Intellisense not recognizing constexpr methods of captured values in lambda

[lanyizi]

Type: LanguageService

Describe the bug

• OS and Version: Windows 10 18362
• VS Code Version: 1.41.1
• C/C++ Extension Version: 0.26.3
• I have CMake tools installed

To Reproduce

1. Write

auto array = std::array<int, 4>{};
array = [&array]{ return std::array<int, array.size()>{}; }();

2. Intellisense will say "Expression must have constant value -- *this cannot be used as constant value"
   (For some reason my Intellisense won't give error messages in English, that error message above is translated from Chinese "表达式必须含有常量值 -- *this 的值不能用作常数")

Expected behavior

This shouldn't be flagged as an error since it's valid:

Screenshots

Additional context
Cpp Properties:

{
  "compilerPath": "C:/MyMinGW/i686-9.2.0-static-release-win32-dwarf-rt_v6/mingw32/bin/gcc.exe",
  "cStandard": "c11",
  "cppStandard": "c++17",
  "configurationProvider": "vector-of-bool.cmake-tools",
  "compileCommands": "${workspaceFolder}/build/compile_commands.json"
}

[Colengms]

Hi @BSG-75 . I see that you are specifying compilerPath, configurationProvider, and compileCommands. These are mutually exclusive. I'd suggest using only one of them, and removing the other 2 to avoid confusion.

I believe the configurationProvider takes precedence. CMake Tools provides an intelliSense mode. I suspect it was configured to use cl.exe, and provided an MSVC intelliSense mode. MSVC intelliSense mode will squiggle the code you specified, as cl.exe will report the same error when compiling. With a gcc or clang intelliSense mode, you should not see that squiggle.

The "C/C++: Log Diagnostics" command will indicate how intelliSense is configured, including compiler and intelliSense mode.

If this does not explain what you are seeing, could you set "C_Cpp.loggingLevel": "Debug", and provide your C/C++ output, as well as the output of Log Diagnostics?

[Colengms]

This looks like an intelliSense bug. It also repro's in VS, so I opened a bug here. (The C/C++ Extensions shares intelliSense code with VS)

I had reduced your repro to avoid using std::array, and apparently that reduced it too much to repro the issue. I was able to repro without std::array with the code below:

template <int i>
class A
{
public:
	constexpr int size() const  { return i; }
};

void foo()
{
	auto a1 = A<4>{};
	auto a2 = A<a1.size()>{};
	auto a3 = [&]() { return A<a1.size()>{}; }; // <- Squiggles on 'a1'
}

[bobbrow]

The VS ticket ended up on the MSVC compiler team instead of going to EDG. I opened a new internal bug (2263543) so that EDG could be made aware that this is not working in gcc/clang mode.