The old struct tail functions did not deal with `<T as Trait>::A` and `impl
Trait`, at least not explicitly. (We didn't notice this bug before because it
is only exposed when the tail (post deep normalization) is not `Sized`, so it
was a rare case to deal with.)
For post type-checking (i.e. during codegen), there is now
`struct_tail_erasing_lifetimes` and `struct_lockstep_tails_erasing_lifetimes`,
which each take an additional `ParamEnv` argument to drive normalization.
For pre type-checking cases where normalization is not needed, there is
`struct_tail_without_normalization`. (Currently, the only instance of this is
`Expectation::rvalue_hint`.)
All of these new entrypoints work by calling out to common helper routines.
The helpers are parameterized over a closure that handles the normalization.
This is useful for getting the total compilation time at the end.
To do this, the patch changes `print_time_passes_entry` to not increment
the depth, which means that `print_time_passes_entry_internal` is no
longer needed.
This commit separates metadata encoding (`tcx.encode_metadata`) from the
creation of the metadata module (which is now handled by
`write_compressed_metadata`, formerly `write_metadata`).
The metadata encoding now occurs slightly earlier in the pipeline, at
the very start of code generation within `start_codegen`.
Metadata *writing* still occurs near the end of compilation; that will
be moved forward in subsequent commits.
This commit updates the LLVM branch to the rebased version of the
upstream release/8.x branch. This includes a wasm patch which means that
the `rewrite_imports` pass in rustc is no longer needed (yay!) and we
can instead rely on `wasm-import-module`, an attribute we're already
emitting, to take care of all the work.
`codegen_allocator` and `write_metadata` mutate the underlying LLVM module. As
such, it makes sense for these two functions to receive a mutable reference to
the module (as opposed to an immutable one).
Cosmetic improvements to doc comments
This has been factored out from https://github.com/rust-lang/rust/pull/58036 to only include changes to documentation comments (throughout the rustc codebase).
r? @steveklabnik
Once you're happy with this, maybe we could get it through with r=1, so it doesn't constantly get invalidated? (I'm not sure this will be an issue, but just in case...) Anyway, thanks for your advice so far!
