scotch: add oneAPI compiler flags that disable optimizations that alter mathematical results

[rickgrubin-noaa]

Add oneAPI compiler flags that disable optimizations that alter mathematical results

For Intel OneAPI C and Fortran compilers, set the following flags for the scotch package recipe:

• -fp-model=precise
  • Disables value-unsafe floating-point optimizations to ensure consistent numerical accuracy; results are predictable and reproducible across compiler versions.
• -fp-speculation=safe
  • Disables speculation if there is a chance it might cause a floating-point exception.

These are set for CMAKE_{C,Fortran}_FLAGS to cover all build configuration types (Debug, Release, RelWithDebInfo, MinSizeRel).

Also changes the build_system() conditional so that cmake is the gated default for v7: and makefile is gated to older versions, and constrain oneAPI builds to use cmake.

Fixes: JCSDA/spack-stack#2075

Testing

Build test envs on hercules and orion with this PR's code changes; results are satisfactory, see here; @gspetro-NOAA has successfully run full regression tests.

A PR for authoritative spack-packages will also be created in the event that the PR for scotch either isn't accepted or is not merged prior to the next spack-stack release

[climbfuji]

If I understand correctly, this means that for versions 6 and earlier, both cmake and makefile are an option, and the default is cmake?

The original line 47 to me reads like cmake available from version 7 and makefile available for all versions, suggesting that the cmake build wasn't available for versions 6 and earlier?

If I am right (probably not ...) and our goal is to switch from makefile for version 6 to cmake for version 7, then this is sufficient?

build_system("make", when="@:6"))
build_system("cmake", when="@7:"))

The issue with that is that line 48 effectively precludes building scotch@:6 with oneapi. But maybe that's ok. After all, we weren't able to build scotch with oneapi until recently.

@AlexanderRichert-NOAA thoughts?

[rickgrubin-noaa]

If I understand correctly, this means that for versions 6 and earlier, both cmake and makefile are an option, and the default is cmake?

The original line 47 to me reads like cmake available from version 7 and makefile available for all versions, suggesting that the cmake build wasn't available for versions 6 and earlier?

7: -- only cmake for build system
:6 -- cmake or makefile, default cmake

based on your comment from JCSDA/spack-stack#2075

If I am right (probably not ...) and our goal is to switch from makefile for version 6 to cmake for version 7, then this is sufficient?

build_system("make", when="@:6"))
build_system("cmake", when="@7:"))

I was trying to allow cmake or makefile for :6 but restrict to cmake for 7: -- if it's best to only build with makefile for :6, your suggestion does that. I am certainly agnostic about it.

The issue with that is that line 48 effectively precludes building scotch@:6 with oneapi. But maybe that's ok. After all, we weren't able to build scotch with oneapi until recently.

That is the point of line 48.

[climbfuji]

Understood. git diff can be so confusing. Thanks for the clarification.