Vscode-cpptools: C++ parsing error (not)?

[python152]

• VSCode Version: 1.27
• OS Version: Mac OS 10.13.6

Steps to Reproduce:

The following code seems giving vscode a hard time to parse -

    // hist_bins is vector container
    auto idx = std::lower_bound(hist_bins.begin(), hist_bins.end(), val) - hist_bins.begin();

I think this is valid code, isn't it?

{
    "resource": "/Users/xyz/test.cc",
    "owner": "_generated_diagnostic_collection_name_#0",
    "code": "undefined",
    "severity": 8,
    "message": "more than one operator \"-\" matches these operands: -- function template \"auto std::__1::operator-(const std::__1::__wrap_iter<_Iter1> &__x, const std::__1::__wrap_iter<_Iter2> &__y)-><error-type>\" -- function template \"auto std::__1::operator-(const std::__1::__wrap_iter<_Iter1> &__x, const std::__1::__wrap_iter<_Iter2> &__y)->decltype(((__x.std::__1::__wrap_iter<_Iter>::base()) - (__y.std::__1::__wrap_iter<_Iter>::base())))\" -- operand types are: std::__1::__wrap_iter<uint64_t *> - std::__1::__wrap_iter<uint64_t *>",
    "startLineNumber": 125,
    "startColumn": 78,
    "endLineNumber": 125,
    "endColumn": 78
}

Does this issue occur when all extensions are disabled?: Yes/No

[sean-mcmanus]

Thanks for reporting this. Yeah, it looks like an issue particular to the Mac clang 10.0 since I'm not seeing it with cl.exe/gcc or clang 3.9 (which I think corresponds to Mac clang 9).

[python152]

I tried the following the modification, setting a different compiler path (gcc@8 installed by homebrew), the error still shows up.

{
    "configurations": [
        {
            "name": "Mac",
            "includePath": [
                "${workspaceFolder}/**"
            ],
            "defines": [],
            "macFrameworkPath": [
                "/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/System/Library/Frameworks"
            ],
            "compilerPath": "/usr/local/bin/gcc-8",
            "configurationProvider": "vector-of-bool.cmake-tools"
        }
    ],
    "version": 4
}

[sean-mcmanus]

You have a configurationProvider set, which will use that to determine the includePath for system headers, ignoring the compilerPath. Setting your C_Cpp.loggingLevel to "Debug" should allow you to see what include paths are actually being used in the C/C++ output window (I'm not sure if homebrew gcc on Mac will use the clang libc++ header still). I'm not seeing this error with gcc-8 on Linux:

[sean-mcmanus]

I filed a bug with Visual Studio at https://developercommunity.visualstudio.com/content/problem/374666/c-intellisense-reports-incorrect-more-than-one-ope.html .

I got a simpler isolated repro:

template <class T> class TC;

// The bug doesn't repro when this declaration is omitted.
template <class T>
auto operator-(TC<T> x, TC<T> y) -> decltype(x.base() - y.base());

template <class T>
struct TC
{
    int base() { return 0; }
};

template <class T>
auto operator-(TC<T> x, TC<T> y) -> decltype(x.base() - y.base())
{
    return x.base() - y.base();
}

int main()
{
    TC<int*> i, j;
    return i - j; // error here.
}

[sean-mcmanus]

This incorrect IntelliSense error squiggle with clang 10 libraries should be fixed now with our latest Insiders release: https://github.com/Microsoft/vscode-cpptools/releases . If you're using VS Code Insiders or have http.proxySupport not set to "off", you might not get the 0.21.0-insiders2 update automatically with C_Cpp.updateChannel set to "Insiders".