From 0d205a19dc087768da1e803d8dfde27f12cb9d99 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 26 Jan 2021 01:28:33 +0200
Subject: [PATCH] Fix compile errors from function casts in wgl

Recent gcc versions don't like casting directly between incompatible
function types.
---
 source/graphics/wgl/glcontext.cpp | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/source/graphics/wgl/glcontext.cpp b/source/graphics/wgl/glcontext.cpp
index ebca3f1..6808897 100644
--- a/source/graphics/wgl/glcontext.cpp
+++ b/source/graphics/wgl/glcontext.cpp
@@ -7,6 +7,16 @@
 
 using namespace std;
 
+namespace {
+
+template<typename T>
+T get_proc(const char *name)
+{
+	return reinterpret_cast<T>(reinterpret_cast<void *>(wglGetProcAddress(name)));
+}
+
+}
+
 namespace Msp {
 namespace Graphics {
 
@@ -48,7 +58,7 @@ void GLContext::platform_init(const GLOptions &opts)
 		ContextHandle fake_context = wglCreateContext(dc);
 		wglMakeCurrent(dc, fake_context);
 
-		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = reinterpret_cast<PFNWGLCREATECONTEXTATTRIBSARBPROC>(wglGetProcAddress("wglCreateContextAttribsARB"));
+		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = get_proc<PFNWGLCREATECONTEXTATTRIBSARBPROC>("wglCreateContextAttribsARB");
 		if(!wglCreateContextAttribs)
 			throw unsupported_gl_mode(opts);
 
@@ -100,7 +110,7 @@ GLContext::~GLContext()
 
 void GLContext::set_swap_interval(unsigned i)
 {
-	PFNWGLSWAPINTERVALEXTPROC wglSwapInterval = reinterpret_cast<PFNWGLSWAPINTERVALEXTPROC>(wglGetProcAddress("wglSwapIntervalEXT"));
+	PFNWGLSWAPINTERVALEXTPROC wglSwapInterval = get_proc<PFNWGLSWAPINTERVALEXTPROC>("wglSwapIntervalEXT");
 	if(!wglSwapInterval)
 		throw runtime_error("wglSwapIntervalEXT not found");
 	wglSwapInterval(i);
-- 
2.43.0