[clang][frontend] Require invocation to construct `CompilerInstance` (#137668)

This PR makes it so that `CompilerInvocation` needs to be provided to
`CompilerInstance` on construction. There are a couple of benefits in my
view:
* Making it impossible to mis-use some `CompilerInstance` APIs. For
example there are cases, where `createDiagnostics()` was called before
`setInvocation()`, causing the `DiagnosticEngine` to use the
default-constructed `DiagnosticOptions` instead of the intended ones.
* This shrinks `CompilerInstance`'s state space.
* This makes it possible to access **the** invocation in
`CompilerInstance`'s constructor (to be used in a follow-up).

4 files changed, 13 insertions, 26 deletions

diff --git a/clang/unittests/Frontend/CodeGenActionTest.cpp b/clang/unittests/Frontend/CodeGenActionTest.cpp
index d855302..90818b7 100644
--- a/clang/unittests/Frontend/CodeGenActionTest.cpp
+++ b/clang/unittests/Frontend/CodeGenActionTest.cpp
@@ -51,8 +51,7 @@ TEST(CodeGenTest, TestNullCodeGen) {
       FrontendInputFile("test.cc", Language::CXX));
   Invocation->getFrontendOpts().ProgramAction = EmitLLVM;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
-  Compiler.setInvocation(std::move(Invocation));
+  CompilerInstance Compiler(std::move(Invocation));
   Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
   EXPECT_TRUE(Compiler.hasDiagnostics());
 
@@ -69,8 +68,7 @@ TEST(CodeGenTest, CodeGenFromIRMemBuffer) {
       FrontendInputFile(*MemBuffer, Language::LLVM_IR));
   Invocation->getFrontendOpts().ProgramAction = frontend::EmitLLVMOnly;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
-  Compiler.setInvocation(std::move(Invocation));
+  CompilerInstance Compiler(std::move(Invocation));
   Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
   EXPECT_TRUE(Compiler.hasDiagnostics());
 
@@ -97,11 +95,10 @@ TEST(CodeGenTest, DebugInfoCWDCodeGen) {
   Invocation->getFrontendOpts().ProgramAction = EmitLLVM;
   Invocation->getTargetOpts().Triple = "x86_64-unknown-linux-gnu";
   Invocation->getCodeGenOpts().setDebugInfo(codegenoptions::FullDebugInfo);
-  CompilerInstance Compiler;
+  CompilerInstance Compiler(std::move(Invocation));
 
   SmallString<256> IRBuffer;
   Compiler.setOutputStream(std::make_unique<raw_svector_ostream>(IRBuffer));
-  Compiler.setInvocation(std::move(Invocation));
   Compiler.createDiagnostics(*VFS);
   Compiler.createFileManager(std::move(VFS));
 
diff --git a/clang/unittests/Frontend/CompilerInstanceTest.cpp b/clang/unittests/Frontend/CompilerInstanceTest.cpp
index 07329eb2..6e9a6f5 100644
--- a/clang/unittests/Frontend/CompilerInstanceTest.cpp
+++ b/clang/unittests/Frontend/CompilerInstanceTest.cpp
@@ -66,9 +66,8 @@ TEST(CompilerInstance, DefaultVFSOverlayFromInvocation) {
     FAIL() << "could not create compiler invocation";
   // Create a minimal CompilerInstance which should use the VFS we specified
   // in the CompilerInvocation (as we don't explicitly set our own).
-  CompilerInstance Instance;
+  CompilerInstance Instance(std::move(CInvok));
   Instance.setDiagnostics(Diags.get());
-  Instance.setInvocation(CInvok);
   Instance.createFileManager();
 
   // Check if the virtual file exists which means that our VFS is used by the
diff --git a/clang/unittests/Frontend/FrontendActionTest.cpp b/clang/unittests/Frontend/FrontendActionTest.cpp
index a6bb767..4e04078 100644
--- a/clang/unittests/Frontend/FrontendActionTest.cpp
+++ b/clang/unittests/Frontend/FrontendActionTest.cpp
@@ -90,8 +90,7 @@ TEST(ASTFrontendAction, Sanity) {
       FrontendInputFile("test.cc", Language::CXX));
   invocation->getFrontendOpts().ProgramAction = frontend::ParseSyntaxOnly;
   invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance compiler;
-  compiler.setInvocation(std::move(invocation));
+  CompilerInstance compiler(std::move(invocation));
   compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
   TestASTFrontendAction test_action;
@@ -110,8 +109,7 @@ TEST(ASTFrontendAction, IncrementalParsing) {
       FrontendInputFile("test.cc", Language::CXX));
   invocation->getFrontendOpts().ProgramAction = frontend::ParseSyntaxOnly;
   invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance compiler;
-  compiler.setInvocation(std::move(invocation));
+  CompilerInstance compiler(std::move(invocation));
   compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
   TestASTFrontendAction test_action(/*enableIncrementalProcessing=*/true);
@@ -137,8 +135,7 @@ TEST(ASTFrontendAction, LateTemplateIncrementalParsing) {
       FrontendInputFile("test.cc", Language::CXX));
   invocation->getFrontendOpts().ProgramAction = frontend::ParseSyntaxOnly;
   invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance compiler;
-  compiler.setInvocation(std::move(invocation));
+  CompilerInstance compiler(std::move(invocation));
   compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
   TestASTFrontendAction test_action(/*enableIncrementalProcessing=*/true,
@@ -183,8 +180,7 @@ TEST(PreprocessorFrontendAction, EndSourceFile) {
       FrontendInputFile("test.cc", Language::CXX));
   Invocation->getFrontendOpts().ProgramAction = frontend::ParseSyntaxOnly;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
-  Compiler.setInvocation(std::move(Invocation));
+  CompilerInstance Compiler(std::move(Invocation));
   Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
   TestPPCallbacks *Callbacks = new TestPPCallbacks;
@@ -244,8 +240,7 @@ TEST(ASTFrontendAction, ExternalSemaSource) {
       FrontendInputFile("test.cc", Language::CXX));
   Invocation->getFrontendOpts().ProgramAction = frontend::ParseSyntaxOnly;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
-  Compiler.setInvocation(std::move(Invocation));
+  CompilerInstance Compiler(std::move(Invocation));
   auto *TDC = new TypoDiagnosticConsumer;
   Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem(), TDC,
                              /*ShouldOwnClient=*/true);
@@ -278,8 +273,7 @@ TEST(GeneratePCHFrontendAction, CacheGeneratedPCH) {
     Invocation->getFrontendOpts().OutputFile = PCHFilename.str().str();
     Invocation->getFrontendOpts().ProgramAction = frontend::GeneratePCH;
     Invocation->getTargetOpts().Triple = "x86_64-apple-darwin19.0.0";
-    CompilerInstance Compiler;
-    Compiler.setInvocation(std::move(Invocation));
+    CompilerInstance Compiler(std::move(Invocation));
     Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
     GeneratePCHAction TestAction;
diff --git a/clang/unittests/Frontend/OutputStreamTest.cpp b/clang/unittests/Frontend/OutputStreamTest.cpp
index 27d2d7f..0eda3a1 100644
--- a/clang/unittests/Frontend/OutputStreamTest.cpp
+++ b/clang/unittests/Frontend/OutputStreamTest.cpp
@@ -31,14 +31,13 @@ TEST(FrontendOutputTests, TestOutputStream) {
       FrontendInputFile("test.cc", Language::CXX));
   Invocation->getFrontendOpts().ProgramAction = EmitBC;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
+  CompilerInstance Compiler(std::move(Invocation));
 
   SmallVector<char, 256> IRBuffer;
   std::unique_ptr<raw_pwrite_stream> IRStream(
       new raw_svector_ostream(IRBuffer));
 
   Compiler.setOutputStream(std::move(IRStream));
-  Compiler.setInvocation(std::move(Invocation));
   Compiler.createDiagnostics(*llvm::vfs::getRealFileSystem());
 
   bool Success = ExecuteCompilerInvocation(&Compiler);
@@ -56,13 +55,12 @@ TEST(FrontendOutputTests, TestVerboseOutputStreamShared) {
       FrontendInputFile("test.cc", Language::CXX));
   Invocation->getFrontendOpts().ProgramAction = EmitBC;
   Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-  CompilerInstance Compiler;
+  CompilerInstance Compiler(std::move(Invocation));
 
   std::string VerboseBuffer;
   raw_string_ostream VerboseStream(VerboseBuffer);
 
   Compiler.setOutputStream(std::make_unique<raw_null_ostream>());
-  Compiler.setInvocation(std::move(Invocation));
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
   Compiler.createDiagnostics(
       *llvm::vfs::getRealFileSystem(),
@@ -87,13 +85,12 @@ TEST(FrontendOutputTests, TestVerboseOutputStreamOwned) {
         FrontendInputFile("test.cc", Language::CXX));
     Invocation->getFrontendOpts().ProgramAction = EmitBC;
     Invocation->getTargetOpts().Triple = "i386-unknown-linux-gnu";
-    CompilerInstance Compiler;
+    CompilerInstance Compiler(std::move(Invocation));
 
     std::unique_ptr<raw_ostream> VerboseStream =
         std::make_unique<raw_string_ostream>(VerboseBuffer);
 
     Compiler.setOutputStream(std::make_unique<raw_null_ostream>());
-    Compiler.setInvocation(std::move(Invocation));
     IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
     Compiler.createDiagnostics(
         *llvm::vfs::getRealFileSystem(),