A sad workaround for a sad misery with Python bindings on Windows.

doc/changelog.dox

@@ -371,7 +371,9 @@ See also:
     @ref Corrade::Containers::Array instead of being deleted
 -   Global state used by @ref GL::Context and @ref Audio::Context is no longer
     duplicated when Magnum is built statically and linked to more than one
-    dynamic library or executable.
+    dynamic library or executable. This works on all platforms except for
+    Python bindings on Windows at the moment, where the workaround is to build
+    both Corrade and Magnum dynamically.
 -   The [base-qt](https://github.com/mosra/magnum-bootstrap/tree/base-qt)
     bootstrap project is fixed to use OpenGL 4.1 on macOS instead of being
     stuck on 2.1 (see [mosra/magnum-bootstrap#22](https://github.com/mosra/magnum-bootstrap/issues/22))

src/Magnum/Audio/Context.cpp

@@ -161,7 +161,7 @@ namespace {
 Context*& windowsCurrentContext() {
     /* A function-local static to ensure it's only initialized once without any
        race conditions among threads */
-    static Context** const uniqueGlobals = reinterpret_cast<Context**>(Magnum::Implementation::windowsWeakSymbol("magnumAudioUniqueCurrentContext"));
+    static Context** const uniqueGlobals = reinterpret_cast<Context**>(Magnum::Implementation::windowsWeakSymbol("magnumAudioUniqueCurrentContext", &magnumAudioUniqueCurrentContext));
     return *uniqueGlobals;
 }
 

src/Magnum/GL/Context.cpp

@@ -522,7 +522,7 @@ namespace {
 Context*& windowsCurrentContext() {
     /* A function-local static to ensure it's only initialized once without any
        race conditions among threads */
-    static Context*&(*const uniqueGlobals)() = reinterpret_cast<Context*&(*)()>(Magnum::Implementation::windowsWeakSymbol("magnumGLUniqueCurrentContext"));
+    static Context*&(*const uniqueGlobals)() = reinterpret_cast<Context*&(*)()>(Magnum::Implementation::windowsWeakSymbol("magnumGLUniqueCurrentContext", reinterpret_cast<void*>(magnumGLUniqueCurrentContext)));
     return uniqueGlobals();
 }
 

src/Magnum/Implementation/WindowsWeakSymbol.cpp

@@ -25,18 +25,23 @@
 
 #include "WindowsWeakSymbol.h"
 
-#include <Corrade/Utility/Assert.h>
+#include <cstdio>
 
 #define WIN32_LEAN_AND_MEAN 1
 #define VC_EXTRALEAN
 #include <windows.h>
 
 namespace Magnum { namespace Implementation {
 
-void* windowsWeakSymbol(const char* name) {
+void* windowsWeakSymbol(const char* name, void* backup) {
     /* FARPROC?! I want either a function pointer or a variable pointer */
     void* address = reinterpret_cast<void*>(GetProcAddress(GetModuleHandleA(nullptr), name));
-    CORRADE_INTERNAL_ASSERT(address);
+    /* This shouldn't fail, except in Python, where it's a sad, sad misery. */
+    if(!address) {
+        std::fprintf(stderr, "Cannot query global symbol %s and make it unique\n"
+            "across DLLs. App may misbehave, sorry. Build Magnum as dynamic as a workaround.\n", name);
+        address = backup;
+    }
     return address;
 }
 

src/Magnum/Implementation/WindowsWeakSymbol.h

@@ -39,7 +39,7 @@
 
 namespace Magnum { namespace Implementation {
 
-void* windowsWeakSymbol(const char* name);
+void* windowsWeakSymbol(const char* name, void* backup);
 
 }}