ui test error output doesn't play nicely with "goto file" in vscode

[lcnr]

it seems like the source directory in the printout for ui tests uses "fake-test-src-base" rn, e.g.

---- [ui] tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs stdout ----

error: test compilation failed although it shouldn't!
status: exit status: 1
command: "/home/lcnr/rust6/build/x86_64-unknown-linux-gnu/stage1/bin/rustc" "/home/lcnr/rust6/tests/ui/traits/new-solver/prefer-param-env-on-ambiguity.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--remap-path-prefix=/home/lcnr/rust6/tests/ui=fake-test-src-base" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/home/lcnr/rust6/build/x86_64-unknown-linux-gnu/test/ui/traits/new-solver/prefer-param-env-on-ambiguity" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/home/lcnr/rust6/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/home/lcnr/rust6/build/x86_64-unknown-linux-gnu/test/ui/traits/new-solver/prefer-param-env-on-ambiguity/auxiliary" "-Ztrait-solver=next"
stdout: none
--- stderr -------------------------------
error[E0283]: type annotations needed: cannot satisfy `T: Foo<'a>`
  --> fake-test-src-base/traits/new-solver/prefer-param-env-on-ambiguity.rs:7:34
   |
LL | impl<'a, T: Bar<'a>> Foo<'a> for T {}
   |                                  ^
   |
   = note: cannot satisfy `T: Foo<'a>`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0283`.
------------------------------------------

this prevents ctrl+leftclick in vscode to take me directly to the relevant point in the source of the failing test.

it would be nice to somehowo keep the actual path in the output for ui tests and only normalize it when writing into the stderr file?

see https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/ui.20tests.20.22fake-test-src-base.22 for more details

[jyn514]

Note that we already print the real path in the "--- [ui] ... stdout ---" line at the top, but it would be nice to have this in addition so that line/column jumping works too.

[jyn514]

One possible workaround is to only pass remap-path-prefix in CI. I think it may also be possible to solve the problem on #105924 with a different mechanism entirely by stripping out the the directory with test normalization for UI tests involving closures?

https://rustc-dev-guide.rust-lang.org/tests/ui.html#normalization

[TimNN]

I think it may also be possible to solve the problem on #105924 with a different mechanism entirely by stripping out the the directory with test normalization for UI tests involving closures?

I think there are two reasons why this may be a suboptimal solution:

1. You'd still have to deal with the = note: the full name for the casted type has been written to ... showing up depending on the path length.

2. The difference between $DIR/fallback-closure-wrap.rs and fallback-closure-wrap.rs is that the $DIR version indicates that rustc has printed a full path, whereas for the non-$DIR version only a filename was printed. It may be useful / desirable to be able to distinguish the two cases in the output files.

[jyn514]

👍 makes sense - in that case the simplest fix is to gate remap-path-prefix on CiEnv::current() != None