Expand description
This pass is only used for UNIT TESTS related to incremental
compilation. It tests whether a particular .o file will be re-used
from a previous compilation or whether it must be regenerated.
The user adds annotations to the crate of the following form:
#![rustc_partition_reused(module="spike", cfg="rpass2")]
#![rustc_partition_codegened(module="spike-x", cfg="rpass2")]The first indicates (in the cfg rpass2) that spike.o will be
reused, the second that spike-x.o will be recreated. If these
annotations are inaccurate, errors are reported.
The reason that we use cfg=... and not #[cfg_attr] is so that
the HIR doesn’t change as a result of the annotations, which might
perturb the reuse results.
#![rustc_expected_cgu_reuse(module="spike", cfg="rpass2", kind="post-lto")]
allows for doing a more fine-grained check to see if pre- or post-lto data
was re-used.