From 37418eed8e9b8f91c802f8c1bbb45b630f190cd8 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Fri, 28 Oct 2022 19:37:05 +0100
Subject: [PATCH] Replace wxWritableCharBuffer template with 2 simpler classes

This addresses a FIXME comment in this template, it was written in a
generic form to compile in both Unicode and ANSI builds of the library,
but now it can be written more simply and efficiently (in the "char"
case).

No real changes.
---
 include/wx/buffer.h | 32 ++++++++++++++++----------------
 include/wx/string.h |  5 +++--
 2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/include/wx/buffer.h b/include/wx/buffer.h
index 619fd32d55..2224c5bd3a 100644
--- a/include/wx/buffer.h
+++ b/include/wx/buffer.h
@@ -388,27 +388,27 @@ public:
     wxWCharBuffer(const wxCStrData& cstr);
 };
 
-// wxCharTypeBuffer<T> implicitly convertible to T*
-template <typename T>
-class wxWritableCharTypeBuffer : public wxCharTypeBuffer<T>
+// wxCharTypeBuffer<T> implicitly convertible to T*, for char and wchar_t,
+// implemented slightly differently because in one case we must be
+// constructible from a buffer and in another -- from a raw pointer.
+
+class wxWritableCharBuffer : public wxScopedCharTypeBuffer<char>
 {
 public:
-    typedef typename wxScopedCharTypeBuffer<T>::CharType CharType;
+    explicit wxWritableCharBuffer(const wxScopedCharTypeBuffer<char>& src)
+        : wxScopedCharTypeBuffer<char>(src) {}
 
-    wxWritableCharTypeBuffer(const wxScopedCharTypeBuffer<T>& src)
-        : wxCharTypeBuffer<T>(src) {}
-    // FIXME-UTF8: this won't be needed after converting mb_str()/wc_str() to
-    //             always return a buffer
-    //             + we should derive this class from wxScopedCharTypeBuffer
-    //               then
-    wxWritableCharTypeBuffer(const CharType *str = nullptr)
-        : wxCharTypeBuffer<T>(str) {}
-
-    operator CharType*() { return this->data(); }
+    operator char*() { return data(); }
 };
 
-typedef wxWritableCharTypeBuffer<char> wxWritableCharBuffer;
-typedef wxWritableCharTypeBuffer<wchar_t> wxWritableWCharBuffer;
+class wxWritableWCharBuffer : public wxCharTypeBuffer<wchar_t>
+{
+public:
+    explicit wxWritableWCharBuffer(const CharType *str)
+        : wxCharTypeBuffer<wchar_t>(str) {}
+
+    operator wchar_t*() { return data(); }
+};
 
 
 // Compatibility defines, don't use them in the new code.
diff --git a/include/wx/string.h b/include/wx/string.h
index e10b95f285..02bcde0a10 100644
--- a/include/wx/string.h
+++ b/include/wx/string.h
@@ -1572,8 +1572,9 @@ public:
     // returned buffer won't affect the string, these methods are only useful
     // for passing values to const-incorrect functions
     wxWritableCharBuffer char_str(const wxMBConv& conv wxSTRING_DEFAULT_CONV_ARG) const
-        { return mb_str(conv); }
-    wxWritableWCharBuffer wchar_str() const { return wc_str(); }
+        { return wxWritableCharBuffer(mb_str(conv)); }
+    wxWritableWCharBuffer wchar_str() const
+        { return wxWritableWCharBuffer(wc_str()); }
 
     // conversion to the buffer of the given type T (= char or wchar_t) and
     // also optionally return the buffer length