Auto merge of #124295 - fmease:rollup-i3apkc6, r=fmease

Rollup of 7 pull requests

Successful merges:

 - #120929 (Wrap dyn type with parentheses in suggestion)
 - #122591 (Suggest using type args directly instead of equality constraint)
 - #122598 (deref patterns: lower deref patterns to MIR)
 - #123048 (alloc::Layout: explicitly document size invariant on the type level)
 - #123993 (Do `check_coroutine_obligations` once per typeck root)
 - #124218 (Allow nesting subdiagnostics in #[derive(Subdiagnostic)])
 - #124285 (Mark ``@RUSTC_BUILTIN`` search path usage as unstable)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 15 insertions, 18 deletions

diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index e3363e89594..b3c1c6c8515 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -40,8 +40,8 @@ pub use diagnostic::{
     SubdiagMessageOp, Subdiagnostic,
 };
 pub use diagnostic_impls::{
-    DiagArgFromDisplay, DiagSymbolList, ExpectedLifetimeParameter, IndicateAnonymousLifetime,
-    SingleLabelManySpans,
+    DiagArgFromDisplay, DiagSymbolList, ElidedLifetimeInPathSubdiag, ExpectedLifetimeParameter,
+    IndicateAnonymousLifetime, SingleLabelManySpans,
 };
 pub use emitter::ColorConfig;
 pub use rustc_error_messages::{
@@ -1911,27 +1911,24 @@ impl Level {
 }
 
 // FIXME(eddyb) this doesn't belong here AFAICT, should be moved to callsite.
-pub fn add_elided_lifetime_in_path_suggestion<G: EmissionGuarantee>(
+pub fn elided_lifetime_in_path_suggestion(
     source_map: &SourceMap,
-    diag: &mut Diag<'_, G>,
     n: usize,
     path_span: Span,
     incl_angl_brckt: bool,
     insertion_span: Span,
-) {
-    diag.subdiagnostic(diag.dcx, ExpectedLifetimeParameter { span: path_span, count: n });
-    if !source_map.is_span_accessible(insertion_span) {
-        // Do not try to suggest anything if generated by a proc-macro.
-        return;
-    }
-    let anon_lts = vec!["'_"; n].join(", ");
-    let suggestion =
-        if incl_angl_brckt { format!("<{anon_lts}>") } else { format!("{anon_lts}, ") };
-
-    diag.subdiagnostic(
-        diag.dcx,
-        IndicateAnonymousLifetime { span: insertion_span.shrink_to_hi(), count: n, suggestion },
-    );
+) -> ElidedLifetimeInPathSubdiag {
+    let expected = ExpectedLifetimeParameter { span: path_span, count: n };
+    // Do not try to suggest anything if generated by a proc-macro.
+    let indicate = source_map.is_span_accessible(insertion_span).then(|| {
+        let anon_lts = vec!["'_"; n].join(", ");
+        let suggestion =
+            if incl_angl_brckt { format!("<{anon_lts}>") } else { format!("{anon_lts}, ") };
+
+        IndicateAnonymousLifetime { span: insertion_span.shrink_to_hi(), count: n, suggestion }
+    });
+
+    ElidedLifetimeInPathSubdiag { expected, indicate }
 }
 
 pub fn report_ambiguity_error<'a, G: EmissionGuarantee>(