windows launcher: Make the launcher compile under mingw

src/main/native/windows/file.cc

@@ -18,11 +18,11 @@
 
 #include "src/main/native/windows/file.h"
 
-#include <WinIoCtl.h>
 #include <stdint.h>  // uint8_t
 #include <versionhelpers.h>
 #include <winbase.h>
 #include <windows.h>
+#include <winioctl.h>
 
 #include <memory>
 #include <sstream>

src/main/native/windows/process.cc

@@ -18,8 +18,8 @@
 
 #include "src/main/native/windows/process.h"
 
+#include <versionhelpers.h>
 #include <windows.h>
-#include <VersionHelpers.h>
 
 #include <memory>
 #include <sstream>

src/tools/launcher/java_launcher.cc

@@ -250,7 +250,7 @@ wstring JavaBinaryLauncher::CreateClasspathJar(const wstring& classpath) {
       binary_base_path + rand_id + L".jar_manifest";
   blaze_util::AddUncPrefixMaybe(&jar_manifest_file_path);
 #if (__cplusplus >= 201703L)
-  wofstream jar_manifest_file(std::filesystem::path(jar_manifest_file_path));
+  wofstream jar_manifest_file{std::filesystem::path(jar_manifest_file_path)};
 #else
   wofstream jar_manifest_file(jar_manifest_file_path);
 #endif

src/tools/launcher/launcher_main.cc

@@ -29,6 +29,9 @@
 #endif
 
 #include <windows.h>
+#include <processenv.h>
+#include <shellapi.h>
+#include <winbase.h>
 
 #include <memory>
 #include <string>
@@ -64,6 +67,24 @@ static std::wstring GetExecutableFileName() {
   return buffer.substr(0, length);
 }
 
+#if defined(__MINGW32__) && not defined(BAZEL_MINGW_UNICODE)
+// MinGW requires linkopt=-municode to use wmain as entry point.
+// The below allows fallback to main when BAZEL_MINGW_UNICODE is not defined.
+// Otherwise, to use wmain directly, one needs to use both linkopt=-municode and
+// copt=-DBAZEL_MINGW_UNICODE.
+int wmain(int argc, wchar_t* argv[]);
+int main() {
+  int argc = 0;
+  wchar_t** argv = CommandLineToArgvW(GetCommandLineW(), &argc);
+  if (argv == nullptr) {
+    die(L"CommandLineToArgvW failed.");
+  }
+  int result = wmain(argc, argv);
+  LocalFree(argv);
+  return result;
+}
+#endif
+
 int wmain(int argc, wchar_t* argv[]) {
   // In case the given binary path is a shortened Windows 8dot3 path, we convert
   // it back to its long path form so that path manipulations (e.g. appending