Bug 189492 – [Win][Clang][DumpRenderTree] 0 and nullptr can't be implicitly converted to AccessibilityUIElement

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Fujii Hironori]

[Win][Clang][DumpRenderTree] Add a constructor of AccessibilityUIElement for 0 or nullptr

While trying to build WebKit WinCairo port with the latest Clang (Bug 171618),
the following compilation error is reported.

> [9/31] Building CXX object Tools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\AccessibilityUIElement.cpp.obj
> FAILED: Tools/DumpRenderTree/CMakeFiles/DumpRenderTreeLib.dir/AccessibilityUIElement.cpp.obj 
> C:\tools\llvm\bin\clang-cl.exe (...) /FoTools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\AccessibilityUIElement.cpp.obj /FdTools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\ -c ..\..\Tools\DumpRenderTree\AccessibilityUIElement.cpp
> ..\..\Tools\DumpRenderTree\AccessibilityUIElement.cpp(1564,85):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
> AccessibilityUIElement AccessibilityUIElement::horizontalScrollbar() const { return 0; }
>                                                                                     ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(66,5):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
>     AccessibilityUIElement(PlatformUIElement);
>     ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(67,5):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
>     AccessibilityUIElement(const AccessibilityUIElement&);
>     ^
> ..\..\Tools\DumpRenderTree\AccessibilityUIElement.cpp(1565,83):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
> AccessibilityUIElement AccessibilityUIElement::verticalScrollbar() const { return 0; }
>                                                                                   ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(66,5):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
>     AccessibilityUIElement(PlatformUIElement);
>     ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(67,5):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
>     AccessibilityUIElement(const AccessibilityUIElement&);
>     ^
> ..\..\Tools\DumpRenderTree\AccessibilityUIElement.cpp(1566,100):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
> AccessibilityUIElement AccessibilityUIElement::uiElementAttributeValue(JSStringRef) const { return 0; }
>                                                                                                    ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(66,5):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
>     AccessibilityUIElement(PlatformUIElement);
>     ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(67,5):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
>     AccessibilityUIElement(const AccessibilityUIElement&);
>     ^
> ..\..\Tools\DumpRenderTree\AccessibilityUIElement.cpp(1635,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(66,5):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
>     AccessibilityUIElement(PlatformUIElement);
>     ^
> ..\..\Tools\DumpRenderTree/AccessibilityUIElement.h(67,5):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
>     AccessibilityUIElement(const AccessibilityUIElement&);
>     ^
> 4 errors generated.


> [10/31] Building CXX object Tools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\win\AccessibilityUIElementWin.cpp.obj
> FAILED: Tools/DumpRenderTree/CMakeFiles/DumpRenderTreeLib.dir/win/AccessibilityUIElementWin.cpp.obj 
> C:\tools\llvm\bin\clang-cl.exe  (...) /FoTools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\win\AccessibilityUIElementWin.cpp.obj /FdTools\DumpRenderTree\CMakeFiles\DumpRenderTreeLib.dir\ -c ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(136,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(142,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(148,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(156,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(187,16):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>         return 0;
>                ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(192,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(195,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(200,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(210,16):  error: no viable conversion from returned value of type 'nullptr_t' to function return type 'AccessibilityUIElement'
>         return nullptr;
>                ^~~~~~~
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'nullptr_t' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(672,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(682,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(758,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(763,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(768,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(773,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(778,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(783,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(788,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(967,12):  error: no viable conversion from returned value of type 'int' to function return type 'AccessibilityUIElement'
>     return 0;
>            ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(51,25):  note: candidate constructor not viable: no known conversion from 'int' to 'PlatformUIElement' (aka 'COMPtr<IAccessible>') for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(PlatformUIElement element)
>                         ^
> ..\..\Tools\DumpRenderTree\win\AccessibilityUIElementWin.cpp(56,25):  note: candidate constructor not viable: no known conversion from 'int' to 'const AccessibilityUIElement &' for 1st argument
> AccessibilityUIElement::AccessibilityUIElement(const AccessibilityUIElement& other)
>                         ^
> 19 errors generated.

[Fujii Hironori]

I created a repro. This source can be compiled by MSVC, but by GCC and Clang.

https://godbolt.org/z/cL3sGK

[Fujii Hironori]

https://en.cppreference.com/w/cpp/language/implicit_conversion

> 2) zero or one user-defined conversion;

It seems that implicit conversions allows only one user-defined conversion.

[Fujii Hironori]

Created attachment 349377 [details]
Patch

[Alex Christensen]

Comment on attachment 349377 [details]
Patch

replace nullptr with AccessibilityUIElement(nullptr) instead.

[Alex Christensen]

Or maybe replace 0 with { nullptr }.  Something like that.  A windows-specific constructor isn't the answer.

[Fujii Hironori]

Umm, the reason why I don't like your idea is it can cause
compilation errors only for Windows Clang builds while it
compiles on other ports if someone will add a new code just putting
nullptr.

Other ports typedef PlatformUIElement just to a simple pointer.

> typedef AtkObject* PlatformUIElement;

What about an idea not to use COMPtr? Just use IAccessible*.

> typedef IAccessible* PlatformUIElement;

I will submit a propose patch.

[Fujii Hironori]

Created attachment 349509 [details]
WIP patch

Umm. Too many ".get()" without using windows-specific constructor.
I will submit a patch following your propose.

[Fujii Hironori]

Created attachment 349513 [details]
Patch

[Alex Christensen]

Comment on attachment 349513 [details]
Patch

Great!

[WebKit Commit Bot]

Comment on attachment 349513 [details]
Patch

Clearing flags on attachment: 349513

Committed r235941: <https://trac.webkit.org/changeset/235941>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/44386055>