Errors when compiling with msvc

[aquiles2k]

Hi, i still can't get msvc to compile webkit for qt5.

With the help of @quarcko and others i already smashed a lot of errors but there are still some left and i have not yet found out how to fix these.

Error 1:

You've instantiated std::aligned_storage<Len, Align> with an extended alignment (in other words, Align > alignof(max_align_t)). 
Before VS 2017 15.8, the member "type" would non-conformingly have an alignment of only alignof(max_align_t). VS 2017 15.8 was fixed to handle this correctly, 
but the fix inherently changes layout and breaks binary compatibility (*only* for uses of aligned_storage with extended alignments). 
Please define either (1) _ENABLE_EXTENDED_ALIGNED_STORAGE to acknowledge that you understand this message and that you actually want a type with an extended alignment, 
or (2) _DISABLE_EXTENDED_ALIGNED_STORAGE to silence this message and get the old non-conforming behavior. 

(compiling source file D:\Dev\Builds\qtwebkitcmake\WebCore\DerivedSources\unified-sources\UnifiedSource-c57e08af-5.cpp)	WebCore (WebCore\WebCore)	
C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30133\include\type_traits

Error 2:

'WebCore::XMLDocumentParserScope::XMLDocumentParserScope(WebCore::CachedResourceLoader *,xmlGenericErrorFunc,xmlStructuredErrorFunc,void *)': 
cannot convert argument 3 from 'void (__cdecl *)(void *,xmlError *)' to 'xmlStructuredErrorFunc'

(compiling source file D:\Dev\Builds\qtwebkitcmake\WebCore\DerivedSources\unified-sources\UnifiedSource-42f7b70e-2.cpp) WebCore (WebCore\WebCore)	
D:\Dev\Sources\qtwebkit-2022-09-07-src\Source\WebCore\xml\XSLStyleSheetLibxslt.cpp	143	

Error 3:

'void xmlSetStructuredErrorFunc(void *,xmlStructuredErrorFunc)': 
cannot convert argument 2 from 'void (__cdecl *)(void *,xmlError *)' to 'xmlStructuredErrorFunc' 

(compiling source file D:\Dev\Builds\qtwebkitcmake\WebCore\DerivedSources\unified-sources\UnifiedSource-42f7b70e-2.cpp)	WebCore (WebCore\WebCore)	
D:\Dev\Sources\qtwebkit-2022-09-07-src\Source\WebCore\xml\XSLTProcessorLibxslt.cpp	134	

Error 4:

missing type specifier - int assumed. Note: C++ does not support default-int	

WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\WebCore\PrivateHeaders\WebCore\ProgressTrackerClient.h	33	

So does anyone know how to fix these? Thanks and best wishes!

[aquiles2k]

Only error 4 remaining.

I fixed error 1 by defining _ENABLE_EXTENDED_ALIGNED_STORAGE as sugested though i dont know what implications this has.

I fixed error 2 and 3 by adding a missing const to XSLTProcessor::parseErrorFunc in .cpp and .h

I still don't know for error 4. ProgressTrackerClient.h looks like:

namespace WebCore {

class Frame;

class ProgressTrackerClient {
    WTF_MAKE_FAST_ALLOCATED;
public:

The error is in the macro WTF_MAKE_FAST_ALLOCATED which expands to some crazy code overwriting new and delete operators.

[quarcko]

Sorry i did not encounter any of these errors on my build with MINGW.
But maybe you should try building "qt6" or "qt6-gha" branches as code
in ProgressTrackerClient.h is different than the one you are building...

[aquiles2k]

After expanding the macro to actual code i found a fix for error 4 by just adding a <WTF/FastMalloc.h> include.

Now the next thing are linker errors for WebKitLegacy with QWebPluginFactory in FrameLoaderClientQt.obj and QWebPageAdapter.obj:

Severity	Code	Description	Project	File	Line	Suppression State
Error	LNK2019	unresolved external symbol "public: bool __cdecl QWebPluginFactory::MimeType::operator==(struct QWebPluginFactory::MimeType const &)const " (??8MimeType@QWebPluginFactory@@QEBA_NAEBU01@@Z) referenced in function "public: bool __cdecl QWebPluginFactory::MimeType::operator!=(struct QWebPluginFactory::MimeType const &)const " (??9MimeType@QWebPluginFactory@@QEBA_NAEBU01@@Z)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\FrameLoaderClientQt.obj	1	
Error	LNK2001	unresolved external symbol "public: bool __cdecl QWebPluginFactory::MimeType::operator==(struct QWebPluginFactory::MimeType const &)const " (??8MimeType@QWebPluginFactory@@QEBA_NAEBU01@@Z)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\QWebPageAdapter.obj	1	
Error	LNK2019	unresolved external symbol "public: __cdecl QWebPluginFactory::QWebPluginFactory(class QObject *)" (??0QWebPluginFactory@@QEAA@PEAVQObject@@@Z) referenced in function "public: void __cdecl QWebPluginFactory::`default constructor closure'(void)" (??_FQWebPluginFactory@@QEAAXXZ)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\FrameLoaderClientQt.obj	1	
Error	LNK2001	unresolved external symbol "public: __cdecl QWebPluginFactory::QWebPluginFactory(class QObject *)" (??0QWebPluginFactory@@QEAA@PEAVQObject@@@Z)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\QWebPageAdapter.obj	1	
Error	LNK2019	unresolved external symbol "public: static struct QMetaObject const QWebPluginFactory::staticMetaObject" (?staticMetaObject@QWebPluginFactory@@2UQMetaObject@@B) referenced in function "public: static class QString __cdecl QWebPluginFactory::tr(char const *,char const *,int)" (?tr@QWebPluginFactory@@SA?AVQString@@PEBD0H@Z)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\FrameLoaderClientQt.obj	1	
Error	LNK2001	unresolved external symbol "public: static struct QMetaObject const QWebPluginFactory::staticMetaObject" (?staticMetaObject@QWebPluginFactory@@2UQMetaObject@@B)	WebKitLegacy (WebKitLegacy\WebKitLegacy)	D:\Dev\Builds\qtwebkitcmake\Source\WebKitLegacy\QWebPageAdapter.obj	1	

Can the WebPlugins be disabled?

[aquiles2k]

Ok, i finally had time again to look into this. I fixed the linker errors by adding missing "qt/Api/qwebpluginfactory.cpp" to the sources in "Source/WebKitLegacy/PlatformQt.cmake" and it finished compiling.

Unfortunately the QtTestBrowser is only able to display basic webpages. When any javascript is involved it renders nothing. Thats strange because according to CMakeCache.txt it was built with jit enabled.

As this is the 22-09-07 tag i'm now trying the master branch as well as setting up qt6 and its branch to try and see if that makes a difference.

@mnutt Are you able to open complex pages like google maps with you qt6 build?

[JulienMaille]

@aquiles2k would you have recommendations where to look for guidelines on how to compile this on Windows? Last time I compiled QWebkit was many years ago from Annulen repository and it was relying a lot on dead Conan repositories.
Thanks in advance

[aquiles2k]

@JulienMaille I'm sorry but we decided to make the (costly and time-consuming) switch to QWebEngine, so i can't help you.

[JulienMaille]

@aquiles2k Thanks a lot for your reply. May I just ask

• why was it so costly to switch to QWebEngine?
• do you have remaining notes or pointers on how to compile QWebkit for qt5. Do you make use of the perl script, the cmake file, or anything else? Any small tip will be appreciated!

[aquiles2k]

@JulienMaille

• We are painting on top of a google map while still remaining clicking and zooming, that had to be rewritten since all the event handling changed
• We are using a lot of js for geospatial calculations, that had to be rewritten since js handling changed from synchronous to asynchronous
• printing was a problem and i think the whole communication with the website was rewritten to use websockets?

Thats just out of my head, there was propably more :)

Sorry no notes, i just recently made a lot of space on my drive by deleting all the corresponding build folders.

As far as i remember i "just" used the cmake files (which then in the build process used perl stuff). When errors occured i simply looked here through the patches if anything similar was fixed or i dug through the official WebKit-History searching where and when certain elements were changed.

[JulienMaille]

@aquiles2k thanks again, may I ask if you recompile QWebEngine yourself on Windows? That was my first try but for some reason the compiled plugin silently fails to properly load pages or print them to pdf.

[aquiles2k]

@JulienMaille We once had our own compiled versions of qt plus patches but fortunately we can now use stock qt again which saves us a lot of time for maintaining stuff. So no, we don't compile QWebEngine and just use prebuilt binaries.