[clang] c57f034 - [clang][Sema] Add flag to LookupName to force C/ObjC codepath
Alex Langford via cfe-commits
cfe-commits at lists.llvm.org
Tue Apr 19 13:13:36 PDT 2022
Author: Alex Langford
Date: 2022-04-19T12:57:14-07:00
New Revision: c57f03415f9668f942802ff7108410d57c2b10da
URL: https://github.com/llvm/llvm-project/commit/c57f03415f9668f942802ff7108410d57c2b10da
DIFF: https://github.com/llvm/llvm-project/commit/c57f03415f9668f942802ff7108410d57c2b10da.diff
LOG: [clang][Sema] Add flag to LookupName to force C/ObjC codepath
Motivation: The intent here is for use in Swift.
When building a clang module for swift consumption, swift adds an
extension block to the module for name lookup purposes. Swift calls
this a SwiftLookupTable. One purpose that this serves is to handle
conflicting names between ObjC classes and ObjC protocols. They exist in
different namespaces in ObjC programs, but in Swift they would exist in
the same namespace. Swift handles this by appending a suffix to a
protocol name if it shares a name with a class. For example, if you have
an ObjC class named "Foo" and a protocol with the same name, the
protocol would be renamed to "FooProtocol" when imported into swift.
When constructing the previously mentioned SwiftLookupTable, we use
Sema::LookupName to look up name conflicts for the previous problem.
By this time, the Parser has long finished its job so the call to
LookupName gets nullptr for its Scope (TUScope will be nullptr
by this point). The C/ObjC path does not have this problem because it
only uses the Scope in specific scenarios. The C++ codepath uses the
Scope quite extensively and will fail early on if the Scope it gets is
null. In our very specific case of looking up ObjC classes with a
specific name, we want to force sema::LookupName to take the C/ObjC
codepath even if C++ or ObjC++ is enabled.
Added:
clang/unittests/Sema/SemaLookupTest.cpp
Modified:
clang/include/clang/Sema/Sema.h
clang/lib/Sema/SemaLookup.cpp
clang/unittests/Sema/CMakeLists.txt
Removed:
################################################################################
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index e2ae02ea9f76f..d5b73686e84a7 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -4252,8 +4252,8 @@ class Sema final {
= NotForRedeclaration);
bool LookupBuiltin(LookupResult &R);
void LookupNecessaryTypesForBuiltin(Scope *S, unsigned ID);
- bool LookupName(LookupResult &R, Scope *S,
- bool AllowBuiltinCreation = false);
+ bool LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation = false,
+ bool ForceNoCPlusPlus = false);
bool LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
bool InUnqualifiedLookup = false);
bool LookupQualifiedName(LookupResult &R, DeclContext *LookupCtx,
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 65f5112afee3e..ae3923854b527 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1931,13 +1931,14 @@ NamedDecl *LookupResult::getAcceptableDeclSlow(NamedDecl *D) const {
/// used to diagnose ambiguities.
///
/// @returns \c true if lookup succeeded and false otherwise.
-bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
+bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation,
+ bool ForceNoCPlusPlus) {
DeclarationName Name = R.getLookupName();
if (!Name) return false;
LookupNameKind NameKind = R.getLookupKind();
- if (!getLangOpts().CPlusPlus) {
+ if (!getLangOpts().CPlusPlus || ForceNoCPlusPlus) {
// Unqualified name lookup in C/Objective-C is purely lexical, so
// search in the declarations attached to the name.
if (NameKind == Sema::LookupRedeclarationWithLinkage) {
diff --git a/clang/unittests/Sema/CMakeLists.txt b/clang/unittests/Sema/CMakeLists.txt
index 194b7640b3c19..455c321d541b2 100644
--- a/clang/unittests/Sema/CMakeLists.txt
+++ b/clang/unittests/Sema/CMakeLists.txt
@@ -7,6 +7,7 @@ add_clang_unittest(SemaTests
ExternalSemaSourceTest.cpp
CodeCompleteTest.cpp
GslOwnerPointerInference.cpp
+ SemaLookupTest.cpp
)
clang_target_link_libraries(SemaTests
diff --git a/clang/unittests/Sema/SemaLookupTest.cpp b/clang/unittests/Sema/SemaLookupTest.cpp
new file mode 100644
index 0000000000000..d97b571f6a37c
--- /dev/null
+++ b/clang/unittests/Sema/SemaLookupTest.cpp
@@ -0,0 +1,60 @@
+#include "clang/AST/DeclarationName.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Parse/ParseAST.h"
+#include "clang/Sema/Lookup.h"
+#include "clang/Sema/Sema.h"
+#include "clang/Tooling/Tooling.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace clang;
+using namespace clang::tooling;
+
+namespace {
+
+class LookupAction : public ASTFrontendAction {
+ std::unique_ptr<ASTConsumer>
+ CreateASTConsumer(CompilerInstance &CI, StringRef /*Unused*/) override {
+ return std::make_unique<clang::ASTConsumer>();
+ }
+
+ void ExecuteAction() override {
+ CompilerInstance &CI = getCompilerInstance();
+ ASSERT_FALSE(CI.hasSema());
+ CI.createSema(getTranslationUnitKind(), nullptr);
+ ASSERT_TRUE(CI.hasSema());
+ Sema &S = CI.getSema();
+ ParseAST(S);
+
+ ASTContext &Ctx = S.getASTContext();
+ auto Name = &Ctx.Idents.get("Foo");
+ LookupResult R_cpp(S, Name, SourceLocation(), Sema::LookupOrdinaryName);
+ S.LookupName(R_cpp, S.TUScope, /*AllowBuiltinCreation=*/false,
+ /*ForceNoCPlusPlus=*/false);
+ // By this point, parsing is done and S.TUScope is nullptr
+ // CppLookupName will perform an early return with no results if the Scope
+ // we pass in is nullptr. We expect to find nothing.
+ ASSERT_TRUE(R_cpp.empty());
+
+ // On the other hand, the non-C++ path doesn't care if the Scope passed in
+ // is nullptr. We'll force the non-C++ path with a flag.
+ LookupResult R_nocpp(S, Name, SourceLocation(), Sema::LookupOrdinaryName);
+ S.LookupName(R_nocpp, S.TUScope, /*AllowBuiltinCreation=*/false,
+ /*ForceNoCPlusPlus=*/true);
+ ASSERT_TRUE(!R_nocpp.empty());
+ }
+};
+
+TEST(SemaLookupTest, ForceNoCPlusPlusPath) {
+ const char *file_contents = R"objcxx(
+ at protocol Foo
+ at end
+ at interface Foo <Foo>
+ at end
+ )objcxx";
+ ASSERT_TRUE(runToolOnCodeWithArgs(std::make_unique<LookupAction>(),
+ file_contents, {"-x", "objective-c++"},
+ "test.mm"));
+}
+} // namespace
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