fix: early return for module file error in AST parsing

[0xllx0]

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Converts an assert into an early return during AST parsing.

Resolves: #4145

[0xllx0]

Not sure on the exact decorators needed here, or if this test should go into the xfail directory. The test is expected to fail compilation, just with an error message instead of an ICE.

[powerboat9]

grep for dg-error in the testsuite directory -- that should give you some nice examples for expecting error messages

[CohenArthur]

one tiny nitpick but the changes are really good, thank you for the work!

[philberty]

You need to fixup the regressions here those tests probably emit a new error now and they need updated accordingly

[0xllx0]

You need to fixup the regressions here those tests probably emit a new error now and they need updated accordingly

I rebased on the latest master (32ce955), and didn't get a failing test for the gcc/testsuite/rust/compile/issue-4145.rs test. Is there something specific where you are noticing regressions? Can you please provide reproduction steps so I can work on resolving the issue?

[powerboat9]

I think .-1 should be .1, if you want to catch an error on the next line instead of the previous line

[0xllx0]

Thanks, I changed it to .+1, and changed xfail to target since the compiler successfully returns an error (opposed to an ICE). Please let me know if that logic makes sense to you.

[P-E-P]

I rebased on the latest master (32ce955), and didn't get a failing test for the gcc/testsuite/rust/compile/issue-4145.rs test. Is there something specific where you are noticing regressions? Can you please provide reproduction steps so I can work on resolving the issue?

I can't remember the state of that PR when you first submitted it. This message seems to be out of date (there are multiple tests that are not passing anymore). Do you struggle with it ? Do you need some help ?

You probably need more constraints over your condition. Try executing the test using GDB to understand why it emits an error. Note that the tests may also have a slight chance of being wrong, even though I doubt it.

[0xllx0]

Do you struggle with it ? Do you need some help ?

I don't know enough at this point about the internals of gccrs to determine exactly why the early return is breaking the other tests. The test for issue-4145.rs passes, but obviously the other tests break.

Not sure what the best way forward is.

You probably need more constraints over your condition.

Possibly, but I currently lack the appropriate context for what the test condition should be that captures the motivating edge-case, and doesn't break the rest of the test suite. It will take me some time to get more familiar with the surrounding code.

Try executing the test using GDB to understand why it emits an error. Note that the tests may also have a slight chance of being wrong, even though I doubt it.

Thanks, that will probably help trace the relevant code paths.