C++ Intellisense detecting many (possibly unnecessary) problems

[katjie]

• OS and Version: Windows 10
• VS Code Version: 1.28.2
• C/C++ Extension Version: 0.20.1
• Other extensions you installed (and if the issue persists after disabling them): Many installed, disabling them does not help the issue.

I am having trouble with IntelliSense showing many "Problems" in the source code I am working with. The language I am primarily using is C++, and in one file I get the following errors multiple times:

"function call is not allowed in a constant expression" with errorSquiggle under __has_include (__has_include/__has_include__ is defined externally in a gcc library I believe):
#if __has_include(<string_view>) && defined(CATCH_CPP17_OR_GREATER)

"invalid second parameter type ("unsigned long") for literal operator; must be size_t" with errorSquiggle under operator:
inline auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef { return StringRef( rawChars, size );

And this:

among a few others.

These errors all show up when I include catch.hpp from Catch2: ([https://github.com/catchorg/Catch2/blob/master/include/catch.hpp]) within the catch.hpp file. This further causes problems in my own source file with, for example, using the REQUIRE macro from Catch2.

"user-defined literal operator not found" with errorSquiggle under REQUIRE
REQUIRE(add(2, 2) == 4);

I do not believe this is a Catch2 problem, as everything compiles and runs without errors.

If it helps at all, my c_cpp_properties.json file looks like this:
{ "configurations": [ { "name": "Win32", "includePath": [ "${workspaceFolder}/**" ], "defines": [ "_DEBUG", "UNICODE", "_UNICODE" ], "compilerPath": "C:/tools/cygwin64/bin/g++.exe", "intelliSenseMode": "gcc-x64", "cppStandard": "c++17" } ], "version": 4 }

and changing the intelliSenseMode or the compilerPath (to another compiler) does not work.

Opening catch2.hpp alone (outside of any workspace/project folder) also produces these errors.

[sean-mcmanus]

The library you're using is relying heavily on Microsoft extensions, i.e. that don't compile with gcc unless the "-fms-extensions" flag is supported. You can fix this via adding " -fms-extensions" to the end of your compilerPath. However, note that you may encounter "other" bugs, see #2765 ...so far we only know of a bug when typeinfo is used, but there could be more.

Let us know if you're still having issues.

[katjie]

Hi Sean, thank you for the response.

I have tried adding " -fms-extensions" to my compiler path, and while the number of errors is reduced, quite a few continue to exist. The errors that continue to show are those which I mentioned in my initial issue description, so I do not thinking I am encountering new/other bugs by adding this flag.

[sean-mcmanus]

Okay, yeah, I see what you're seeing now. I'm not sure why I saw it become fixed yesterday. It's fixed if you use the "cl.exe" or "clang++.exe" as the compiler in msvc-x64 mode. It looks like our parser in isn't capable of parsing those files correctly in gcc mode.

[katjie]

I have tried to modify my c_cpp_properties.json file to use clang++ and msvc-x64 mode, however I am unfortunately still seeing all of the errors. (I have problems with getting cl.exe on my computer but that's a different problem entirely, however I therefore cannot test if I see the same result with that compiler).

[sean-mcmanus]

Okay, you're right, I'm seem errors with clang++ as well. I'm not sure why I wasn't seeing them before -- it's possible I was using a modified build, i.e. with a different microsoft_version set.

[katjie]

I have noticed that the errors from IntelliSense on Catch2 only show up when you open the file under their directory single_include/catch.hpp, and not the one located at include/catch.hpp, so this might be why you sometimes saw no errors when you are working with my problem.

I have now been able to download cl.exe on my computer, and using this one fixes most of the errors, I am still getting:
"a friend template declaration with a default template argument must be the only declaration" for
friend bool operator == ( const T& lhs, Approx const& rhs ) { auto lhs_v = static_cast<double>(lhs); return rhs.equalityComparisonImpl(lhs_v); }
which was also one of the errors I was seeing previously. This error shows up a few times in the same area of the catch.hpp source code, however it is the only type of error left with the cl/msvc-x64 solution.
However this error does not exist when I compile.

When I work in my test source, I am at least (and so far) no longer seeing errors detected by IntelliSense when I use the Catch2 macros, which will be sufficient enough of a workaround for me as I am not and should not work directly in the catch.hpp file.
However as I am still seeing this problem when I open catch.hpp in vscode, it might still be linked to a bug of sorts in the cpp IntelliSense, regardless of which compilerPath and intellisenseMode are used.

[inbright2alter]

I have encountered a similar kind of issue:

Obviously size_t is a typedef, but intellisense seems to over-expand this typedef and produce an error

Edit: so I checked it out, and it appears so that clang-x64 intellisense setting is triggering this, even though it displays size_t as the same typedef

[sean-mcmanus]

@ldelenger We are tracking that issue with #6343 which in turn is tracking https://developercommunity.visualstudio.com/content/problem/1227674/cc-gives-error-with-gcc-81-string-view-header-due.html .