Interconnect: make Emitter working with virtual bases on 32bit Windows.

mosra · Aug 28, 2018 · b83c116 · b83c116
1 parent c18a387
commit b83c116
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Showing 3 changed files with 16 additions and 5 deletions.
diff --git a/doc/corrade-changelog.dox b/doc/corrade-changelog.dox
@@ -79,6 +79,9 @@ namespace Corrade {
 -   Worked around a misoptimization of @ref Utility::Sha1 when using GCC 6 with
     -O3 on Raspberry Pi Model 3 B+ (AArch64) (GCC 8 works properly again). See
     [mosra/corrade#45](https://github.com/mosra/corrade/issues/45).
+-   It was not possible to use the @ref Interconnect::Emitter class with
+    virtual base classes on 32-bit Windows due to an incorrect assumption about
+    member function pointer sizes
 
 @subsection corrade-changelog-latest-docs Documentation
 

diff --git a/src/Corrade/Interconnect/Connection.h b/src/Corrade/Interconnect/Connection.h
@@ -42,7 +42,15 @@ namespace Implementation {
 
     class SignalData {
         public:
-            enum: std::size_t { Size = 2*sizeof(void*)/sizeof(std::size_t) };
+            enum: std::size_t { Size =
+                #ifndef CORRADE_TARGET_WINDOWS
+                2*sizeof(void*)/sizeof(std::size_t)
+                #else
+                /* On MSVC, pointers to members with a virtual base class
+                   are the biggest and have 16 bytes both on 32bit and 64bit. */
+                16/sizeof(std::size_t)
+                #endif
+            };
 
             #ifndef CORRADE_MSVC2017_COMPATIBILITY
             template<class Emitter, class ...Args> SignalData(typename Emitter::Signal(Emitter::*signal)(Args...)): data() {

diff --git a/src/Corrade/Interconnect/Emitter.h b/src/Corrade/Interconnect/Emitter.h
@@ -402,8 +402,8 @@ more information about connections.
      @ref Emitter::signalConnectionCount()
 */
 template<class EmitterObject, class Emitter, class ...Args> Connection connect(EmitterObject& emitter, Interconnect::Emitter::Signal(Emitter::*signal)(Args...), void(*slot)(Args...)) {
-    static_assert(sizeof(Interconnect::Emitter::Signal(Emitter::*)(Args...)) <= 2*sizeof(void*),
-        "Size of member function pointer is incorrectly assumed to be smaller than 2*sizeof(void*)");
+    static_assert(sizeof(Interconnect::Emitter::Signal(Emitter::*)(Args...)) <= sizeof(Implementation::SignalData),
+        "size of member function pointer is incorrectly assumed to be smaller");
     static_assert(std::is_base_of<Emitter, EmitterObject>::value,
         "Emitter object doesn't have given signal");
 
@@ -446,8 +446,8 @@ more information about connections.
 @todo Connecting to signals
 */
 template<class EmitterObject, class Emitter, class Receiver, class ReceiverObject, class ...Args> Connection connect(EmitterObject& emitter, Interconnect::Emitter::Signal(Emitter::*signal)(Args...), ReceiverObject& receiver, void(Receiver::*slot)(Args...)) {
-    static_assert(sizeof(Interconnect::Emitter::Signal(Emitter::*)(Args...)) <= 2*sizeof(void*),
-        "Size of member function pointer is incorrectly assumed to be smaller than 2*sizeof(void*)");
+    static_assert(sizeof(Interconnect::Emitter::Signal(Emitter::*)(Args...)) <= sizeof(Implementation::SignalData),
+        "Size of member function pointer is incorrectly assumed to be smaller");
     static_assert(std::is_base_of<Emitter, EmitterObject>::value,
         "Emitter object doesn't have given signal");
     static_assert(std::is_base_of<Receiver, ReceiverObject>::value,