review comments

- Remove check for "how many path segments is the pattern"
- Check before suggesting if the path has multiple path segments

Author: estebank

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -677,6 +677,9 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
             ..
         } = pat.kind
             && let DefKind::Const = self.tcx.def_kind(def_id)
+            && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(pat.span)
+            // We filter out paths with multiple path::segments.
+            && snippet.chars().all(|c| c.is_alphanumeric() || c == '_')
         {
             let span = self.tcx.def_span(def_id);
             let variable = self.tcx.item_name(def_id).to_string();
@@ -1143,7 +1146,11 @@ fn report_non_exhaustive_match<'p, 'tcx>(
 
     for &arm in arms {
         let arm = &thir.arms[arm];
-        if let PatKind::ExpandedConstant { def_id, is_inline: false, .. } = arm.pattern.kind {
+        if let PatKind::ExpandedConstant { def_id, is_inline: false, .. } = arm.pattern.kind
+            && let Ok(snippet) = cx.tcx.sess.source_map().span_to_snippet(arm.pattern.span)
+            // We filter out paths with multiple path::segments.
+            && snippet.chars().all(|c| c.is_alphanumeric() || c == '_')
+        {
             let const_name = cx.tcx.item_name(def_id);
             err.span_label(
                 arm.pattern.span,

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -160,13 +160,19 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                     }
                     kind => (kind, None, None),
                 };
-                let value = if let PatKind::Constant { value } = kind {
-                    value
-                } else {
-                    let msg = format!(
-                        "found bad range pattern endpoint `{expr:?}` outside of error recovery"
-                    );
-                    return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
+                let value = match kind {
+                    PatKind::Constant { value } => value,
+                    PatKind::ExpandedConstant { subpattern, .. }
+                        if let PatKind::Constant { value } = subpattern.kind =>
+                    {
+                        value
+                    }
+                    _ => {
+                        let msg = format!(
+                            "found bad range pattern endpoint `{expr:?}` outside of error recovery"
+                        );
+                        return Err(self.tcx.dcx().span_delayed_bug(expr.span, msg));
+                    }
                 };
                 Ok((Some(PatRangeBoundary::Finite(value)), ascr, inline_const))
             }
@@ -570,19 +576,13 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         let args = self.typeck_results.node_args(id);
         let c = ty::Const::new_unevaluated(self.tcx, ty::UnevaluatedConst { def: def_id, args });
         let subpattern = self.const_to_pat(c, ty, id, span);
-        let pattern = if let hir::QPath::Resolved(None, path) = qpath
-            && path.segments.len() == 1
-        {
-            // We only want to mark constants when referenced as bare names that could have been
-            // new bindings if the `const` didn't exist.
-            Box::new(Pat {
-                span,
-                ty,
-                kind: PatKind::ExpandedConstant { subpattern, def_id, is_inline: false },
-            })
-        } else {
-            subpattern
-        };
+        // We only want to mark constants when referenced as bare names that could have been
+        // new bindings if the `const` didn't exist.
+        let pattern = Box::new(Pat {
+            span,
+            ty,
+            kind: PatKind::ExpandedConstant { subpattern, def_id, is_inline: false },
+        });
 
         if !is_associated_const {
             return pattern;