don't trim paths in collector PME message

Author: lqd

compiler/rustc_mir/src/monomorphize/collector.rs

@@ -194,6 +194,7 @@ use rustc_middle::mir::mono::{InstantiationMode, MonoItem};
 use rustc_middle::mir::visit::Visitor as MirVisitor;
 use rustc_middle::mir::{self, Local, Location};
 use rustc_middle::ty::adjustment::{CustomCoerceUnsized, PointerCast};
+use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
 use rustc_middle::ty::{self, GenericParamDefKind, Instance, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::{middle::codegen_fn_attrs::CodegenFnAttrFlags, mir::visit::TyContext};
@@ -444,12 +445,10 @@ fn collect_items_rec<'tcx>(
     // defined in the local crate.
     if tcx.sess.diagnostic().err_count() > error_count && starting_point.node.krate() != LOCAL_CRATE
     {
+        let formatted_item = with_no_trimmed_paths(|| starting_point.node.to_string());
         tcx.sess.span_note_without_error(
             starting_point.span,
-            &format!(
-                "the above error was encountered while instantiating `{}`",
-                starting_point.node
-            ),
+            &format!("the above error was encountered while instantiating `{}`", formatted_item),
         );
     }
 

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>();