tree 6d355600bd8476b66da2a8752ea878d0abfea915
parent dc685a2b72b24234ba5cbc821375c3d2ac4f0409
author Takuto Ikuta <tikuta@google.com> 1790724533 +0900
committer gn-scoped@luci-project-accounts.iam.gserviceaccount.com <gn-scoped@luci-project-accounts.iam.gserviceaccount.com> 1790752818 -0700

rust: Don't make rlibs depend on non-Rust link inputs

rustc does not invoke a linker when building an rlib, so non-Rust native
dependencies (object files of source_sets, static libraries and shared
libraries) are not used when compiling it. Since RUST_LIBRARY is not
final, these dependencies are already propagated as inherited libraries
to the final target that links the rlib.

However, NinjaRustBinaryTargetWriter added them to the rlib's rustc
command line (as -Clink-arg=...) and to its implicit ninja dependencies.
This made compiling an rlib wait for C/C++ code to be compiled, archived
and linked. For example, in a Chromium component build, compiling an
rlib depending on a C++ component waited for its shared library (and
those of its dependencies) to be linked, which put rlib compilation
after long chains of shared library links on the critical path.

Stop adding non-Rust link inputs to rlibs. Final targets still get them
through inherited libraries, as tested in NonRustDeps.

Bug: 563098656
Change-Id: Id5a80c39a44a4e347e8ad64505efe1e686171517
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/27000
Reviewed-by: David Turner <digit@google.com>
Commit-Queue: David Turner <digit@google.com>
Reviewed-by: Matt Stark <msta@google.com>