Rollup merge of #133954 - oli-obk:push-lxrmszqzszzu, r=jieyouxu

Hide errors whose suggestions would contain error constants or types

best reviewed commit-by-commit.

This is work towards cleaning up everything around `lit_to_const` and its mir equivalent.

fixes #123809

Author: matthiaskrgr

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -998,6 +998,9 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                                         self.lower_const_arg(ct, FeedConstTy::No).into()
                                     }
                                 };
+                                if term.references_error() {
+                                    continue;
+                                }
                                 // FIXME(#97583): This isn't syntactically well-formed!
                                 where_bounds.push(format!(
                                     "        T: {trait}::{assoc_name} = {term}",

compiler/rustc_mir_build/src/thir/constant.rs

@@ -2,7 +2,7 @@ use rustc_ast as ast;
 use rustc_hir::LangItem;
 use rustc_middle::bug;
 use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
-use rustc_middle::ty::{self, ScalarInt, TyCtxt};
+use rustc_middle::ty::{self, ScalarInt, TyCtxt, TypeVisitableExt as _};
 use tracing::trace;
 
 use crate::build::parse_float_into_scalar;
@@ -13,6 +13,10 @@ pub(crate) fn lit_to_const<'tcx>(
 ) -> Result<ty::Const<'tcx>, LitToConstError> {
     let LitToConstInput { lit, ty, neg } = lit_input;
 
+    if let Err(guar) = ty.error_reported() {
+        return Ok(ty::Const::new_error(tcx, guar));
+    }
+
     let trunc = |n| {
         let width = match tcx.layout_of(ty::TypingEnv::fully_monomorphized().as_query_input(ty)) {
             Ok(layout) => layout.size,

tests/crashes/123809.rs

@@ -26,12 +26,6 @@ LL | trait Parent2 { const C: &'static str; }
 LL |
 LL | fn take1(_: impl Trait1<C = "?">) {}
    |                         ^^^^^^^ ambiguous associated constant `C`
-   |
-   = help: consider introducing a new type parameter `T` and adding `where` constraints:
-               where
-                   T: Trait1,
-                   T: Parent2::C = "?",
-                   T: Parent1::C = "?"
 
 error: aborting due to 2 previous errors
 

tests/ui/associated-consts/assoc-const-eq-ambiguity.stderr

@@ -3,15 +3,11 @@ trait Foo<const N: Bar<2>> {
     //~^ WARN trait objects without an explicit `dyn` are deprecated
     //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
     //~| ERROR cycle detected when computing type of `Foo::N`
-    //~| ERROR the trait `Foo` cannot be made into an object
-    //~| ERROR `(dyn Bar<2> + 'static)` is forbidden as the type of a const generic parameter
     fn func() {}
 }
 
 trait Bar<const M: Foo<2>> {}
 //~^ WARN trait objects without an explicit `dyn` are deprecated
 //~| WARN this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
-//~| ERROR the trait `Foo` cannot be made into an object
-//~| ERROR `(dyn Foo<2> + 'static)` is forbidden as the type of a const generic parameter
 
 fn main() {}

tests/ui/wf/ice-hir-wf-check-anon-const-issue-122989.rs

@@ -13,7 +13,7 @@ LL | trait Foo<const N: dyn Bar<2>> {
    |                    +++
 
 warning: trait objects without an explicit `dyn` are deprecated
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:11:20
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:9:20
    |
 LL | trait Bar<const M: Foo<2>> {}
    |                    ^^^^^^
@@ -32,7 +32,7 @@ LL | trait Foo<const N: Bar<2>> {
    |           ^^^^^^^^^^^^^^^
    |
 note: ...which requires computing type of `Bar::M`...
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:11:11
+  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:9:11
    |
 LL | trait Bar<const M: Foo<2>> {}
    |           ^^^^^^^^^^^^^^^
@@ -44,69 +44,6 @@ LL | trait Foo<const N: Bar<2>> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:2:24
-   |
-LL | trait Foo<const N: Bar<2>> {
-   |                        ^ `Foo` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:8:8
-   |
-LL | trait Foo<const N: Bar<2>> {
-   |       --- this trait cannot be made into an object...
-...
-LL |     fn func() {}
-   |        ^^^^ ...because associated function `func` has no `self` parameter
-help: consider turning `func` into a method by giving it a `&self` argument
-   |
-LL |     fn func(&self) {}
-   |             +++++
-help: alternatively, consider constraining `func` so it does not apply to trait objects
-   |
-LL |     fn func() where Self: Sized {}
-   |               +++++++++++++++++
-
-error: `(dyn Bar<2> + 'static)` is forbidden as the type of a const generic parameter
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:2:20
-   |
-LL | trait Foo<const N: Bar<2>> {
-   |                    ^^^^^^
-   |
-   = note: the only supported types are integers, `bool`, and `char`
-
-error[E0038]: the trait `Foo` cannot be made into an object
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:11:11
-   |
-LL | trait Bar<const M: Foo<2>> {}
-   |           ^^^^^^^^^^^^^^^ `Foo` cannot be made into an object
-   |
-note: for a trait to be "dyn-compatible" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:8:8
-   |
-LL | trait Foo<const N: Bar<2>> {
-   |       --- this trait cannot be made into an object...
-...
-LL |     fn func() {}
-   |        ^^^^ ...because associated function `func` has no `self` parameter
-help: consider turning `func` into a method by giving it a `&self` argument
-   |
-LL |     fn func(&self) {}
-   |             +++++
-help: alternatively, consider constraining `func` so it does not apply to trait objects
-   |
-LL |     fn func() where Self: Sized {}
-   |               +++++++++++++++++
-
-error: `(dyn Foo<2> + 'static)` is forbidden as the type of a const generic parameter
-  --> $DIR/ice-hir-wf-check-anon-const-issue-122989.rs:11:20
-   |
-LL | trait Bar<const M: Foo<2>> {}
-   |                    ^^^^^^
-   |
-   = note: the only supported types are integers, `bool`, and `char`
-
-error: aborting due to 5 previous errors; 2 warnings emitted
+error: aborting due to 1 previous error; 2 warnings emitted
 
-Some errors have detailed explanations: E0038, E0391.
-For more information about an error, try `rustc --explain E0038`.
+For more information about this error, try `rustc --explain E0391`.