[clang][modules] Fix crash in enum visibility lookup for C++20 header units (#166272)
Fixes #165445.
Fixes a crash when `ASTWriter::GenerateNameLookupTable` processes enum
constants from C++20 header units.
The special handling for enum constants, introduced in fccc6ee, doesn't
account for declarations whose owning module is a C++20 header unit. It
calls `isNamedModule()` on the result of
`getTopLevelOwningNamedModule()`, which returns null for header units,
causing a null pointer dereference.
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 3ac338e..b1fd151 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4374,8 +4374,7 @@
// parent of parent. We DON'T remove the enum constant from its parent. So
// we don't need to care about merging problems here.
if (auto *ECD = dyn_cast<EnumConstantDecl>(D);
- ECD && DC.isFileContext() && ECD->getOwningModule() &&
- ECD->getTopLevelOwningNamedModule()->isNamedModule()) {
+ ECD && DC.isFileContext() && ECD->getTopLevelOwningNamedModule()) {
if (llvm::all_of(
DC.noload_lookup(
cast<EnumDecl>(ECD->getDeclContext())->getDeclName()),
diff --git a/clang/test/Modules/crash-enum-visibility-with-header-unit.cppm b/clang/test/Modules/crash-enum-visibility-with-header-unit.cppm
new file mode 100644
index 0000000..90c5779
--- /dev/null
+++ b/clang/test/Modules/crash-enum-visibility-with-header-unit.cppm
@@ -0,0 +1,46 @@
+// Fixes #165445
+
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 -x c++-user-header %t/header.h \
+// RUN: -emit-header-unit -o %t/header.pcm
+//
+// RUN: %clang_cc1 -std=c++20 %t/A.cppm -fmodule-file=%t/header.pcm \
+// RUN: -emit-module-interface -o %t/A.pcm
+//
+// RUN: %clang_cc1 -std=c++20 %t/B.cppm -fmodule-file=%t/header.pcm \
+// RUN: -emit-module-interface -o %t/B.pcm
+//
+// RUN: %clang_cc1 -std=c++20 %t/use.cpp \
+// RUN: -fmodule-file=A=%t/A.pcm -fmodule-file=B=%t/B.pcm \
+// RUN: -fmodule-file=%t/header.pcm \
+// RUN: -verify -fsyntax-only
+
+//--- enum.h
+enum E { Value };
+
+//--- header.h
+#include "enum.h"
+
+//--- A.cppm
+module;
+#include "enum.h"
+export module A;
+
+auto e = Value;
+
+//--- B.cppm
+export module B;
+import "header.h";
+
+auto e = Value;
+
+//--- use.cpp
+// expected-no-diagnostics
+import A;
+import B;
+#include "enum.h"
+
+auto e = Value;
