[gpderetta]

You can set fast math (or a subset of it) on a translation unit basis.

[tialaramex]

Because the language works by textual inclusion and so a "translation unit" isn't really just your code this is much more likely to result in nasty surprises, up to and including ODR violations.

[gpderetta]

Yes, if you try hard enough I'm sure you can find ways to screw up.

From a practical point of view it is fine.

[pdw]

That's not really true. If you link a shared library that was compiled with -ffast-math, that will affect the entire program. https://moyix.blogspot.com/2022/09/someones-been-messing-wit...

[gpderetta]

To enable this "feature" I believe you have to specify fast math while linking the .so, it is not enough to do it when compiling.

It had also been fixed recent GCC versions.

[cozzyd]

Or even on a per function basis, at least with gcc (no clue about clang...)

[gpderetta]

In principle yes, you can use Attribute optimize, but I wouldn't rely on it. Too many bugs open against it.

[cozzyd]

It's worked for me in the past but maybe I got lucky.