Reapply "[NFC] Explicitly pass a VFS when creating DiagnosticsEngine (#115852)"

This reverts commit a1153cd6fedd4c906a9840987934ca4712e34cb2 with fixes
to lldb breakages.

Fixes https://github.com/llvm/llvm-project/issues/117145.

5 files changed, 23 insertions, 20 deletions

diff --git a/clang/unittests/Serialization/ForceCheckFileInputTest.cpp b/clang/unittests/Serialization/ForceCheckFileInputTest.cpp
index ad8892b..6a839d1 100644
--- a/clang/unittests/Serialization/ForceCheckFileInputTest.cpp
+++ b/clang/unittests/Serialization/ForceCheckFileInputTest.cpp
@@ -63,12 +63,14 @@ export int aa = 43;
   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();
 
+    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+        CompilerInstance::createDiagnostics(*CIOpts.VFS,
+                                            new DiagnosticOptions());
+    CIOpts.Diags = Diags;
+
     const char *Args[] = {"clang++",       "-std=c++20",
                           "--precompile",  "-working-directory",
                           TestDir.c_str(), "a.cppm"};
@@ -103,11 +105,12 @@ export int aa = 43;
   }
 
   {
-    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-        CompilerInstance::createDiagnostics(new DiagnosticOptions());
     CreateInvocationOptions CIOpts;
-    CIOpts.Diags = Diags;
     CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+    IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+        CompilerInstance::createDiagnostics(*CIOpts.VFS,
+                                            new DiagnosticOptions());
+    CIOpts.Diags = Diags;
 
     std::string BMIPath = llvm::Twine(TestDir + "/a.pcm").str();
     const char *Args[] = {
diff --git a/clang/unittests/Serialization/ModuleCacheTest.cpp b/clang/unittests/Serialization/ModuleCacheTest.cpp
index a7ca985..6ceee1c 100644
--- a/clang/unittests/Serialization/ModuleCacheTest.cpp
+++ b/clang/unittests/Serialization/ModuleCacheTest.cpp
@@ -106,11 +106,11 @@ TEST_F(ModuleCacheTest, CachedModuleNewPath) {
 
   SmallString<256> MCPArg("-fmodules-cache-path=");
   MCPArg.append(ModuleCachePath);
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
-  CIOpts.Diags = Diags;
   CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(*CIOpts.VFS, new DiagnosticOptions());
+  CIOpts.Diags = Diags;
 
   // First run should pass with no errors
   const char *Args[] = {"clang",        "-fmodules",          "-Fframeworks",
@@ -156,11 +156,11 @@ TEST_F(ModuleCacheTest, CachedModuleNewPathAllowErrors) {
 
   SmallString<256> MCPArg("-fmodules-cache-path=");
   MCPArg.append(ModuleCachePath);
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
-  CIOpts.Diags = Diags;
   CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(*CIOpts.VFS, new DiagnosticOptions());
+  CIOpts.Diags = Diags;
 
   // First run should pass with no errors
   const char *Args[] = {"clang",        "-fmodules",          "-Fframeworks",
diff --git a/clang/unittests/Serialization/NoCommentsTest.cpp b/clang/unittests/Serialization/NoCommentsTest.cpp
index a0a564a..a1fb234 100644
--- a/clang/unittests/Serialization/NoCommentsTest.cpp
+++ b/clang/unittests/Serialization/NoCommentsTest.cpp
@@ -83,11 +83,11 @@ export module Comments;
 void foo() {}
   )cpp");
 
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
-  CIOpts.Diags = Diags;
   CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(*CIOpts.VFS, new DiagnosticOptions());
+  CIOpts.Diags = Diags;
 
   std::string CacheBMIPath = llvm::Twine(TestDir + "/Comments.pcm").str();
   const char *Args[] = {"clang++",       "-std=c++20",
diff --git a/clang/unittests/Serialization/PreambleInNamedModulesTest.cpp b/clang/unittests/Serialization/PreambleInNamedModulesTest.cpp
index d26e1cb..cf317ed 100644
--- a/clang/unittests/Serialization/PreambleInNamedModulesTest.cpp
+++ b/clang/unittests/Serialization/PreambleInNamedModulesTest.cpp
@@ -75,10 +75,10 @@ export using ::E;
   )cpp",
           MainFilePath);
 
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS =
       llvm::vfs::createPhysicalFileSystem();
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(*VFS, new DiagnosticOptions());
 
   CreateInvocationOptions CIOpts;
   CIOpts.Diags = Diags;
diff --git a/clang/unittests/Serialization/VarDeclConstantInitTest.cpp b/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
index 5cbbfb9..14c0c30 100644
--- a/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
+++ b/clang/unittests/Serialization/VarDeclConstantInitTest.cpp
@@ -90,11 +90,11 @@ export namespace Fibonacci
 }
   )cpp");
 
-  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
-      CompilerInstance::createDiagnostics(new DiagnosticOptions());
   CreateInvocationOptions CIOpts;
-  CIOpts.Diags = Diags;
   CIOpts.VFS = llvm::vfs::createPhysicalFileSystem();
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags =
+      CompilerInstance::createDiagnostics(*CIOpts.VFS, new DiagnosticOptions());
+  CIOpts.Diags = Diags;
 
   const char *Args[] = {"clang++",       "-std=c++20",
                         "--precompile",  "-working-directory",