Auto merge of #85767 - lqd:stackless_span_stacks, r=oli-obk

A bit more polish on const eval errors

This PR adds a bit more polish to the const eval errors:
- a slight improvement to the PME messages from #85633: I mentioned there that the erroneous item's paths were dependent on the environment, and could be displayed fully qualified or not. This can obscure the items when they come from a dependency. This PR uses the pretty-printing code ensuring the items' paths are not trimmed.
- whenever there are generics involved in an item where const evaluation errors out, the error message now displays the instance and its const arguments, so that we can see which instantiated item and compile-time values lead to the error.

So we get this slight improvement for our beloved `stdarch` example, on nightly:
```
error[E0080]: evaluation of constant value failed
 --> ./stdarch/crates/core_arch/src/macros.rs:8:9
  |
8 |         assert!(IMM >= MIN && IMM <= MAX, "IMM value not in expected range");
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'IMM value not in expected range', /rustc/9111b8ae9793f18179a1336417618fc07a9cac85/library/core/src/../../stdarch/crates/core_arch/src/macros.rs:8:9
  |
```

to this PR's:

```
error[E0080]: evaluation of `core::core_arch::macros::ValidateConstImm::<51_i32, 0_i32, 15_i32>::VALID` failed
 --> ./stdarch/crates/core_arch/src/macros.rs:8:9
  |
8 |         assert!(IMM >= MIN && IMM <= MAX, "IMM value not in expected range");
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'IMM value not in expected range', ./stdarch/crates/core_arch/src/macros.rs:8:9
  |
```

with this PR.

Of course this is an idea from Oli, so maybe r? `@oli-obk` if they have the time.

9 files changed, 15 insertions, 14 deletions

diff --git a/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.rs b/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.rs
index 3da4688702c..8167d785d7a 100644
--- a/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.rs
+++ b/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.rs
@@ -2,7 +2,7 @@
 #![allow(incomplete_features)]
 
 fn test<const N: usize>() -> [u8; N - 1] {
-    //~^ ERROR evaluation of constant
+    //~^ ERROR evaluation of `test::<0_usize>::{constant#0}` failed
     todo!()
 }
 
diff --git a/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.stderr b/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.stderr
index 25af18eb162..31ccf979694 100644
--- a/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.stderr
+++ b/src/test/ui/const-generics/const_evaluatable_checked/from-sig-fail.stderr
@@ -1,4 +1,4 @@
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `test::<0_usize>::{constant#0}` failed
   --> $DIR/from-sig-fail.rs:4:35
    |
 LL | fn test<const N: usize>() -> [u8; N - 1] {
diff --git a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.full.stderr b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.full.stderr
index acf0a52ce5b..1f2313a6028 100644
--- a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.full.stderr
+++ b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.full.stderr
@@ -1,10 +1,10 @@
-error[E0080]: evaluation of constant value failed
-  --> $DIR/simple_fail.rs:9:48
+error[E0080]: evaluation of `test::<0_usize>::{constant#0}` failed
+  --> $DIR/simple_fail.rs:10:48
    |
 LL | fn test<const N: usize>() -> Arr<N> where [u8; N - 1]: Sized {
    |                                                ^^^^^ attempt to compute `0_usize - 1_usize`, which would overflow
 
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `Arr::<0_usize>::{constant#0}` failed
   --> $DIR/simple_fail.rs:6:33
    |
 LL | type Arr<const N: usize> = [u8; N - 1];
diff --git a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.min.stderr b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.min.stderr
index fe5463f8acc..1aa66f9a8ba 100644
--- a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.min.stderr
+++ b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.min.stderr
@@ -8,7 +8,7 @@ LL | type Arr<const N: usize> = [u8; N - 1];
    = help: use `#![feature(const_generics)]` and `#![feature(const_evaluatable_checked)]` to allow generic const expressions
 
 error: generic parameters may not be used in const operations
-  --> $DIR/simple_fail.rs:9:48
+  --> $DIR/simple_fail.rs:10:48
    |
 LL | fn test<const N: usize>() -> Arr<N> where [u8; N - 1]: Sized {
    |                                                ^ cannot perform const operation using `N`
diff --git a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.rs b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.rs
index c9535d04244..f08d2495b4d 100644
--- a/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.rs
+++ b/src/test/ui/const-generics/const_evaluatable_checked/simple_fail.rs
@@ -3,12 +3,13 @@
 #![cfg_attr(full, feature(const_evaluatable_checked))]
 #![allow(incomplete_features)]
 
-type Arr<const N: usize> = [u8; N - 1]; //[full]~ ERROR evaluation of constant
+type Arr<const N: usize> = [u8; N - 1];
 //[min]~^ ERROR generic parameters may not be used in const operations
+//[full]~^^ ERROR evaluation of `Arr::<0_usize>::{constant#0}` failed
 
 fn test<const N: usize>() -> Arr<N> where [u8; N - 1]: Sized {
 //[min]~^ ERROR generic parameters may not be used in const operations
-//[full]~^^ ERROR evaluation of constant
+//[full]~^^ ERROR evaluation of `test::<0_usize>::{constant#0}` failed
     todo!()
 }
 
diff --git a/src/test/ui/consts/const-eval/issue-50814-2.stderr b/src/test/ui/consts/const-eval/issue-50814-2.stderr
index 0c520165496..d34ac773da2 100644
--- a/src/test/ui/consts/const-eval/issue-50814-2.stderr
+++ b/src/test/ui/consts/const-eval/issue-50814-2.stderr
@@ -10,7 +10,7 @@ LL |     const BAR: usize = [5, 6, 7][T::BOO];
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `foo::<()>` failed
   --> $DIR/issue-50814-2.rs:19:6
    |
 LL |     &<A<T> as Foo<T>>::BAR
diff --git a/src/test/ui/consts/const-eval/issue-50814.stderr b/src/test/ui/consts/const-eval/issue-50814.stderr
index cf82d1eef3e..dd8d6bf839a 100644
--- a/src/test/ui/consts/const-eval/issue-50814.stderr
+++ b/src/test/ui/consts/const-eval/issue-50814.stderr
@@ -10,7 +10,7 @@ LL |     const MAX: u8 = A::MAX + B::MAX;
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `foo::<i32>` failed
   --> $DIR/issue-50814.rs:21:6
    |
 LL |     &Sum::<U8,U8>::MAX
diff --git a/src/test/ui/consts/const-eval/issue-85155.stderr b/src/test/ui/consts/const-eval/issue-85155.stderr
index 0a1edfb8a33..c36d7c17215 100644
--- a/src/test/ui/consts/const-eval/issue-85155.stderr
+++ b/src/test/ui/consts/const-eval/issue-85155.stderr
@@ -1,10 +1,10 @@
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `post_monomorphization_error::ValidateConstImm::<2_i32, 0_i32, 1_i32>::VALID` failed
   --> $DIR/auxiliary/post_monomorphization_error.rs:7:17
    |
 LL |         let _ = 1 / ((IMM >= MIN && IMM <= MAX) as usize);
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempt to divide `1_usize` by zero
 
-note: the above error was encountered while instantiating `fn stdarch_intrinsic::<2_i32>`
+note: the above error was encountered while instantiating `fn post_monomorphization_error::stdarch_intrinsic::<2_i32>`
   --> $DIR/issue-85155.rs:19:5
    |
 LL |     post_monomorphization_error::stdarch_intrinsic::<2>();
diff --git a/src/test/ui/mir/issue-80742.stderr b/src/test/ui/mir/issue-80742.stderr
index 8400aab308e..961234cf7e8 100644
--- a/src/test/ui/mir/issue-80742.stderr
+++ b/src/test/ui/mir/issue-80742.stderr
@@ -1,4 +1,4 @@
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `Inline::<dyn std::fmt::Debug>::{constant#0}` failed
   --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
    |
 LL |     intrinsics::size_of::<T>()
@@ -35,7 +35,7 @@ LL |   pub trait Debug {
    = note: the following trait bounds were not satisfied:
            `dyn Debug: Sized`
 
-error[E0080]: evaluation of constant value failed
+error[E0080]: evaluation of `Inline::<dyn std::fmt::Debug>::{constant#0}` failed
   --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
    |
 LL |     intrinsics::size_of::<T>()