[clang] Remove intrusive reference count from `DiagnosticOptions` (#139584)

The `DiagnosticOptions` class is currently intrusively
reference-counted, which makes reasoning about its lifetime very
difficult in some cases. For example, `CompilerInvocation` owns the
`DiagnosticOptions` instance (wrapped in `llvm::IntrusiveRefCntPtr`) and
only exposes an accessor returning `DiagnosticOptions &`. One would
think this gives `CompilerInvocation` exclusive ownership of the object,
but that's not the case:

```c++
void shareOwnership(CompilerInvocation &CI) {
  llvm::IntrusiveRefCntPtr<DiagnosticOptions> CoOwner = &CI.getDiagnosticOptions();
  // ...
}
```

This is a perfectly valid pattern that is being actually used in the
codebase.

I would like to ensure the ownership of `DiagnosticOptions` by
`CompilerInvocation` is guaranteed to be exclusive. This can be
leveraged for a copy-on-write optimization later on. This PR changes
usages of `DiagnosticOptions` across `clang`, `clang-tools-extra` and
`lldb` to not be intrusively reference-counted.

1 files changed, 9 insertions, 6 deletions

diff --git a/clang/unittests/Interpreter/InterpreterTest.cpp b/clang/unittests/Interpreter/InterpreterTest.cpp
index 03b9c33..b97f5ae 100644
--- a/clang/unittests/Interpreter/InterpreterTest.cpp
+++ b/clang/unittests/Interpreter/InterpreterTest.cpp
@@ -95,8 +95,9 @@ TEST_F(InterpreterTest, Errors) {
   // Create the diagnostic engine with unowned consumer.
   std::string DiagnosticOutput;
   llvm::raw_string_ostream DiagnosticsOS(DiagnosticOutput);
-  auto DiagPrinter = std::make_unique<TextDiagnosticPrinter>(
-      DiagnosticsOS, new DiagnosticOptions());
+  DiagnosticOptions DiagOpts;
+  auto DiagPrinter =
+      std::make_unique<TextDiagnosticPrinter>(DiagnosticsOS, DiagOpts);
 
   auto Interp = createInterpreter(ExtraArgs, DiagPrinter.get());
   auto Err = Interp->Parse("intentional_error v1 = 42; ").takeError();
@@ -126,8 +127,9 @@ TEST_F(InterpreterTest, DeclsAndStatements) {
   // Create the diagnostic engine with unowned consumer.
   std::string DiagnosticOutput;
   llvm::raw_string_ostream DiagnosticsOS(DiagnosticOutput);
-  auto DiagPrinter = std::make_unique<TextDiagnosticPrinter>(
-      DiagnosticsOS, new DiagnosticOptions());
+  DiagnosticOptions DiagOpts;
+  auto DiagPrinter =
+      std::make_unique<TextDiagnosticPrinter>(DiagnosticsOS, DiagOpts);
 
   auto Interp = createInterpreter(ExtraArgs, DiagPrinter.get());
   auto R1 = Interp->Parse(
@@ -148,8 +150,9 @@ TEST_F(InterpreterTest, UndoCommand) {
   // Create the diagnostic engine with unowned consumer.
   std::string DiagnosticOutput;
   llvm::raw_string_ostream DiagnosticsOS(DiagnosticOutput);
-  auto DiagPrinter = std::make_unique<TextDiagnosticPrinter>(
-      DiagnosticsOS, new DiagnosticOptions());
+  DiagnosticOptions DiagOpts;
+  auto DiagPrinter =
+      std::make_unique<TextDiagnosticPrinter>(DiagnosticsOS, DiagOpts);
 
   auto Interp = createInterpreter(ExtraArgs, DiagPrinter.get());