[lldb][unittests] Add once_flag to initialization of debugger in testing support (#8141)

* [lldb][unittest] Add call_once flag to initialize debugger (llvm#80786)

I tried adding a new unit test to the core test
suite (llvm#79533) but it broke the
test suite on AArch64 Linux due to hitting an assertion for calling
`Debugger::Initialize` more than once. When the unit test suite is
invoked as a standalone binary the test suite state is shared, and
`Debugger::Initialize` gets called in `DiagnosticEventTest.cpp` before
being called in `ProgressReportTest.cpp`.

`DiagnosticEventTest.cpp` uses a call_once flag to initialize the
debugger but it's local to that test. This commit adds a once_flag to
`TestUtilities` so that `Debugger::Initialize` can be called once by the
tests that use it.

(cherry picked from commit 3885483)

* [lldb][unittest] Use shared once_flag in DiagnosticEventTest (llvm#80788)

Incorporates the changes from
llvm#80786 to use a once_flag from
`TestUtilities` instead of a local flag in order to prevent hitting an
assertion that the debugger was initialized again in another test.

(cherry picked from commit 5690027)

Author: chelcassanova

lldb/unittests/Core/DiagnosticEventTest.cpp

@@ -11,6 +11,7 @@
 #include "Plugins/Platform/MacOSX/PlatformMacOSX.h"
 #include "Plugins/Platform/MacOSX/PlatformRemoteMacOSX.h"
 #include "TestingSupport/SubsystemRAII.h"
+#include "TestingSupport/TestUtilities.h"
 #include "lldb/Core/Debugger.h"
 #include "lldb/Core/DebuggerEvents.h"
 #include "lldb/Host/FileSystem.h"
@@ -26,16 +27,14 @@ using namespace lldb_private::repro;
 static const constexpr std::chrono::seconds TIMEOUT(0);
 static const constexpr size_t DEBUGGERS = 3;
 
-static std::once_flag debugger_initialize_flag;
-
 namespace {
 class DiagnosticEventTest : public ::testing::Test {
 public:
   void SetUp() override {
     FileSystem::Initialize();
     HostInfo::Initialize();
     PlatformMacOSX::Initialize();
-    std::call_once(debugger_initialize_flag,
+    std::call_once(TestUtilities::g_debugger_initialize_flag,
                    []() { Debugger::Initialize(nullptr); });
     ArchSpec arch("x86_64-apple-macosx-");
     Platform::SetHostPlatform(

lldb/unittests/TestingSupport/TestUtilities.cpp

@@ -19,6 +19,7 @@ using namespace lldb_private;
 
 extern const char *TestMainArgv0;
 
+std::once_flag TestUtilities::g_debugger_initialize_flag;
 std::string lldb_private::GetInputFilePath(const llvm::Twine &name) {
   llvm::SmallString<128> result = llvm::sys::path::parent_path(TestMainArgv0);
   llvm::sys::fs::make_absolute(result);

lldb/unittests/TestingSupport/TestUtilities.h

@@ -31,6 +31,11 @@
 namespace lldb_private {
 std::string GetInputFilePath(const llvm::Twine &name);
 
+class TestUtilities {
+public:
+  static std::once_flag g_debugger_initialize_flag;
+};
+
 class TestFile {
 public:
   static llvm::Expected<TestFile> fromYaml(llvm::StringRef Yaml);
@@ -51,6 +56,6 @@ class TestFile {
 
   std::string Buffer;
 };
-}
+} // namespace lldb_private
 
 #endif