From 16bfe1e89f6bc6c9cf5c584247856840f83fad62 Mon Sep 17 00:00:00 2001
From: erichkeane <ekeane@nvidia.com>
Date: Wed, 24 Jan 2024 12:07:22 -0800
Subject: [PATCH] Fix comparison of Structural Values

Fixes a regression from #78041 as reported in the review.  The original
patch failed to compare the canonical type, which this adds.  A slightly
modified test of the original report is added.

(cherry picked from commit e3ee3762304aa81e4a240500844bfdd003401b36)
---
 clang/lib/AST/TemplateBase.cpp                 |  3 ++-
 .../SemaTemplate/temp_arg_nontype_cxx20.cpp    | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/clang/lib/AST/TemplateBase.cpp b/clang/lib/AST/TemplateBase.cpp
index 2bdbeb08ef20..3310d7dc24c5 100644
--- a/clang/lib/AST/TemplateBase.cpp
+++ b/clang/lib/AST/TemplateBase.cpp
@@ -450,7 +450,8 @@ bool TemplateArgument::structurallyEquals(const TemplateArgument &Other) const {
            getAsIntegral() == Other.getAsIntegral();
 
   case StructuralValue: {
-    if (getStructuralValueType() != Other.getStructuralValueType())
+    if (getStructuralValueType().getCanonicalType() !=
+        Other.getStructuralValueType().getCanonicalType())
       return false;
 
     llvm::FoldingSetNodeID A, B;
diff --git a/clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp b/clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp
index b5b8cadc909c..834174cdf6a3 100644
--- a/clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp
+++ b/clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp
@@ -336,3 +336,21 @@ template<int ...Ns> void bar(B b) {
   (b.operator Tbar<Ns>(), ...);
 }
 }
+
+namespace ReportedRegression1 {
+  const char kt[] = "dummy";
+
+  template <class T, const char id[]>
+    class SomeTempl { };
+
+  template <const char id[]>
+    class SomeTempl<int, id> {
+      public:
+        int exit_code() const { return 0; }
+    };
+
+  int use() {
+    SomeTempl<int, kt> dummy;
+    return dummy.exit_code();
+  }
+}