[clang] d812488 - Call MarkVirtualMembersReferenced on an actual class definition

[Stephan Bergmann via cfe-commits]

Author: Stephan Bergmann
Date: 2023-03-02T15:50:12+01:00
New Revision: d812488d3c54c07f24d4bef79e329f17e7f19c3b

URL: https://github.com/llvm/llvm-project/commit/d812488d3c54c07f24d4bef79e329f17e7f19c3b
DIFF: https://github.com/llvm/llvm-project/commit/d812488d3c54c07f24d4bef79e329f17e7f19c3b.diff

LOG: Call MarkVirtualMembersReferenced on an actual class definition

...rather than on potentially just a declaration.

Without the fix, the newly added clang/test/SemaCXX/warn-undefined-internal.cpp
failed with

> error: 'warning' diagnostics expected but not seen:
>   File /home/sbergman/github.com/llvm/llvm-project/clang/test/SemaCXX/warn-undefined-internal.cpp Line 12 (directive at /home/sbergman/github.com/llvm/llvm-project/clang/test/SemaCXX/warn-undefined-internal.cpp:13): function 'test2()::S::f' has internal linkage but is not defined
> error: 'note' diagnostics expected but not seen:
>   File /home/sbergman/github.com/llvm/llvm-project/clang/test/SemaCXX/warn-undefined-internal.cpp Line 14 (directive at /home/sbergman/github.com/llvm/llvm-project/clang/test/SemaCXX/warn-undefined-internal.cpp:15): used here

(I ran into this when two LibreOffice Clang plugins produced false positive
warnings, as they relied on Decl::isReferenced() returning true for such virtual
member functions of local classes.)

Differential Revision: https://reviews.llvm.org/D145123

Added: 
    clang/test/SemaCXX/warn-undefined-internal.cpp

Modified: 
    clang/docs/ReleaseNotes.rst
    clang/lib/Sema/SemaDeclCXX.cpp

Removed: 
    


################################################################################
diff  --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 7dc80a43e5eb..23a3bbd58b96 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -155,6 +155,8 @@ Improvements to Clang's diagnostics
 - Clang now warns by default for C++20 and later about deprecated capture of
   ``this`` with a capture default of ``=``. This warning can be disabled with
   ``-Wno-deprecated-this-capture``.
+- Clang had failed to emit some ``-Wundefined-internal`` for members of a local
+  class if that class was first introduced with a forward declaration.
 
 Bug Fixes in This Version
 -------------------------

diff  --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index ec85d503ccf8..cf74fcbc4cfa 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -17975,7 +17975,7 @@ void Sema::MarkVTableUsed(SourceLocation Loc, CXXRecordDecl *Class,
   // immediately. For all other classes, we mark their virtual members
   // at the end of the translation unit.
   if (Class->isLocalClass())
-    MarkVirtualMembersReferenced(Loc, Class);
+    MarkVirtualMembersReferenced(Loc, Class->getDefinition());
   else
     VTableUses.push_back(std::make_pair(Class, Loc));
 }

diff  --git a/clang/test/SemaCXX/warn-undefined-internal.cpp b/clang/test/SemaCXX/warn-undefined-internal.cpp
new file mode 100644
index 000000000000..81dbbba1d001
--- /dev/null
+++ b/clang/test/SemaCXX/warn-undefined-internal.cpp
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -Wundefined-internal -verify %s
+
+void test1() {
+  struct S { virtual void f(); };
+  // expected-warning at -1{{function 'test1()::S::f' has internal linkage but is not defined}}
+  S s;
+  // expected-note at -1{{used here}}
+}
+
+void test2() {
+  struct S;
+  struct S { virtual void f(); };
+  // expected-warning at -1{{function 'test2()::S::f' has internal linkage but is not defined}}
+  S s;
+  // expected-note at -1{{used here}}
+}