[Qt-creator] Clang code model running in C++98 mode

[Nikolai Kosjar]

On 11/15/18 3:55 PM, Julius Bullinger wrote:
> Hi Nikolai
> 
> On 06.11.2018 12:19, Nikolai Kosjar wrote:
>> Recently there were some changes in that area. Could you please try
>> again with the updated snapshots for 4.8?
>>
>> http://download.qt.io/snapshots/qtcreator/4.8/4.8.0-beta2
> 
> I managed to built the latest 4.8 branch on my machine, and still got 
> the same issue:
> 
>>> I can't reproduce it with a smaller project, but is there any way I can
>>> debug this issue? Like get the options that are passed from qmake to the
>>> code model?
>>
>> A breakpoint in ProjectInfoGenerator::createProjectPart() should help,
>> especially on
>>
>>     part->languageVersion = macroInspectionReport.languageVersion;
>>
> 
> On the first break after loading the project, 
> macroInspectionReport.languageVersion is CXX14 (7). On further breaks, 
> it's CXX98 (4).
> 
> I cannot find any differences in the respective qmake projects. The 
> flags.commandLineFlags that are passed are the following:
> 
> -nologo -Zc:wchar_t -FS -Zc:rvalueCast -Zc:inline /wd4503 /w14239 /FC 
> /D_LIntStatic /Zi /Fd<path> -O2 -Zi -MD -Zc:strictStrings -W3 -w34100 
> -w34189 -w44996 /WX -EHsc
> 
> However, I found that in tcInfo.macroInspectionRunner, the "__cplusplus" 
> macro has a value of 199711L. This is from msvctoolchain.cpp, which 
> shows some information about the possible values:
> 
> // We want to detect the language version based on the predefined macros.
> // Unfortunately MSVC does not conform to standard when it comes to the 
> predefined
> // __cplusplus macro - it reports "199711L", even for newer language 
> versions.
> //
> // However:
> //   * For >= Visual Studio 2015 Update 3 predefines _MSVC_LANG which 
> has the proper value
> //     of __cplusplus.
> //     See 
> https://docs.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=vs-2017 
> 
> //   * For >= Visual Studio 2017 Version 15.7 __cplusplus is correct 
> once /Zc:__cplusplus
> //     is provided on the command line. Then __cplusplus == _MSVC_LANG.
> //     See 
> https://blogs.msdn.microsoft.com/vcblog/2018/04/09/msvc-now-correctly-reports-__cplusplus 
> 
> //
> // We rely on _MSVC_LANG if possible, otherwise on some hard coded 
> language versions
> // depending on _MSC_VER.
> 
> We're still running MSVC 2013, which doesn't seem to be covered by this 
> exceptions. I tested opening the project with a MSVC 2017 Version 15.8 
> kit, and with that, the code model reports a C++ version of CXX17 
> (although it should be C++11)!
> 
> So, I guess this is a bug in Creator regarding C++ version detection 
> with MSVC 2013?

Looks like that, yes, please report.

For some reason the code path that checks _MSC_VER fails or is never 
executed. Or there is a bug in the macro cache.

Nikolai