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"fpclassify': ambiguous call to overloaded function

I have a very similar problem to this one: How to resolve "fpclassify': ambiguous call to overloaded function

I have a large project with about 100 cpp-files and 100 header-files that work fine in Codeblocks using GNU GCC compiler, but I want to migrate the project to VS19. It seems to work fine except for one error: "fpclassify': ambiguous call to overloaded function

The error list in VS19 tells me it is located in corecrt_math.h on a return value at line 415:

template <class _Ty>
_Check_return_ inline bool isnan(_In_ _Ty _X) throw()
{
    return fpclassify(_X) == FP_NAN;
}

When looking into my code I see that I use std::isna in 13 files, 24 locations (the error list does not refer to these places at all). However, unlike the problem that I linked to above, I do not see that I check if an int is na anywhere. Instead I have cases like this:

if (std::isnan(static_cast<double> (min)) && std::isnan(static_cast<double> (max)))
    simulation_error("Error: No limits");

Where minand max are defined as const double & min = NAN and const double & max = NAN (min and max are set in the constructor).

Do you have any idea on how to find the error and how to solve it? I tried many hours yesterday - without any success.

Edit:

Full error message below:

1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\corecrt_math.h(415,1): error C2668: 'fpclassify': ambiguous call to overloaded function
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\corecrt_math.h(300,31): message : could be 'int fpclassify(long double) noexcept'
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\corecrt_math.h(295,31): message : or       'int fpclassify(double) noexcept'
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\corecrt_math.h(290,31): message : or       'int fpclassify(float) noexcept'
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\ucrt\corecrt_math.h(415,1): message : while trying to match the argument list '(_Ty)'
1>        with
1>        [
1>            _Ty=bool
1>        ]
1>C:\Users\Name\Documents\C++\Project name\Project name\src\module.cpp(668): message : see reference to function template instantiation 'bool isnan<bool>(_Ty) noexcept' being compiled
1>        with
1>        [
1>            _Ty=bool
1>        ]

Which refers to:

std::vector<double> stoprule_rel;,

if (!(std::isnan(static_cast<double> (stoprule_rel[i])
Solution

  • The error message like fpclassify': ambiguous call to overloaded function is always accompanied by notes. For example, for a simple program

    #include <cmath>
int main() {
    std::isnan(5);
}

    VS complains:

    corecrt_math.h(415): error C2668: 'fpclassify': ambiguous call to overloaded function
corecrt_math.h(300): note: could be 'int fpclassify(long double) throw()'
corecrt_math.h(295): note: or       'int fpclassify(double) throw()'
corecrt_math.h(290): note: or       'int fpclassify(float) throw()'
corecrt_math.h(415): note: while trying to match the argument list '(_Ty)'
        with [ _Ty=int ]
<source>(3): note: see reference to function template instantiation 'bool isnan<int>(_Ty) throw()' being compiled
        with [ _Ty=int ]

    From these notes we can infer that _Ty is int and that std::nan was called on the line 3 of our source code. Take a look at the full compiler output for your compilation, it will tell you the exact place in your code where the error is triggered.