`-Zunpretty=expanded` does not emit `dep-info` anymore (1.68 -> 1.69)

[ojeda]

rm -f x.d && echo 'fn main() {}' |
    RUSTC_BOOTSTRAP=1 rustup run 1.68.2 rustc - --emit=dep-info=x.d -Zunpretty=expanded >/dev/null &&
    cat x.d
x.d: 

rm -f x.d && echo 'fn main() {}' |
    RUSTC_BOOTSTRAP=1 rustup run 1.69.0 rustc - --emit=dep-info=x.d -Zunpretty=expanded >/dev/null &&
    cat x.d
cat: x.d: No such file or directory

Related: #93201 (i.e. having expanded as an actual --emit would be nice).

We use -Zunpretty=expanded in the kernel to provide the expanded output in .rsi outputs/targets. The dependency information is not critical, but the change made our Make target fail (so we need a change on the kernel side), and it would be nice nevertheless to have the dependency information (assuming it is accurate), e.g. we also use it for similar outputs like .ll and .s.

[apiraino]

Bisection seems to lead to commit d7948c8 but I am not sure / cant say if really related. The mentioned issue #93201 was opened before that commit was merged 🤔 @oli-obk @petrochenkov wdy?

[oli-obk]

This looks like another symptom of #93201

We'll likely keep regressing this by accident without a test. I don't know why #93201 was fixed between when it was reported and 1.68

[ojeda]

Thanks for fixing this @Urgau!