[Lldb-commits] [lldb] [lldb][windows] use OutputDebugStringA instead of c to log events (PR #156474)

[Charles Zablit via lldb-commits]

https://github.com/charles-zablit updated https://github.com/llvm/llvm-project/pull/156474

>From ec308302c936c8ce4993ae27f8d5e813e4ac59c9 Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Tue, 2 Sep 2025 16:13:17 +0100
Subject: [PATCH 1/2] [lldb][windows] use OutputDebugStringA instead of
 ReportEventW to log events

---
 lldb/source/Host/windows/Host.cpp | 44 +++++--------------------------
 1 file changed, 7 insertions(+), 37 deletions(-)

diff --git a/lldb/source/Host/windows/Host.cpp b/lldb/source/Host/windows/Host.cpp
index 4277b8edb38e5..8be4596c420a4 100644
--- a/lldb/source/Host/windows/Host.cpp
+++ b/lldb/source/Host/windows/Host.cpp
@@ -22,10 +22,8 @@
 #include "lldb/Utility/StreamString.h"
 #include "lldb/Utility/StructuredData.h"
 
-#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/ConvertUTF.h"
-#include "llvm/Support/ManagedStatic.h"
 
 // Windows includes
 #include <tlhelp32.h>
@@ -308,52 +306,24 @@ Environment Host::GetEnvironment() {
   return env;
 }
 
-/// Manages the lifecycle of a Windows Event's Source.
-/// The destructor will call DeregisterEventSource.
-/// This class is meant to be used with \ref llvm::ManagedStatic.
-class WindowsEventLog {
-public:
-  WindowsEventLog() : handle(RegisterEventSource(nullptr, L"lldb")) {}
-
-  ~WindowsEventLog() {
-    if (handle)
-      DeregisterEventSource(handle);
-  }
-
-  HANDLE GetHandle() const { return handle; }
-
-private:
-  HANDLE handle;
-};
-
-static llvm::ManagedStatic<WindowsEventLog> event_log;
-
 void Host::SystemLog(Severity severity, llvm::StringRef message) {
   if (message.empty())
     return;
 
-  HANDLE h = event_log->GetHandle();
-  if (!h)
-    return;
-
-  llvm::SmallVector<wchar_t, 1> argsUTF16;
-  if (UTF8ToUTF16(message.str(), argsUTF16))
-    return;
-
-  WORD event_type;
+  std::string log_prefix;
   switch (severity) {
   case lldb::eSeverityWarning:
-    event_type = EVENTLOG_WARNING_TYPE;
+    log_prefix = "[Warning] ";
     break;
   case lldb::eSeverityError:
-    event_type = EVENTLOG_ERROR_TYPE;
+    log_prefix = "[Error] ";
     break;
   case lldb::eSeverityInfo:
   default:
-    event_type = EVENTLOG_INFORMATION_TYPE;
+    log_prefix = "[Info] ";
+    break;
   }
 
-  LPCWSTR messages[1] = {argsUTF16.data()};
-  ReportEventW(h, event_type, 0, 0, nullptr, std::size(messages), 0, messages,
-               nullptr);
+  std::string final_message = log_prefix + message.str();
+  OutputDebugStringA(final_message.c_str());
 }

>From be11dc3b8c516c6305b074ecf6f0cb1a76935bae Mon Sep 17 00:00:00 2001
From: Charles Zablit <c_zablit at apple.com>
Date: Tue, 2 Sep 2025 17:57:17 +0100
Subject: [PATCH 2/2] fixup! [lldb][windows] use OutputDebugStringA instead of
 ReportEventW to log events

---
 lldb/source/Host/windows/Host.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lldb/source/Host/windows/Host.cpp b/lldb/source/Host/windows/Host.cpp
index 8be4596c420a4..e8973a3fb937a 100644
--- a/lldb/source/Host/windows/Host.cpp
+++ b/lldb/source/Host/windows/Host.cpp
@@ -310,20 +310,24 @@ void Host::SystemLog(Severity severity, llvm::StringRef message) {
   if (message.empty())
     return;
 
-  std::string log_prefix;
+  std::string log_msg;
+  llvm::raw_string_ostream stream(log_msg);
+
   switch (severity) {
   case lldb::eSeverityWarning:
-    log_prefix = "[Warning] ";
+    stream << "[Warning] ";
     break;
   case lldb::eSeverityError:
-    log_prefix = "[Error] ";
+    stream << "[Error] ";
     break;
   case lldb::eSeverityInfo:
   default:
-    log_prefix = "[Info] ";
+    stream << "[Info] ";
     break;
   }
 
-  std::string final_message = log_prefix + message.str();
-  OutputDebugStringA(final_message.c_str());
+  stream << message;
+  stream.flush();
+
+  OutputDebugStringA(log_msg.c_str());
 }