From fe8d5b1635c048caf4d85813b770dd1d9fe938c8 Mon Sep 17 00:00:00 2001
From: Arthur Cohen <arthur.cohen@embecosm.com>
Date: Fri, 29 Aug 2025 15:35:33 +0200
Subject: [PATCH] nr2.0: Add extra check when resolving identifier patterns

gcc/rust/ChangeLog:

	* resolve/rust-late-name-resolver-2.0.cc (Late::visit): Check if an identifier pattern
	can be resolved in the types namespace before visiting it as an identifier proper.

gcc/testsuite/ChangeLog:

	* rust/compile/issue-4116.rs: New test.
---
 gcc/rust/resolve/rust-late-name-resolver-2.0.cc | 10 ++++++++++
 gcc/testsuite/rust/compile/issue-4116.rs        | 16 ++++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 gcc/testsuite/rust/compile/issue-4116.rs

diff --git a/gcc/rust/resolve/rust-late-name-resolver-2.0.cc b/gcc/rust/resolve/rust-late-name-resolver-2.0.cc
index 6effb7af42f1..9915d89b4679 100644
--- a/gcc/rust/resolve/rust-late-name-resolver-2.0.cc
+++ b/gcc/rust/resolve/rust-late-name-resolver-2.0.cc
@@ -206,6 +206,16 @@ Late::visit (AST::IdentifierPattern &identifier)
 {
   DefaultResolver::visit (identifier);
 
+  // We need to check if the Identifier resolves to a variant or empty struct
+  auto path = AST::SimplePath (identifier.get_ident ());
+
+  if (auto resolved = ctx.resolve_path (path, Namespace::Types))
+    {
+      ctx.map_usage (Usage (identifier.get_node_id ()),
+		     Definition (resolved->get_node_id ()));
+      return;
+    }
+
   visit_identifier_as_pattern (ctx, identifier.get_ident (),
 			       identifier.get_locus (),
 			       identifier.get_node_id (),
diff --git a/gcc/testsuite/rust/compile/issue-4116.rs b/gcc/testsuite/rust/compile/issue-4116.rs
new file mode 100644
index 000000000000..52b34b575acd
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-4116.rs
@@ -0,0 +1,16 @@
+enum Foo {
+    Relaxed,
+    SeqCst,
+    StressedOut,
+}
+
+use Foo::{Relaxed, SeqCst, StressedOut};
+
+fn main() {
+    let a = (Relaxed, Relaxed);
+
+    match a {
+        (Relaxed, Relaxed) => {}
+        _ => {}
+    }
+}