Add runtime check to avoid overwrite arg easily in diag and store and restore snapshot when set subdiag arg

Signed-off-by: xizheyin <xizheyin@smail.nju.edu.cn>

2 files changed, 18 insertions, 6 deletions

diff --git a/compiler/rustc_mir_build/src/errors.rs b/compiler/rustc_mir_build/src/errors.rs
index ae09db50235..23869878e06 100644
--- a/compiler/rustc_mir_build/src/errors.rs
+++ b/compiler/rustc_mir_build/src/errors.rs
@@ -994,14 +994,15 @@ pub(crate) struct PatternNotCovered<'s, 'tcx> {
     pub(crate) uncovered: Uncovered,
     #[subdiagnostic]
     pub(crate) inform: Option<Inform>,
-    #[label(mir_build_confused)]
-    pub(crate) interpreted_as_const: Option<Span>,
     #[subdiagnostic]
-    pub(crate) interpreted_as_const_sugg: Option<InterpretedAsConst>,
+    pub(crate) interpreted_as_const: Option<InterpretedAsConst>,
+    #[subdiagnostic]
+    pub(crate) interpreted_as_const_sugg: Option<InterpretedAsConstSugg>,
     #[subdiagnostic]
     pub(crate) adt_defined_here: Option<AdtDefinedHere<'tcx>>,
     #[note(mir_build_privately_uninhabited)]
     pub(crate) witness_1_is_privately_uninhabited: bool,
+    pub(crate) witness_1: String,
     #[note(mir_build_pattern_ty)]
     pub(crate) _p: (),
     pub(crate) pattern_ty: Ty<'tcx>,
@@ -1016,6 +1017,14 @@ pub(crate) struct PatternNotCovered<'s, 'tcx> {
 #[note(mir_build_more_information)]
 pub(crate) struct Inform;
 
+#[derive(Subdiagnostic)]
+#[label(mir_build_confused)]
+pub(crate) struct InterpretedAsConst {
+    #[primary_span]
+    pub(crate) span: Span,
+    pub(crate) variable: String,
+}
+
 pub(crate) struct AdtDefinedHere<'tcx> {
     pub(crate) adt_def_span: Span,
     pub(crate) ty: Ty<'tcx>,
@@ -1046,7 +1055,7 @@ impl<'tcx> Subdiagnostic for AdtDefinedHere<'tcx> {
     applicability = "maybe-incorrect",
     style = "verbose"
 )]
-pub(crate) struct InterpretedAsConst {
+pub(crate) struct InterpretedAsConstSugg {
     #[primary_span]
     pub(crate) span: Span,
     pub(crate) variable: String,
diff --git a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
index 245bd866030..1b7866d79b7 100644
--- a/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
+++ b/compiler/rustc_mir_build/src/thir/pattern/check_match.rs
@@ -685,8 +685,8 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
             let span = self.tcx.def_span(def_id);
             let variable = self.tcx.item_name(def_id).to_string();
             // When we encounter a constant as the binding name, point at the `const` definition.
-            interpreted_as_const = Some(span);
-            interpreted_as_const_sugg = Some(InterpretedAsConst { span: pat.span, variable });
+            interpreted_as_const = Some(InterpretedAsConst { span, variable: variable.clone() });
+            interpreted_as_const_sugg = Some(InterpretedAsConstSugg { span: pat.span, variable });
         } else if let PatKind::Constant { .. } = unpeeled_pat.kind
             && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(pat.span)
         {
@@ -738,6 +738,8 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
             false
         };
 
+        let witness_1 = cx.print_witness_pat(witnesses.get(0).unwrap());
+
         self.error = Err(self.tcx.dcx().emit_err(PatternNotCovered {
             span: pat.span,
             origin,
@@ -746,6 +748,7 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
             interpreted_as_const,
             interpreted_as_const_sugg,
             witness_1_is_privately_uninhabited,
+            witness_1,
             _p: (),
             pattern_ty,
             let_suggestion,