Use c++14 to pass the verilator check

[Emin017]

When I update to verilator v5.022, the svsim test will fail (someone has already raised an issue). I found out this was because verilator added a check for the c++14 standard.

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Type of Improvement

• Bugfix

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Release Notes

Change ChiselSim to requires a C++14 compiler.

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[seldridge]

Generally seems fine to me. There shouldn't be an issue with requiring a compiler that supports C++14.

We haven't bumped the version of Tabby CAD OSS Suite in a while, so this likely hasn't cropped up. (We're using an older version of Verilator in CI.) We should probably do that, too, put that on latest, or add nightly/CD that tries to keep Tabby CAD up to date.

[jackkoenig]

We should merge this, but a longer term fix is we should probably make the arguments version-specific so that we can support some older Linux distros and Verilator versions out-of-the-box.

[jackkoenig]

I also wouldn't call this "No release notes", we do now require a compiler with C++14 support which should work for most, but lots of users in the hardware industry are on surprisingly old Linux distros.

[seldridge]

@jackkoenig: Can we backport this and/or get this onto a non-snapshot release? I think this may be necessary for newer Verilator. I'm thinking this (chipsalliance/chisel-template#127) is related.

[jackkoenig]

@seldridge sure, no reason not to release 6.2.0 (or 6.1.1?) with this.