Rollup merge of #98267 - compiler-errors:suggest-wildcard-arm, r=oli-obk

Don't omit comma when suggesting wildcard arm after macro expr

* Also adds `Span::eq_ctxt` to consolidate the various usages of `span.ctxt() == other.ctxt()`
* Also fixes an unhygenic usage of spans which caused the suggestion to render weirdly when we had one arm match in a macro
* Also always suggests a comma (i.e. even after a block) if we're rendering a wildcard arm in a single-line match (looks prettier 🌹)

Fixes #94866

compiler/rustc_mir_transform/src/coverage/mod.rs

@@ -121,7 +121,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
 
         let source_file = source_map.lookup_source_file(body_span.lo());
         let fn_sig_span = match some_fn_sig.filter(|fn_sig| {
-            fn_sig.span.ctxt() == body_span.ctxt()
+            fn_sig.span.eq_ctxt(body_span)
                 && Lrc::ptr_eq(&source_file, &source_map.lookup_source_file(fn_sig.span.lo()))
         }) {
             Some(fn_sig) => fn_sig.span.with_hi(body_span.lo()),

compiler/rustc_mir_transform/src/coverage/spans.rs

@@ -195,7 +195,7 @@ impl CoverageSpan {
             .expn_span
             .parent_callsite()
             .unwrap_or_else(|| bug!("macro must have a parent"))
-            .ctxt() == body_span.ctxt()
+            .eq_ctxt(body_span)
         {
             return Some(current_macro);
         }