rustc --print file-names wrongly prints .rlib for --emit=metadata #54852
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A-driver
Area: rustc_driver that ties everything together into the `rustc` compiler
C-bug
Category: This is a bug.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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jonas-schievink
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A-driver
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cargo nightly will now invoke rustc with |
emilio
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Feb 3, 2020
This fixes cargo check in mozilla-central. The issue is that rustc --print file-names emits a somewhat poor approximation of what's actually going to be emitted. So for a staticlib crate, it will also print the staticlib file, which is not great. See https://bugzilla.mozilla.org/show_bug.cgi?id=1612855#c2 for a more straight-forward explanation of the failure case. Sccache would try to find the library and fail, erroring as a consequence. Pile up on the existing workaround for rmeta files not showing up (rust-lang/rust#54852) by removing files that are not metadata when we only request metadata. rust-lang/rust#68799 contains a rust-side fix that would also fix this.
froydnj
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Feb 3, 2020
This fixes cargo check in mozilla-central. The issue is that rustc --print file-names emits a somewhat poor approximation of what's actually going to be emitted. So for a staticlib crate, it will also print the staticlib file, which is not great. See https://bugzilla.mozilla.org/show_bug.cgi?id=1612855#c2 for a more straight-forward explanation of the failure case. Sccache would try to find the library and fail, erroring as a consequence. Pile up on the existing workaround for rmeta files not showing up (rust-lang/rust#54852) by removing files that are not metadata when we only request metadata. rust-lang/rust#68799 contains a rust-side fix that would also fix this.
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Triage: It seems to me as if
Note that it does not claim to print the name of the metadata file. |
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For sccache to cache rustc builds it uses
rustc --print file-namesto figure out which files get emitted so it cache them for later. For--emit metadatabuilds it appears thatrustcprints that it would emit a.rlibfile which seems to be false, only.rmetafiles get emitted.Trying to find out where this happens but so far no luck (it might actually be correct behavior and the fix should be in sccache).
See mozilla/sccache#301 (comment)
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