[C++20] [Modules] [Serialization] Check input file contents with option ForceCheckCXX20ModulesInputFiles enabled

With overriden input files, e,g,. the compiler get the file from an
in-memroy buffer, the compiler can't get correct modified time information
to indicate whehter the input files are changed or not. Then, the
semantics of ForceCheckCXX20ModulesInputFiles are broken.

In this patch, if both ForceCheckCXX20ModulesInputFiles and
ValidateASTInputFilesContent and enabled, the compiler will still check the
hash value of the contents even if their modification time is the same.

1 files changed, 144 insertions, 0 deletions

diff --git a/clang/unittests/Serialization/ForceCheckFileInputTest.cpp b/clang/unittests/Serialization/ForceCheckFileInputTest.cpp
new file mode 100644
index 0000000..c1f6d40
--- /dev/null
+++ b/clang/unittests/Serialization/ForceCheckFileInputTest.cpp
@@ -0,0 +1,144 @@
+//===- unittests/Serialization/ForceCheckFileInputTest.cpp - CI tests -----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/CompilerInvocation.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Frontend/Utils.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Serialization/ASTReader.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace clang;
+
+namespace {
+
+class ForceCheckFileInputTest : public ::testing::Test {
+  void SetUp() override {
+    EXPECT_FALSE(sys::fs::createUniqueDirectory("modules-test", TestDir));
+  }
+
+  void TearDown() override { sys::fs::remove_directories(TestDir); }
+
+public:
+  SmallString<256> TestDir;
+
+  void addFile(StringRef Path, StringRef Contents) {
+    EXPECT_FALSE(sys::path::is_absolute(Path));
+
+    SmallString<256> AbsPath(TestDir);
+    sys::path::append(AbsPath, Path);
+
+    EXPECT_FALSE(
+        sys::fs::create_directories(llvm::sys::path::parent_path(AbsPath)));
+
+    std::error_code EC;
+    llvm::raw_fd_ostream OS(AbsPath, EC);
+    EXPECT_FALSE(EC);
+    OS << Contents;
+  }
+};
+
+TEST_F(ForceCheckFileInputTest, ForceCheck) {
+  addFile("a.cppm", R"cpp(
+export module a;
+export int aa = 43;
+  )cpp");
+
+  std::string BMIPath = llvm::Twine(TestDir + "/a.pcm").str();
+
+  {
+    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+        CompilerInstance::createDiagnostics(new DiagnosticOptions());
+    CreateInvocationOptions CIOpts;
+    CIOpts.Diags = Diags;
+    CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+
+    const char *Args[] = {
+        "clang++",       "-std=c++20", "--precompile", "-working-directory",
+        TestDir.c_str(), "a.cppm",     "-o",           BMIPath.c_str()};
+    std::shared_ptr<CompilerInvocation> Invocation =
+        createInvocation(Args, CIOpts);
+    EXPECT_TRUE(Invocation);
+
+    auto Buf = CIOpts.VFS->getBufferForFile("a.cppm");
+    EXPECT_TRUE(Buf);
+
+    Invocation->getPreprocessorOpts().addRemappedFile("a.cppm", Buf->get());
+
+    Buf->release();
+
+    CompilerInstance Instance;
+    Instance.setDiagnostics(Diags.get());
+    Instance.setInvocation(Invocation);
+
+    if (auto VFSWithRemapping = createVFSFromCompilerInvocation(
+            Instance.getInvocation(), Instance.getDiagnostics(), CIOpts.VFS))
+      CIOpts.VFS = VFSWithRemapping;
+    Instance.createFileManager(CIOpts.VFS);
+
+    Instance.getHeaderSearchOpts().ValidateASTInputFilesContent = true;
+
+    GenerateModuleInterfaceAction Action;
+    EXPECT_TRUE(Instance.ExecuteAction(Action));
+    EXPECT_FALSE(Diags->hasErrorOccurred());
+  }
+
+  {
+    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+        CompilerInstance::createDiagnostics(new DiagnosticOptions());
+    CreateInvocationOptions CIOpts;
+    CIOpts.Diags = Diags;
+    CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+
+    std::string BMIPath = llvm::Twine(TestDir + "/a.pcm").str();
+    const char *Args[] = {
+        "clang++",       "-std=c++20", "--precompile", "-working-directory",
+        TestDir.c_str(), "a.cppm",     "-o",           BMIPath.c_str()};
+    std::shared_ptr<CompilerInvocation> Invocation =
+        createInvocation(Args, CIOpts);
+    EXPECT_TRUE(Invocation);
+
+    CompilerInstance Clang;
+
+    Clang.setInvocation(Invocation);
+    Clang.setDiagnostics(Diags.get());
+    FileManager *FM = Clang.createFileManager(CIOpts.VFS);
+    Clang.createSourceManager(*FM);
+
+    EXPECT_TRUE(Clang.createTarget());
+    Clang.createPreprocessor(TU_Complete);
+    Clang.getHeaderSearchOpts().ForceCheckCXX20ModulesInputFiles = true;
+    Clang.getHeaderSearchOpts().ValidateASTInputFilesContent = true;
+    Clang.createASTReader();
+
+    addFile("a.cppm", R"cpp(
+export module a;
+export int aa = 44;
+  )cpp");
+
+    auto ReadResult =
+        Clang.getASTReader()->ReadAST(BMIPath, serialization::MK_MainFile,
+                                      SourceLocation(), ASTReader::ARR_None);
+
+    // We shall be able to detect the content change here.
+    EXPECT_NE(ReadResult, ASTReader::Success);
+  }
+}
+
+} // anonymous namespace