std::lerp is missing Arithmetic overloads

[Quuxplusone]

Bugzilla Link	PR51464
Status	NEW
Importance	P enhancement
Reported by	Kostiantyn Pesteriev (konstantinua00@gmail.com)
Reported on	2021-08-12 15:00:58 -0700
Last modified on	2021-08-13 13:56:43 -0700
Version	12.0
Hardware	PC Linux
CC	llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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According to C++20 standard paragraph 20.8.1.2 ( [cmath.syn] ), std::lerp is
not an exception to expansion of acceptable parameters to integral and mixed
floating point types.
I.e. overload 4) from https://en.cppreference.com/w/cpp/numeric/lerp is missing.

Example code (compile with -std=c++20):

#include<cmath>

int main()
{
    std::lerp(int{},int{},int{});
    std::lerp(float{}, double{}, (long double)0);
}

https://godbolt.org/z/vboY4aoE9

Current behaviour:
Does not compile with: "error: call to 'lerp' is ambiguous" (twice)

Expected behaviour:
Compilation with no issues.

[Quuxplusone]

I apologize, I did not know that clang on godbolt by default uses libstdc++

Example code is the same, but compile with -std=c++20 *and* -stdlib=libc++
https://godbolt.org/z/c3PqWez9x