+
+fn main() {
+    let x: Test<{ Foo { nested: &Bar(4) } }> = Test;
+    //~^ ERROR the size for values
+}
diff --git a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr
new file mode 100644
index 00000000000..1c30aa68e85
--- /dev/null
+++ b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr
@@ -0,0 +1,160 @@
+error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+   |
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`
+note: required by an implicit `Sized` bound in `Bar`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
+help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^  - ...if indirection were used here: `Box<T>`
+   |            |
+   |            this could be changed to `T: ?Sized`...
+
+error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:8:32
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                                ^^^^^^^^^^^^
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ----------------------------------------- this field does not implement `ConstParamTy_`
+   |
+   = note: this error originates in the derive macro `ConstParamTy` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:8:32
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                                ^^^^^^^^^^^^
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ----------------------------------------- this field does not implement `ConstParamTy_`
+   |
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Eq`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+   |
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Sized`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+   |
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): UnsizedConstParamTy`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+   |
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = note: this error originates in the derive macro `ConstParamTy` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |          ----- in this derive macro expansion
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`, which is required by `&&'static Bar<(dyn Debug + 'static)>: Debug`
+   = help: the trait `Debug` is implemented for `Bar<T>`
+note: required for `Bar<(dyn Debug + 'static)>` to implement `Debug`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:10
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |          ^^^^^
+LL | struct Bar<T>(T);
+   |            - unsatisfied trait bound introduced in this `derive` macro
+   = note: 2 redundant requirements hidden
+   = note: required for `&&'static Bar<(dyn Debug + 'static)>` to implement `Debug`
+   = note: required for the cast from `&&&'static Bar<(dyn Debug + 'static)>` to `&dyn Debug`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0369]: binary operation `==` cannot be applied to type `&Bar<dyn Debug>`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                 --------- in this derive macro expansion
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this error originates in the derive macro `PartialEq` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `dyn Debug: Eq` is not satisfied
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                            -- in this derive macro expansion
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Eq` is not implemented for `dyn Debug`, which is required by `&'static Bar<dyn Debug>: Eq`
+   |
+   = help: the trait `Eq` is implemented for `Bar<T>`
+note: required for `Bar<dyn Debug>` to implement `Eq`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:28
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                            ^^ unsatisfied trait bound introduced in this `derive` macro
+   = note: 1 redundant requirement hidden
+   = note: required for `&'static Bar<dyn Debug>` to implement `Eq`
+note: required by a bound in `AssertParamIsEq`
+  --> $SRC_DIR/core/src/cmp.rs:LL:COL
+   = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the size for values of type `dyn Debug` cannot be known at compilation time
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+   |
+LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
+   |                            -- in this derive macro expansion
+...
+LL |     nested: &'static Bar<dyn std::fmt::Debug>,
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `dyn Debug`
+note: required by an implicit `Sized` bound in `Bar`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
+help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^  - ...if indirection were used here: `Box<T>`
+   |            |
+   |            this could be changed to `T: ?Sized`...
+   = note: this error originates in the derive macro `Eq` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:26:33
+   |
+LL |     let x: Test<{ Foo { nested: &Bar(4) } }> = Test;
+   |                                 ^^^^^^^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`
+note: required by an implicit `Sized` bound in `Bar`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
+help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+   |
+LL | struct Bar<T>(T);
+   |            ^  - ...if indirection were used here: `Box<T>`
+   |            |
+   |            this could be changed to `T: ?Sized`...
+
+error: aborting due to 8 previous errors
+
+Some errors have detailed explanations: E0204, E0277, E0369.
+For more information about an error, try `rustc --explain E0204`.
diff --git a/tests/ui/const-generics/generic_const_exprs/no_where_clause.rs b/tests/ui/const-generics/generic_const_exprs/no_where_clause.rs
index 77cce66e4ec..53230469491 100644
--- a/tests/ui/const-generics/generic_const_exprs/no_where_clause.rs
+++ b/tests/ui/const-generics/generic_const_exprs/no_where_clause.rs
@@ -17,6 +17,7 @@ impl<const N: usize> Example<N> {
       a: [0.; N],
       b: [0.; complex_maths(N)],
       //~^ ERROR: unconstrained generic constant
+      //~| ERROR: unconstrained generic constant
     }
   }
 }
diff --git a/tests/ui/const-generics/generic_const_exprs/no_where_clause.stderr b/tests/ui/const-generics/generic_const_exprs/no_where_clause.stderr
index a2680eac039..88fc68a4d1b 100644
--- a/tests/ui/const-generics/generic_const_exprs/no_where_clause.stderr
+++ b/tests/ui/const-generics/generic_const_exprs/no_where_clause.stderr
@@ -10,6 +10,17 @@ LL | pub struct Example<const N: usize> where [(); complex_maths(N)]: {
    |                                    +++++++++++++++++++++++++++++
 
 error: unconstrained generic constant
+  --> $DIR/no_where_clause.rs:18:10
+   |
+LL |       b: [0.; complex_maths(N)],
+   |          ^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try adding a `where` bound
+   |
+LL |   pub fn new() -> Self where [(); complex_maths(N)]: {
+   |                        +++++++++++++++++++++++++++++
+
+error: unconstrained generic constant
   --> $DIR/no_where_clause.rs:18:15
    |
 LL |       b: [0.; complex_maths(N)],
@@ -20,5 +31,5 @@ help: try adding a `where` bound
 LL |   pub fn new() -> Self where [(); complex_maths(N)]: {
    |                        +++++++++++++++++++++++++++++
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors