[clang] [Clang][Sema] fix outline member function template with default align crash (PR #78400)

[Qizhi Hu via cfe-commits]

https://github.com/jcsxky updated https://github.com/llvm/llvm-project/pull/78400

>From e8a5715a6255bc110823dbe36734bb7bd17753d5 Mon Sep 17 00:00:00 2001
From: huqizhi <huqizhi at feysh.com>
Date: Wed, 17 Jan 2024 14:16:34 +0800
Subject: [PATCH] [Clang][Sema] fix outline member function template with
 default align crash

---
 clang/lib/Sema/SemaTemplateInstantiate.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index fc80515b45e35b4..1ed63db75294aab 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -3051,6 +3051,7 @@ bool Sema::SubstDefaultArgument(
     //   default argument expression appears.
     ContextRAII SavedContext(*this, FD);
     std::unique_ptr<LocalInstantiationScope> LIS;
+    auto NewTemplateArgs = TemplateArgs;
 
     if (ForCallExpr) {
       // When instantiating a default argument due to use in a call expression,
@@ -3063,11 +3064,18 @@ bool Sema::SubstDefaultArgument(
           /*ForDefinition*/ false);
       if (addInstantiatedParametersToScope(FD, PatternFD, *LIS, TemplateArgs))
         return true;
+      if (FD->isOutOfLine()) {
+        auto *CurrentTemplateArgumentList = TemplateArgumentList::CreateCopy(
+            getASTContext(), TemplateArgs.getInnermost());
+        NewTemplateArgs = getTemplateInstantiationArgs(
+            FD, FD->getDeclContext(), true, CurrentTemplateArgumentList, true,
+            nullptr, false, false);
+      }
     }
 
     runWithSufficientStackSpace(Loc, [&] {
-      Result = SubstInitializer(PatternExpr, TemplateArgs,
-                                /*DirectInit*/false);
+      Result = SubstInitializer(PatternExpr, NewTemplateArgs,
+                                /*DirectInit*/ false);
     });
   }
   if (Result.isInvalid())