Rollup merge of rust-lang#113005 - compiler-errors:dont-query-normali…

…ze, r=cjgillot

Don't call `query_normalize` when reporting similar impls

Firstly, It's sketchy to be using `query_normalize` at all during HIR typeck -- it's asking for an ICE 😅. Secondly, we're normalizing an impl trait ref that potentially has parameter types in `ty::ParamEnv::empty()`, which is kinda sketchy as well.

The only UI test change from removing this normalization is that we don't evaluate anonymous constants in impls, which end up giving us really ugly suggestions:

```
error[E0277]: the trait bound `[X; 35]: Default` is not satisfied
 --> /home/gh-compiler-errors/test.rs:4:5
  |
4 |     <[X; 35] as Default>::default();
  |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `[X; 35]`
  |
  = help: the following other types implement trait `Default`:
            &[T]
            &mut [T]
            [T; 32]
            [T; core::::array::{impl#30}::{constant#0}]
            [T; core::::array::{impl#31}::{constant#0}]
            [T; core::::array::{impl#32}::{constant#0}]
            [T; core::::array::{impl#33}::{constant#0}]
            [T; core::::array::{impl#34}::{constant#0}]
          and 27 others
```

So just fold the impls with a `BottomUpFolder` that calls `ty::Const::eval`. This doesn't work totally correctly with generic-const-exprs, but it's fine for stable code, and this is error reporting after all.

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -12,7 +12,6 @@ use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::{self, InferCtxt};
 use crate::solve::{GenerateProofTree, InferCtxtEvalExt, UseGlobalCache};
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
-use crate::traits::query::normalize::QueryNormalizeExt as _;
 use crate::traits::specialize::to_pretty_impl_header;
 use crate::traits::NormalizeExt;
 use on_unimplemented::{AppendConstMessage, OnUnimplementedNote, TypeErrCtxtExt as _};
@@ -33,7 +32,7 @@ use rustc_middle::traits::solve::Goal;
 use rustc_middle::traits::{DefiningAnchor, SelectionOutputTypeParameterMismatch};
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
+use rustc_middle::ty::fold::{BottomUpFolder, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::print::{with_forced_trimmed_paths, FmtPrinter, Print};
 use rustc_middle::ty::{
     self, SubtypePredicate, ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt, TypeFoldable,
@@ -63,7 +62,7 @@ pub enum CandidateSimilarity {
     Fuzzy { ignoring_lifetimes: bool },
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct ImplCandidate<'tcx> {
     pub trait_ref: ty::TraitRef<'tcx>,
     pub similarity: CandidateSimilarity,
@@ -1941,10 +1940,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         other: bool,
     ) -> bool {
         let other = if other { "other " } else { "" };
-        let report = |mut candidates: Vec<TraitRef<'tcx>>, err: &mut Diagnostic| {
-            candidates.sort();
-            candidates.dedup();
-            let len = candidates.len();
+        let report = |candidates: Vec<TraitRef<'tcx>>, err: &mut Diagnostic| {
             if candidates.is_empty() {
                 return false;
             }
@@ -1973,26 +1969,31 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 candidates.iter().map(|c| c.print_only_trait_path().to_string()).collect();
             traits.sort();
             traits.dedup();
+            // FIXME: this could use a better heuristic, like just checking
+            // that substs[1..] is the same.
+            let all_traits_equal = traits.len() == 1;
 
-            let mut candidates: Vec<String> = candidates
+            let candidates: Vec<String> = candidates
                 .into_iter()
                 .map(|c| {
-                    if traits.len() == 1 {
+                    if all_traits_equal {
                         format!("\n  {}", c.self_ty())
                     } else {
                         format!("\n  {}", c)
                     }
                 })
                 .collect();
 
-            candidates.sort();
-            candidates.dedup();
             let end = if candidates.len() <= 9 { candidates.len() } else { 8 };
             err.help(format!(
                 "the following {other}types implement trait `{}`:{}{}",
                 trait_ref.print_only_trait_path(),
                 candidates[..end].join(""),
-                if len > 9 { format!("\nand {} others", len - 8) } else { String::new() }
+                if candidates.len() > 9 {
+                    format!("\nand {} others", candidates.len() - 8)
+                } else {
+                    String::new()
+                }
             ));
             true
         };
@@ -2006,7 +2007,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 // Mentioning implementers of `Copy`, `Debug` and friends is not useful.
                 return false;
             }
-            let normalized_impl_candidates: Vec<_> = self
+            let mut impl_candidates: Vec<_> = self
                 .tcx
                 .all_impls(def_id)
                 // Ignore automatically derived impls and `!Trait` impls.
@@ -2033,7 +2034,10 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     }
                 })
                 .collect();
-            return report(normalized_impl_candidates, err);
+
+            impl_candidates.sort();
+            impl_candidates.dedup();
+            return report(impl_candidates, err);
         }
 
         // Sort impl candidates so that ordering is consistent for UI tests.
@@ -2042,27 +2046,25 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         //
         // Prefer more similar candidates first, then sort lexicographically
         // by their normalized string representation.
-        let mut normalized_impl_candidates_and_similarities = impl_candidates
+        let mut impl_candidates: Vec<_> = impl_candidates
             .iter()
-            .copied()
-            .map(|ImplCandidate { trait_ref, similarity }| {
-                // FIXME(compiler-errors): This should be using `NormalizeExt::normalize`
-                let normalized = self
-                    .at(&ObligationCause::dummy(), ty::ParamEnv::empty())
-                    .query_normalize(trait_ref)
-                    .map_or(trait_ref, |normalized| normalized.value);
-                (similarity, normalized)
+            .cloned()
+            .map(|mut cand| {
+                // Fold the consts so that they shows up as, e.g., `10`
+                // instead of `core::::array::{impl#30}::{constant#0}`.
+                cand.trait_ref = cand.trait_ref.fold_with(&mut BottomUpFolder {
+                    tcx: self.tcx,
+                    ty_op: |ty| ty,
+                    lt_op: |lt| lt,
+                    ct_op: |ct| ct.eval(self.tcx, ty::ParamEnv::empty()),
+                });
+                cand
             })
-            .collect::<Vec<_>>();
-        normalized_impl_candidates_and_similarities.sort();
-        normalized_impl_candidates_and_similarities.dedup();
-
-        let normalized_impl_candidates = normalized_impl_candidates_and_similarities
-            .into_iter()
-            .map(|(_, normalized)| normalized)
-            .collect::<Vec<_>>();
+            .collect();
+        impl_candidates.sort_by_key(|cand| (cand.similarity, cand.trait_ref));
+        impl_candidates.dedup();
 
-        report(normalized_impl_candidates, err)
+        report(impl_candidates.into_iter().map(|cand| cand.trait_ref).collect(), err)
     }
 
     fn report_similar_impl_candidates_for_root_obligation(

tests/ui/binop/binop-mul-i32-f32.stderr

@@ -6,10 +6,10 @@ LL |     x * y
    |
    = help: the trait `Mul<f32>` is not implemented for `i32`
    = help: the following other types implement trait `Mul<Rhs>`:
+             <i32 as Mul>
+             <i32 as Mul<&i32>>
              <&'a i32 as Mul<i32>>
              <&i32 as Mul<&i32>>
-             <i32 as Mul<&i32>>
-             <i32 as Mul>
 
 error: aborting due to previous error
 

tests/ui/binop/shift-various-bad-types.stderr

@@ -6,14 +6,14 @@ LL |     22 >> p.char;
    |
    = help: the trait `Shr<char>` is not implemented for `{integer}`
    = help: the following other types implement trait `Shr<Rhs>`:
-             <&'a i128 as Shr<i128>>
-             <&'a i128 as Shr<i16>>
-             <&'a i128 as Shr<i32>>
-             <&'a i128 as Shr<i64>>
-             <&'a i128 as Shr<i8>>
-             <&'a i128 as Shr<isize>>
-             <&'a i128 as Shr<u128>>
-             <&'a i128 as Shr<u16>>
+             <isize as Shr>
+             <isize as Shr<i8>>
+             <isize as Shr<i16>>
+             <isize as Shr<i32>>
+             <isize as Shr<i64>>
+             <isize as Shr<i128>>
+             <isize as Shr<usize>>
+             <isize as Shr<u8>>
            and 568 others
 
 error[E0277]: no implementation for `{integer} >> &str`
@@ -24,14 +24,14 @@ LL |     22 >> p.str;
    |
    = help: the trait `Shr<&str>` is not implemented for `{integer}`
    = help: the following other types implement trait `Shr<Rhs>`:
-             <&'a i128 as Shr<i128>>
-             <&'a i128 as Shr<i16>>
-             <&'a i128 as Shr<i32>>
-             <&'a i128 as Shr<i64>>
-             <&'a i128 as Shr<i8>>
-             <&'a i128 as Shr<isize>>
-             <&'a i128 as Shr<u128>>
-             <&'a i128 as Shr<u16>>
+             <isize as Shr>
+             <isize as Shr<i8>>
+             <isize as Shr<i16>>
+             <isize as Shr<i32>>
+             <isize as Shr<i64>>
+             <isize as Shr<i128>>
+             <isize as Shr<usize>>
+             <isize as Shr<u8>>
            and 568 others
 
 error[E0277]: no implementation for `{integer} >> &Panolpy`
@@ -42,14 +42,14 @@ LL |     22 >> p;
    |
    = help: the trait `Shr<&Panolpy>` is not implemented for `{integer}`
    = help: the following other types implement trait `Shr<Rhs>`:
-             <&'a i128 as Shr<i128>>
-             <&'a i128 as Shr<i16>>
-             <&'a i128 as Shr<i32>>
-             <&'a i128 as Shr<i64>>
-             <&'a i128 as Shr<i8>>
-             <&'a i128 as Shr<isize>>
-             <&'a i128 as Shr<u128>>
-             <&'a i128 as Shr<u16>>
+             <isize as Shr>
+             <isize as Shr<i8>>
+             <isize as Shr<i16>>
+             <isize as Shr<i32>>
+             <isize as Shr<i64>>
+             <isize as Shr<i128>>
+             <isize as Shr<usize>>
+             <isize as Shr<u8>>
            and 568 others
 
 error[E0308]: mismatched types

tests/ui/const-generics/exhaustive-value.stderr

@@ -6,13 +6,13 @@ LL |     <() as Foo<N>>::test()
    |
    = help: the following other types implement trait `Foo<N>`:
              <() as Foo<0>>
-             <() as Foo<100>>
-             <() as Foo<101>>
-             <() as Foo<102>>
-             <() as Foo<103>>
-             <() as Foo<104>>
-             <() as Foo<105>>
-             <() as Foo<106>>
+             <() as Foo<1>>
+             <() as Foo<2>>
+             <() as Foo<3>>
+             <() as Foo<4>>
+             <() as Foo<5>>
+             <() as Foo<6>>
+             <() as Foo<7>>
            and 248 others
 
 error: aborting due to previous error

tests/ui/const-generics/generic_arg_infer/issue-91614.stderr

@@ -6,11 +6,11 @@ LL |     let y = Mask::<_, _>::splat(false);
    |
    = note: cannot satisfy `_: MaskElement`
    = help: the following types implement trait `MaskElement`:
+             isize
+             i8
              i16
              i32
              i64
-             i8
-             isize
 note: required by a bound in `Mask::<T, LANES>::splat`
   --> $SRC_DIR/core/src/../../portable-simd/crates/core_simd/src/masks.rs:LL:COL
 help: consider giving `y` an explicit type, where the type for type parameter `T` is specified

tests/ui/const-generics/issues/issue-67185-2.stderr

@@ -5,8 +5,8 @@ LL |     <u8 as Baz>::Quaks: Bar,
    |     ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `[u16; 3]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
    = help: see issue #48214
    = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
 
@@ -17,8 +17,8 @@ LL |     [<u8 as Baz>::Quaks; 2]: Bar,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Bar` is not implemented for `[[u16; 3]; 2]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
    = help: see issue #48214
    = help: add `#![feature(trivial_bounds)]` to the crate attributes to enable
 
@@ -29,8 +29,8 @@ LL | impl Foo for FooImpl {}
    |      ^^^ the trait `Bar` is not implemented for `[u16; 3]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
 note: required by a bound in `Foo`
   --> $DIR/issue-67185-2.rs:15:25
    |
@@ -47,8 +47,8 @@ LL | impl Foo for FooImpl {}
    |      ^^^ the trait `Bar` is not implemented for `[[u16; 3]; 2]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
 note: required by a bound in `Foo`
   --> $DIR/issue-67185-2.rs:14:30
    |
@@ -65,8 +65,8 @@ LL | fn f(_: impl Foo) {}
    |              ^^^ the trait `Bar` is not implemented for `[[u16; 3]; 2]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
 note: required by a bound in `Foo`
   --> $DIR/issue-67185-2.rs:14:30
    |
@@ -83,8 +83,8 @@ LL | fn f(_: impl Foo) {}
    |              ^^^ the trait `Bar` is not implemented for `[u16; 3]`
    |
    = help: the following other types implement trait `Bar`:
-             [[u16; 3]; 3]
              [u16; 4]
+             [[u16; 3]; 3]
 note: required by a bound in `Foo`
   --> $DIR/issue-67185-2.rs:15:25
    |

tests/ui/consts/const-eval/const-eval-overflow-3b.stderr

@@ -12,10 +12,10 @@ LL |     = [0; (i8::MAX + 1u8) as usize];
    |
    = help: the trait `Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
+             <i8 as Add>
+             <i8 as Add<&i8>>
              <&'a i8 as Add<i8>>
              <&i8 as Add<&i8>>
-             <i8 as Add<&i8>>
-             <i8 as Add>
 
 error: aborting due to 2 previous errors
 

tests/ui/consts/const-eval/const-eval-overflow-4b.stderr

@@ -12,10 +12,10 @@ LL |     : [u32; (i8::MAX as i8 + 1u8) as usize]
    |
    = help: the trait `Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
+             <i8 as Add>
+             <i8 as Add<&i8>>
              <&'a i8 as Add<i8>>
              <&i8 as Add<&i8>>
-             <i8 as Add<&i8>>
-             <i8 as Add>
 
 error[E0604]: only `u8` can be cast as `char`, not `i8`
   --> $DIR/const-eval-overflow-4b.rs:22:13

tests/ui/consts/missing-larger-array-impl.rs

@@ -0,0 +1,9 @@
+struct X;
+
+// Make sure that we show the impl trait refs in the help message with
+// their evaluated constants, rather than `core::::array::{impl#30}::{constant#0}`
+
+fn main() {
+    <[X; 35] as Default>::default();
+    //~^ ERROR the trait bound `[X; 35]: Default` is not satisfied
+}

tests/ui/consts/missing-larger-array-impl.stderr

@@ -0,0 +1,20 @@
+error[E0277]: the trait bound `[X; 35]: Default` is not satisfied
+  --> $DIR/missing-larger-array-impl.rs:7:5
+   |
+LL |     <[X; 35] as Default>::default();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `[X; 35]`
+   |
+   = help: the following other types implement trait `Default`:
+             [T; 0]
+             [T; 1]
+             [T; 2]
+             [T; 3]
+             [T; 4]
+             [T; 5]
+             [T; 6]
+             [T; 7]
+           and 27 others
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.

tests/ui/consts/too_generic_eval_ice.stderr

@@ -22,14 +22,14 @@ LL |         [5; Self::HOST_SIZE] == [6; 0]
    |
    = help: the trait `PartialEq<[{integer}; 0]>` is not implemented for `[{integer}; Self::HOST_SIZE]`
    = help: the following other types implement trait `PartialEq<Rhs>`:
-             <&[B] as PartialEq<[A; N]>>
-             <&[T] as PartialEq<Vec<U, A>>>
-             <&mut [B] as PartialEq<[A; N]>>
-             <&mut [T] as PartialEq<Vec<U, A>>>
-             <[A; N] as PartialEq<&[B]>>
-             <[A; N] as PartialEq<&mut [B]>>
              <[A; N] as PartialEq<[B; N]>>
              <[A; N] as PartialEq<[B]>>
+             <[A; N] as PartialEq<&[B]>>
+             <[A; N] as PartialEq<&mut [B]>>
+             <[T] as PartialEq<Vec<U, A>>>
+             <[A] as PartialEq<[B]>>
+             <[B] as PartialEq<[A; N]>>
+             <&[T] as PartialEq<Vec<U, A>>>
            and 3 others
 
 error: aborting due to 3 previous errors