[clang] [Clang] Fix canonicalization of pack indexing types (PR #123209)

[via cfe-commits]

https://github.com/cor3ntin created https://github.com/llvm/llvm-project/pull/123209

A canonicalized pack indexing should refer to a canonicalized pattern

Fixes #123033

>From 6b533adf454e59db7a4afec8b91e1770875be588 Mon Sep 17 00:00:00 2001
From: Corentin Jabot <corentinjabot at gmail.com>
Date: Thu, 16 Jan 2025 15:33:01 +0100
Subject: [PATCH] [Clang] Fix canonicalization of pack indexing types

A canonicalized pack indexing should refer to a canonicalized
pattern

Fixes #123033
---
 clang/docs/ReleaseNotes.rst                |  2 ++
 clang/lib/AST/ASTContext.cpp               |  8 +++++---
 clang/test/SemaCXX/cxx2c-pack-indexing.cpp | 23 ++++++++++++++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f6be841035db18..14fe920985d6a9 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -952,6 +952,8 @@ Bug Fixes to C++ Support
 - Fixed a crash when __PRETTY_FUNCTION__ or __FUNCSIG__ (clang-cl) appears in the trailing return type of the lambda (#GH121274)
 - Fixed a crash caused by the incorrect construction of template arguments for CTAD alias guides when type
   constraints are applied. (#GH122134)
+- Fixed canonicalization of pack indexing types - Clang did not always recognized identical pack indexing. (#GH123033)
+
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index be1dd29d462788..d0ce4c511aedd0 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -6248,7 +6248,8 @@ QualType ASTContext::getPackIndexingType(QualType Pattern, Expr *IndexExpr,
     Canonical = getCanonicalType(Expansions[Index]);
   } else {
     llvm::FoldingSetNodeID ID;
-    PackIndexingType::Profile(ID, *this, Pattern, IndexExpr, FullySubstituted);
+    PackIndexingType::Profile(ID, *this, Pattern.getCanonicalType(), IndexExpr,
+                              FullySubstituted);
     void *InsertPos = nullptr;
     PackIndexingType *Canon =
         DependentPackIndexingTypes.FindNodeOrInsertPos(ID, InsertPos);
@@ -6256,8 +6257,9 @@ QualType ASTContext::getPackIndexingType(QualType Pattern, Expr *IndexExpr,
       void *Mem = Allocate(
           PackIndexingType::totalSizeToAlloc<QualType>(Expansions.size()),
           TypeAlignment);
-      Canon = new (Mem) PackIndexingType(*this, QualType(), Pattern, IndexExpr,
-                                         FullySubstituted, Expansions);
+      Canon = new (Mem)
+          PackIndexingType(*this, QualType(), Pattern.getCanonicalType(),
+                           IndexExpr, FullySubstituted, Expansions);
       DependentPackIndexingTypes.InsertNode(Canon, InsertPos);
     }
     Canonical = QualType(Canon, 0);
diff --git a/clang/test/SemaCXX/cxx2c-pack-indexing.cpp b/clang/test/SemaCXX/cxx2c-pack-indexing.cpp
index 58b642d2735b6e..202a819655217b 100644
--- a/clang/test/SemaCXX/cxx2c-pack-indexing.cpp
+++ b/clang/test/SemaCXX/cxx2c-pack-indexing.cpp
@@ -321,3 +321,26 @@ namespace GH121242 {
         (void)z<X{}>;
     }
 } // namespace GH121242
+
+namespace GH123033 {
+  template <class... Types>
+  requires __is_same_as(Types...[0], int)
+  void print(double d);
+
+  template <class... Types>
+  requires  __is_same_as(Types...[0], int)
+  void print(double d);
+
+  template <class... Types>
+  Types...[0] convert(double d);
+
+  template <class... Types>
+  Types...[0] convert(double d) {
+      return static_cast<Types...[0]>(d);
+  }
+
+  void f() {
+      print<int, int>(12.34);
+      convert<int, int>(12.34);
+  }
+}