Rollup merge of rust-lang#35555 - circuitfox:E0128-update-error-forma…

…t, r=jonathandturner

E0128 update error format

Fixes rust-lang#35508

Part of rust-lang#35233

r? @jonathandturner

src/librustc_typeck/collect.rs

@@ -1903,9 +1903,12 @@ fn convert_default_type_parameter<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>,
  for leaf_ty in ty.walk() {
  if let ty::TyParam(p) = leaf_ty.sty {
  if p.space == space && p.idx >= index {
- span_err!(ccx.tcx.sess, path.span, E0128,
- "type parameters with a default cannot use \
- forward declared identifiers");
+ struct_span_err!(ccx.tcx.sess, path.span, E0128,
+ "type parameters with a default cannot use \
+ forward declared identifiers")
+ .span_label(path.span, &format!("defaulted type parameters \
+ cannot be forward declared"))
+ .emit();
 
  return ccx.tcx.types.err
  }

src/test/compile-fail/E0128.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 struct Foo<T=U, U=()> { //~ ERROR E0128
+ //~| NOTE defaulted type parameters cannot be forward declared
  field1: T,
  field2: U,
 }

src/test/compile-fail/issue-18183.rs

@@ -9,5 +9,6 @@
 // except according to those terms.
 
 pub struct Foo<Bar=Bar>; //~ ERROR E0128
+ //~| NOTE defaulted type parameters cannot be forward declared
 pub struct Baz(Foo);
 fn main() {}