An 'asm' declaration is not allowed here

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So I have this code here, which does not let me compile my dll, It just returns the error above.

void Math::AngleVectors(const Vector &angles, Vector *forward, Vector *right, Vector *up)
{
    auto SinCos = [](float flRadians, float* pflSine, float* pflCosine)
    {

        __asm
        {
            fld DWORD PTR[flRadians]
            fsincos
            mov edx, DWORD PTR[pflCosine]
            mov eax, DWORD PTR[pflSine]
            fstp DWORD PTR[edx]
            fstp DWORD PTR[eax]
        } // here it says the error "an 'asm' declaration is not allowed here"
    };
[...]
}

I do not know how to solve this, does anyone know what's wrong here?

I am targeting x86

visual-studio-2019 c++
1 Answers

Unfortunately, you can't do what you're trying to do. Due to security concerns, inline assembly isn't supported inside a lambda in Visual Studio 2019:

https://docs.microsoft.com/en-us/cpp/overview/cpp-conformance-improvements?view=msvc-160#inline-assembly-code-isnt-supported-in-a-lambda-expression

Paraphrasing the answer (it's detailed), you must put the asm in a named function and have the lambda call that:


void SinCosAsm(float flRadians, float* pflSine, float* pflCosine) {
    __asm
    {
        fld DWORD PTR[flRadians]
        fsincos
        mov edx, DWORD PTR[pflCosine]
        mov eax, DWORD PTR[pflSine]
        fstp DWORD PTR[edx]
        fstp DWORD PTR[eax]
    }
    //...
}

void Math::AngleVectors(const Vector &angles, Vector *forward, Vector *right, Vector *up)
{
    auto SinCos = [](float flRadians, float* pflSine, float* pflCosine)
    {
        SinCosAsm(flRadians, pflSine, pflCosine);
    };
[...]
}
user_4211780
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