infer: use derive more

Signed-off-by: David Wood <david.wood@huawei.com>

Author: davidtwco

compiler/rustc_error_messages/locales/en-US/infer.ftl

@@ -164,7 +164,9 @@ infer_region_explanation = {$pref_kind ->
 }
 
 infer_mismatched_static_lifetime = incompatible lifetime on type
-infer_msl_impl_note = ...does not necessarily outlive the static lifetime introduced by the compatible `impl`
+infer_does_not_outlive_static_from_impl = ...does not necessarily outlive the static lifetime introduced by the compatible `impl`
+infer_implicit_static_lifetime_note = this has an implicit `'static` lifetime requirement
+infer_implicit_static_lifetime_suggestion = consider relaxing the implicit `'static` requirement
 infer_msl_introduces_static = introduces a `'static` lifetime requirement
 infer_msl_unmet_req = because this has an unmet lifetime requirement
 infer_msl_trait_note = this has an implicit `'static` lifetime requirement

compiler/rustc_infer/src/errors/mod.rs

@@ -459,47 +459,34 @@ impl AddToDiagnostic for IntroducesStaticBecauseUnmetLifetimeReq {
     }
 }
 
-pub struct ImplNote {
-    pub impl_span: Option<Span>,
-}
-
-impl AddToDiagnostic for ImplNote {
-    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
-    where
-        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
-    {
-        match self.impl_span {
-            Some(span) => diag.span_note(span, fluent::infer::msl_impl_note),
-            None => diag.note(fluent::infer::msl_impl_note),
-        };
-    }
-}
-
-pub enum TraitSubdiag {
-    Note { span: Span },
-    Sugg { span: Span },
+// FIXME(#100717): replace with a `Option<Span>` when subdiagnostic supports that
+#[derive(Subdiagnostic)]
+pub enum DoesNotOutliveStaticFromImpl {
+    #[note(infer::does_not_outlive_static_from_impl)]
+    Spanned {
+        #[primary_span]
+        span: Span,
+    },
+    #[note(infer::does_not_outlive_static_from_impl)]
+    Unspanned,
 }
 
-// FIXME(#100717) used in `Vec<TraitSubdiag>` so requires eager translation/list support
-impl AddToDiagnostic for TraitSubdiag {
-    fn add_to_diagnostic_with<F>(self, diag: &mut Diagnostic, _: F)
-    where
-        F: Fn(&mut Diagnostic, SubdiagnosticMessage) -> SubdiagnosticMessage,
-    {
-        match self {
-            TraitSubdiag::Note { span } => {
-                diag.span_note(span, "this has an implicit `'static` lifetime requirement");
-            }
-            TraitSubdiag::Sugg { span } => {
-                diag.span_suggestion_verbose(
-                    span,
-                    "consider relaxing the implicit `'static` requirement",
-                    " + '_".to_owned(),
-                    rustc_errors::Applicability::MaybeIncorrect,
-                );
-            }
-        }
-    }
+#[derive(Subdiagnostic)]
+pub enum ImplicitStaticLifetimeSubdiag {
+    #[note(infer::implicit_static_lifetime_note)]
+    Note {
+        #[primary_span]
+        span: Span,
+    },
+    #[suggestion_verbose(
+        infer::implicit_static_lifetime_suggestion,
+        code = " + '_",
+        applicability = "maybe-incorrect"
+    )]
+    Sugg {
+        #[primary_span]
+        span: Span,
+    },
 }
 
 #[derive(Diagnostic)]
@@ -512,7 +499,7 @@ pub struct MismatchedStaticLifetime<'a> {
     #[subdiagnostic]
     pub expl: Option<note_and_explain::RegionExplanation<'a>>,
     #[subdiagnostic]
-    pub impl_note: ImplNote,
-    #[subdiagnostic]
-    pub trait_subdiags: Vec<TraitSubdiag>,
+    pub does_not_outlive_static_from_impl: DoesNotOutliveStaticFromImpl,
+    #[subdiagnostic(eager)]
+    pub implicit_static_lifetimes: Vec<ImplicitStaticLifetimeSubdiag>,
 }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mismatched_static_lifetime.rs

@@ -2,7 +2,9 @@
 //! to hold.
 
 use crate::errors::{note_and_explain, IntroducesStaticBecauseUnmetLifetimeReq};
-use crate::errors::{ImplNote, MismatchedStaticLifetime, TraitSubdiag};
+use crate::errors::{
+    DoesNotOutliveStaticFromImpl, ImplicitStaticLifetimeSubdiag, MismatchedStaticLifetime,
+};
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
 use crate::infer::{SubregionOrigin, TypeTrace};
@@ -56,7 +58,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             note_and_explain::SuffixKind::Continues,
         );
         let mut impl_span = None;
-        let mut trait_subdiags = Vec::new();
+        let mut implicit_static_lifetimes = Vec::new();
         if let Some(impl_node) = self.tcx().hir().get_if_local(*impl_def_id) {
             // If an impl is local, then maybe this isn't what they want. Try to
             // be as helpful as possible with implicit lifetimes.
@@ -90,10 +92,12 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
                 // Otherwise, point at all implicit static lifetimes
 
                 for span in &traits {
-                    trait_subdiags.push(TraitSubdiag::Note { span: *span });
+                    implicit_static_lifetimes
+                        .push(ImplicitStaticLifetimeSubdiag::Note { span: *span });
                     // It would be nice to put this immediately under the above note, but they get
                     // pushed to the end.
-                    trait_subdiags.push(TraitSubdiag::Sugg { span: span.shrink_to_hi() });
+                    implicit_static_lifetimes
+                        .push(ImplicitStaticLifetimeSubdiag::Sugg { span: span.shrink_to_hi() });
                 }
             }
         } else {
@@ -105,8 +109,10 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             cause_span: cause.span,
             unmet_lifetime_reqs: multispan_subdiag,
             expl,
-            impl_note: ImplNote { impl_span },
-            trait_subdiags,
+            does_not_outlive_static_from_impl: impl_span
+                .map(|span| DoesNotOutliveStaticFromImpl::Spanned { span })
+                .unwrap_or(DoesNotOutliveStaticFromImpl::Unspanned),
+            implicit_static_lifetimes,
         };
         let reported = self.tcx().sess.emit_err(err);
         Some(reported)

compiler/rustc_macros/src/diagnostics/subdiagnostic.rs

@@ -309,6 +309,8 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
                     report_error_if_not_applied_to_span(attr, &info)?;
 
                     let binding = info.binding.binding.clone();
+                    // FIXME(#100717): support `Option<Span>` on `primary_span` like in the
+                    // diagnostic derive
                     self.span_field.set_once(binding, span);
                 }