`--emit=dep-info` + `-Zunpretty=expanded` emits output

[ojeda]

In 1.58, running:

echo 'fn main() {}' | rustc --emit=dep-info,obj,metadata -

will generate .d, .o and .rmeta files, as expected. However, running with -Zunpretty=expanded:

echo 'fn main() {}' | rustc --emit=dep-info,obj,metadata -Zunpretty=expanded -

will generate the .d only. I would have expected that rustc does not generate any file, or that it generates all of them, or that it complains if --emit and -Zunpretty are supposed to be incompatible with each other. Should users avoid mixing both at the moment?

(I assume that, eventually, --emit=dep-info,expanded would give the dependency information about the expanded output file like it does for the others; which is fine)

It also happens with e.g. -Zunpretty=hir, but not with -Zunpretty=normal or -Zunpretty=ast-tree; thus it looks like a consequence of which passes are executed in the compiler.

Possibly related: #60857.

[ojeda]

For 1.68, the second command, i.e.

echo 'fn main() {}' | rustc --emit=dep-info,obj,metadata -Zunpretty=expanded -

still generated the .d file, but 1.71 does not anymore. I am not sure if that is the intended behavior or not.

Cc'ing @Urgau in case they know or are interested since #114476 just got merged.

[fmease]

but 1.71 does not anymore

1.77 (nightly) generates rustc_out.d yet again (?).