Remove mem.rs line numbers from const-size_of-cycle.stderr

[dtolnay]

rust/src/test/ui/consts/const-size_of-cycle.stderr

Line 5 in 1558ae7

--> $SRC_DIR/libcore/mem.rs:323:14

It is not nice for this test to fail any time we insert a line in mem.rs, as happened in #53503. Please implement this test in a way that does not hardcode a line number.

Please also try to find standard library line numbers in other ui tests and scrub those in the same way.

As far as I can tell, the const-size_of-cycle.stderr file was newly added in #53196 so attn @davidtwco.

[dtolnay]

rg SRC_DIR/lib src turns up only one other case:

rust/src/test/ui/impl-trait/impl-generic-mismatch.stderr

Line 33 in 1558ae7

::: $SRC_DIR/libcore/hash/mod.rs:185:13

[eddyb]

We scrub line numbers on the left, I wonder if we should do it for all paths, always.
cc @nikomatsakis

[davidtwco]

@eddyb I think it could make sense to keep line numbers for paths like it is now - I think there could be an (admittedly rare) case where a change causes an error to be reported on an incorrect line and that wouldn't be spotted (although, the highlighted code from the error would need to be the same on both lines - which isn't impossible, just unlikely).

Either way, I'll put together a PR that normalizes these two cases for the time being.

[davidtwco]

Submitted #53558 that adds normalization for this case to compiletest as I think we wouldn't ever want to assert that line numbers from compiler source do not change in error messages.