From 3d56ea09228ac2989eb8b89c8b69909603d61c3e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Wed, 20 Jul 2022 02:24:40 +0200
Subject: Use template instead of Win32Error::twhat.

---
 c/common.cpp | 24 ++++++++++--------------
 c/common.h   |  6 +++---
 c/main.cpp   |  2 +-
 3 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/c/common.cpp b/c/common.cpp
index 7981801..ba52f2c 100644
--- a/c/common.cpp
+++ b/c/common.cpp
@@ -14,36 +14,32 @@ Win32Error::~Win32Error()
 		HeapFree(GetProcessHeap(), 0, m_wszMsg);
 }
 
-const char* Win32Error::what() const noexcept 
+template <>
+const char* Win32Error::what() const noexcept
 {
 	if (!m_szMsg)
 		FormatMessageA(
 		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
 		    NULL,
 		    m_dwErr,
-		    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
 		    (char*)&m_szMsg,
 		    0, NULL);
 	return m_szMsg;
 }
 
-const TCHAR* Win32Error::twhat() const noexcept 
+template <>
+const wchar_t* Win32Error::what() const noexcept
 {
-#ifdef UNICODE
-#define M m_wszMsg
-#else
-#define M m_szMsg
-#endif
-	if (!M)
-		FormatMessage(
+	if (!m_wszMsg)
+		FormatMessageW(
 		    FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS,
 		    NULL,
 		    m_dwErr,
-		    MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-		    (TCHAR*)&M,
+		    MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
+		    (wchar_t*)&m_wszMsg,
 		    0, NULL);
-	return M;
-#undef M
+	return m_wszMsg;
 }
 
 /* Library: Wrapper for loading and freeing dynamically linked libraries. */
diff --git a/c/common.h b/c/common.h
index 6b29ed5..d84590d 100644
--- a/c/common.h
+++ b/c/common.h
@@ -17,8 +17,8 @@ struct Win32Error : public std::exception
 {
 	Win32Error(DWORD dwErr);
 	~Win32Error();
-	virtual const char* what() const noexcept override;
-	virtual const TCHAR* twhat() const noexcept;
+	template <typename T = char> const T* what() const noexcept;
+
 private:
 	DWORD m_dwErr;
 	char* m_szMsg = NULL;
@@ -69,7 +69,7 @@ inline auto prefer(T... xs)
 	try {
 		return require<F>(xs...);
 	} catch (Win32Error& e) {
-		EBMessageBox(e.twhat(), TEXT("System Error"), MB_ICONWARNING);
+		EBMessageBox(e.what<TCHAR>(), TEXT("System Error"), MB_ICONWARNING);
 		return (decltype(F(std::declval<T>()...)))NULL;
 	}
 }
diff --git a/c/main.cpp b/c/main.cpp
index a72de53..541f524 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -60,7 +60,7 @@ void OnTerminate() noexcept
 			    "Fatal Error", MB_ICONERROR);
 	} catch (Win32Error& e) {
 		std::basic_string<TCHAR> tstr = TEXT("The program was terminated due to a Windows error: ");
-		tstr += e.twhat();
+		tstr += e.what<TCHAR>();
 		MessageBox(NULL, tstr.c_str(), TEXT("Fatal Error"), MB_ICONERROR);
 	} catch (std::exception& e) {
 		std::string str = "The program was terminated due to an exception: ";
-- 
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