[clang] [Clang][Sema] Fix a bug on type constraint checking (PR #84671)

[Qizhi Hu via cfe-commits]

https://github.com/jcsxky updated https://github.com/llvm/llvm-project/pull/84671

>From 849db0cede4d0fe108ec7cf530974606a426b9db Mon Sep 17 00:00:00 2001
From: huqizhi <huqizhi at feysh.com>
Date: Sun, 10 Mar 2024 16:11:18 +0800
Subject: [PATCH] [Clang][Sema] Fix a bug on type constraint checking

---
 clang/docs/ReleaseNotes.rst                    |  2 ++
 clang/lib/Sema/SemaTemplateInstantiateDecl.cpp |  1 +
 clang/test/Sema/PR84368.cpp                    | 16 ++++++++++++++++
 3 files changed, 19 insertions(+)
 create mode 100644 clang/test/Sema/PR84368.cpp

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5fe3fd066df235..cede0deb179d5c 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -376,6 +376,8 @@ Bug Fixes to C++ Support
 - Fixed a crash in constant evaluation when trying to access a
   captured ``this`` pointer in a lambda with an explicit object parameter.
   Fixes (#GH80997)
+- Fix an issue where missing set friend declaration in template class instantiation.
+  Fixes (#GH84368).
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 8ef8bfdf2a7b56..dc972018e7b281 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1727,6 +1727,7 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
     assert(!Owner->isDependentContext());
     Inst->setLexicalDeclContext(Owner);
     RecordInst->setLexicalDeclContext(Owner);
+    Inst->setObjectOfFriendDecl();
 
     if (PrevClassTemplate) {
       Inst->setCommonPtr(PrevClassTemplate->getCommonPtr());
diff --git a/clang/test/Sema/PR84368.cpp b/clang/test/Sema/PR84368.cpp
new file mode 100644
index 00000000000000..6551df29358920
--- /dev/null
+++ b/clang/test/Sema/PR84368.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -std=c++20 -verify %s
+// RUN: %clang_cc1 -std=c++23 -verify %s
+// expected-no-diagnostics
+
+template<class T> concept IsOk = requires() { typename T::Float; };
+
+template<IsOk T> struct Thing;
+
+template<IsOk T> struct Foobar {
+  template<int> struct Inner {
+    template<IsOk T2> friend struct Thing;
+  };
+};
+
+struct MyType { using Float=float; };
+Foobar<MyType>::Inner<0> foobar;