[clang] [Clang] prevent setting default lexical access specifier for missing primary declarations (PR #112424)

[Oleksandr T. via cfe-commits]

https://github.com/a-tarasyuk updated https://github.com/llvm/llvm-project/pull/112424

>From a22c6bae4f42f42e67f8e0c2b1f914e50d140099 Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Tue, 15 Oct 2024 22:43:24 +0300
Subject: [PATCH 1/2] [Clang] prevent setting default lexical access specifier
 for missing primary declarations

---
 clang/docs/ReleaseNotes.rst   | 2 ++
 clang/lib/Sema/SemaAccess.cpp | 3 ++-
 clang/test/SemaCXX/enum.cpp   | 8 ++++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 817e3abef8d566..64ffdcde045a3a 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -517,6 +517,8 @@ Bug Fixes to C++ Support
   certain situations. (#GH47400), (#GH90896)
 - Fix erroneous templated array size calculation leading to crashes in generated code. (#GH41441)
 - During the lookup for a base class name, non-type names are ignored. (#GH16855)
+- Fixed an assertion failure when the default lexical access specifier was set for missing
+  primary declarations. (#GH112208)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaAccess.cpp b/clang/lib/Sema/SemaAccess.cpp
index df6edb21a50dee..8b4a5b70669d84 100644
--- a/clang/lib/Sema/SemaAccess.cpp
+++ b/clang/lib/Sema/SemaAccess.cpp
@@ -39,7 +39,8 @@ bool Sema::SetMemberAccessSpecifier(NamedDecl *MemberDecl,
                                     AccessSpecifier LexicalAS) {
   if (!PrevMemberDecl) {
     // Use the lexical access specifier.
-    MemberDecl->setAccess(LexicalAS);
+    if (LexicalAS != AS_none)
+      MemberDecl->setAccess(LexicalAS);
     return false;
   }
 
diff --git a/clang/test/SemaCXX/enum.cpp b/clang/test/SemaCXX/enum.cpp
index 9c398cc8da886c..44042d8bf5cfc8 100644
--- a/clang/test/SemaCXX/enum.cpp
+++ b/clang/test/SemaCXX/enum.cpp
@@ -143,3 +143,11 @@ struct PR28903 {
     })
   };
 };
+
+namespace GH112208 {
+class C {
+  enum E { e = 0 };
+  void f(int, enum E;); // expected-error {{ISO C++ forbids forward references to 'enum' types}} \
+                        // expected-error {{unexpected ';' before ')'}}
+};
+}

>From 83ce02f2e0c7a4f5e8e774694240a9c2939bc2fa Mon Sep 17 00:00:00 2001
From: Oleksandr T <oleksandr.tarasiuk at outlook.com>
Date: Fri, 18 Oct 2024 14:55:47 +0300
Subject: [PATCH 2/2] prevent assertion failure by handling invalid enum
 forward declarations

---
 clang/docs/ReleaseNotes.rst   | 3 +--
 clang/lib/Sema/SemaAccess.cpp | 3 +--
 clang/lib/Sema/SemaDecl.cpp   | 2 ++
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 64ffdcde045a3a..3fd37663ca7bc6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -517,8 +517,7 @@ Bug Fixes to C++ Support
   certain situations. (#GH47400), (#GH90896)
 - Fix erroneous templated array size calculation leading to crashes in generated code. (#GH41441)
 - During the lookup for a base class name, non-type names are ignored. (#GH16855)
-- Fixed an assertion failure when the default lexical access specifier was set for missing
-  primary declarations. (#GH112208)
+- Fixed an assertion failure caused by invalid enum forward declarations. (#GH112208)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaAccess.cpp b/clang/lib/Sema/SemaAccess.cpp
index 8b4a5b70669d84..df6edb21a50dee 100644
--- a/clang/lib/Sema/SemaAccess.cpp
+++ b/clang/lib/Sema/SemaAccess.cpp
@@ -39,8 +39,7 @@ bool Sema::SetMemberAccessSpecifier(NamedDecl *MemberDecl,
                                     AccessSpecifier LexicalAS) {
   if (!PrevMemberDecl) {
     // Use the lexical access specifier.
-    if (LexicalAS != AS_none)
-      MemberDecl->setAccess(LexicalAS);
+    MemberDecl->setAccess(LexicalAS);
     return false;
   }
 
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index fece22c663d00c..9eb3d06289e88f 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -17942,6 +17942,8 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
             << Name;
         Invalid = true;
       }
+      if (TUK == TagUseKind::Declaration && Name)
+        Invalid = true;
     } else if (!PrevDecl) {
       Diag(Loc, diag::warn_decl_in_param_list) << Context.getTagDeclType(New);
     }