Converted Rust Test Case to DejaGnu

[MahadMuhammad]

A very simple PR to Investigate test case from https://github.com/rust-lang/rust/tree/master/tests/ui/anon-params. To convert this into equivalent Rust source file with dejagnu directives instead of ERROR directives

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gcc/testsuite/ChangeLog:

* rust/compile/anon-params-denied-2018.rs: New test.
* rust/compile/anon-params-deprecated.rs: New test.

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Details

Thanks to this email thread: https://patchwork.ozlabs.org/project/gcc/patch/20160922200546.GH7282@tucnak.redhat.com/. I was able to understand the relative line number. Otherwise, it would be difficult to stop dejagnu from shouting

[MahadMuhammad]

Additionally, there are some mismatches between rustc error output and gccrs error outputs. I also need to look into that.

[CohenArthur]

I notice that you've adapted the error messages to be the ones output by gccrs. I think our strategy for now should be the following:

1. If there is an error code, then take it and copy it for the dg-error message
2. otherwise, just add an empty dg-error

we don't want the error messages to match exactly, but we do want the error codes to match exactly. in the future, we can think about doing something like a map from Rust error messages to gccrs error messages, but that should come later :)

[CohenArthur]

are those TODO because gccrs doesn't output an error here?

[MahadMuhammad]

Yes, gccrs doesn't omits output here (see line 16 here: https://godbolt.org/z/MGdE35PPT) maybe due to excess errors. However, it emits output for fn definition, see here: https://godbolt.org/z/WEr89c5xq.

[tschwinge]

I suggest we eventually put these "external" test cases into a separate directory, which then also contains some README file describing where they're coming from, and which exact upstream revision they're based on.

You may extend the glob in gcc/testsuite/rust/compile/compile.exp to look into that new directory, too, or have a separate *.exp file in the new directory, if that's maybe useful for other reasons (like, to specify default compilation flags to dg-runtest). See, for example, gcc/testsuite/gcc.dg/gomp/gomp.exp search two directories by default, and specify -fopenmp by default.

[CohenArthur]

yeah, I believe the best thing would be to go with a separate .exp file because we might eventually want to tweak it as you said Thomas. so I would just copy the compile.exp file so that it works for that new directory

[MahadMuhammad]

Sure. I'll work on that. Also, the test cases in this PR have very different output on rustc (see this: https://godbolt.org/z/MGdE35PPT). So, should I update this PR with only with the error codes of rustc?