Correctly namespace more math functions.

[kevingranade]

Summary

SUMMARY: None

Purpose of change

As outlined in #39388 these non-standard invocations of math functions are problematic.

Describe the solution

Stick em in the std namespace.

Testing

Needs to build, and I expect lgtm to agree it cleared up a bunch of alerts.

Additional context

I realized something else, implementations are allowed to put e.g. pow() in the global namespace in , but they are also allowed not to, which would fail our build on such a system.

[kevingranade]

Weird roadbump, GCC standard library does not export sqrtf() into the std namespace.
https://stackoverflow.com/questions/43183252/cmake-sqrtf-is-not-a-member-of-std

[jbytheway]

Weird roadbump, GCC standard library does not export sqrtf() into the std namespace.
https://stackoverflow.com/questions/43183252/cmake-sqrtf-is-not-a-member-of-std

Yeah, I remember running into this issue when I looked into some related warnings. I didn't come up with a good answer.

[kevingranade]

AFAICT the answer is either just don't use it or export it into std ourselves.
I really don't like the latter because it essentially means we have to carry around our own cmath wrapper and use it everywhere.

[jbytheway]

Agreed. I think just don't use it. It will lead to more -Wdouble-promotion errors errors if we ever turn on that particular warning, but that's life.

[kevingranade]

Turns out same story with powf() >_<

[lgtm-com]

This pull request fixes 80 alerts when merging 30960c2 into a664636 - view on LGTM.com

fixed alerts:

• 80 for Use of c-style math functions

[lgtm-com]

This pull request fixes 79 alerts when merging 7b588d3 into 388be3b - view on LGTM.com

fixed alerts:

• 79 for Use of c-style math functions

[lgtm-com]

This pull request fixes 79 alerts when merging fa2cd6b into 72a6afa - view on LGTM.com

fixed alerts:

• 79 for Use of c-style math functions