Add regression test for #103369

tests/ui/coherence/const-errs-dont-conflict-103369.rs

@@ -0,0 +1,14 @@
+// #103369: don't complain about conflicting implementations with [const error]
+
+pub trait ConstGenericTrait<const N: u32> {}
+
+impl ConstGenericTrait<{my_fn(1)}> for () {}
+
+impl ConstGenericTrait<{my_fn(2)}> for () {}
+
+const fn my_fn(v: u32) -> u32 {
+    panic!("Some error occurred"); //~ ERROR E0080
+    //~| ERROR E0080
+}
+
+fn main() {}

tests/ui/coherence/const-errs-dont-conflict-103369.stderr

@@ -0,0 +1,39 @@
+error[E0080]: evaluation of constant value failed
+  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+LL |     panic!("Some error occurred");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Some error occurred', $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+note: inside `my_fn`
+  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+LL |     panic!("Some error occurred");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: inside `<() as ConstGenericTrait<{my_fn(1)}>>::{constant#0}`
+  --> $DIR/const-errs-dont-conflict-103369.rs:5:25
+   |
+LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
+   |                         ^^^^^^^^
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0080]: evaluation of constant value failed
+  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+LL |     panic!("Some error occurred");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'Some error occurred', $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+note: inside `my_fn`
+  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
+   |
+LL |     panic!("Some error occurred");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+note: inside `<() as ConstGenericTrait<{my_fn(2)}>>::{constant#0}`
+  --> $DIR/const-errs-dont-conflict-103369.rs:7:25
+   |
+LL | impl ConstGenericTrait<{my_fn(2)}> for () {}
+   |                         ^^^^^^^^
+   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0080`.