[lldb][windows] remove duplicate implementation of UTF8ToUTF16

[charles-zablit]

std::wstring AnsiToUtf16(const std::string &ansi) is a reimplementation of llvm::sys::windows::UTF8ToUTF16. This patch removes AnsiToUtf16 and its usages entirely.

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Charles Zablit (charles-zablit)

Changes

std::wstring AnsiToUtf16(const std::string &ansi) is a reimplementation of llvm::sys::windows::UTF8ToUTF16. This patch removes AnsiToUtf16 and its usages entirely.

---

Full diff: https://github.com/llvm/llvm-project/pull/154424.diff

1 Files Affected:

• (modified) lldb/source/Host/windows/Host.cpp (+9-18)

diff --git a/lldb/source/Host/windows/Host.cpp b/lldb/source/Host/windows/Host.cpp
index 4e747f77afc0e..8b76b21f33b29 100644
--- a/lldb/source/Host/windows/Host.cpp
+++ b/lldb/source/Host/windows/Host.cpp
@@ -22,6 +22,7 @@
 #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"
@@ -32,6 +33,8 @@
 using namespace lldb;
 using namespace lldb_private;
 
+using llvm::sys::windows::UTF8ToUTF16;
+
 static bool GetTripleForProcess(const FileSpec &executable,
                                 llvm::Triple &triple) {
   // Open the PE File as a binary file, and parse just enough information to
@@ -325,30 +328,17 @@ class WindowsEventLog {
 
 static llvm::ManagedStatic<WindowsEventLog> event_log;
 
-static std::wstring AnsiToUtf16(const std::string &ansi) {
-  if (ansi.empty())
-    return {};
-
-  const int unicode_length =
-      MultiByteToWideChar(CP_ACP, 0, ansi.c_str(), -1, nullptr, 0);
-  if (unicode_length == 0)
-    return {};
-
-  std::wstring unicode(unicode_length, L'\0');
-  MultiByteToWideChar(CP_ACP, 0, ansi.c_str(), -1, &unicode[0], unicode_length);
-  return unicode;
-}
-
 void Host::SystemLog(Severity severity, llvm::StringRef message) {
   HANDLE h = event_log->GetHandle();
   if (!h)
     return;
 
-  std::wstring wide_message = AnsiToUtf16(message.str());
-  if (wide_message.empty())
+  llvm::SmallVector<wchar_t, 1> argsUTF16;
+  if (UTF8ToUTF16(message.str(), argsUTF16))
     return;
 
-  LPCWSTR msg_ptr = wide_message.c_str();
+  if (argsUTF16.empty())
+    return;
 
   WORD event_type;
   switch (severity) {
@@ -363,5 +353,6 @@ void Host::SystemLog(Severity severity, llvm::StringRef message) {
     event_type = EVENTLOG_INFORMATION_TYPE;
   }
 
-  ReportEventW(h, event_type, 0, 0, nullptr, 1, 0, &msg_ptr, nullptr);
+  LPCWSTR messages[] = {argsUTF16.data()};
+  ReportEventW(h, event_type, 0, 0, nullptr, 1, 0, messages, nullptr);
 }

[compnerd]

I would consider retaining this as &argsUTF16.data() instead of the LPCWSTR[]. Or if you want to use the explicit array, consider replacing the 1 with countof(messages).

[charles-zablit]

Could not get it to compile with the &argsUTF16.data(), because of the following error: cannot convert argument 8 from 'wchar_t **' to 'LPCWSTR *'.

I used a fixed size array and std::size.