add preliminary support for incremental compilation to rustbuild.py
This implements the integration described in #37929. It requires the use of a local nightly as your bootstrap compiler. The setup is described in `src/bootstrap/README.md`.
This does NOT implement the "copy stage0 libs to stage1" optimization described in #37929, just because that seems orthogonal to me.
In local testing, I do not yet see any incremental re-use when building rustc. I'm not sure why that is, more investigation needed.
(For these reasons, this is not marked as fixing the relevant issue.)
r? @alexcrichton -- I included one random cleanup (`Step::noop()`) that turned out to not be especially relevant. Feel free to tell me you liked it better the old way.
This not only avoids the small – and unnecessary – constant overhead for each compiler invocation,
but also helps somewhat by only having “correct” rustc processes to look for in `/proc/`.
This also makes the wrapper behave effectively as a regular exec wrapper its intended to be.
Currently libraries installed by rustbuild on OSX have an incorrect
`LC_ID_DYLIB` directive located in the dynamic libraries that are
installed. The directive we expect looks like:
@rpath/libstd.dylib
Which means that if you want to find that dynamic library you should
look at the dylib's other `@rpath` directives. Typically our `@rpath`
directives look like `@loader_path/../lib` for the compiler as that's
where the installed libraries will be located. Currently, though,
rustbuild produces dylibs with the directive that looks like:
/Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/build/x86_64-apple-darwin/stage1-std/x86_64-apple-darwin/release/deps/libstd-713ad88203512705.dylib
In other words, the build directory is encoded erroneously. The compiler
already [knows how] to change this directive, but it only passes that
argument when `-C rpath` is also passed. The rustbuild system, however,
explicitly [does not pass] this option explicitly and instead bakes its
own. This logic then also erroneously didn't pass `-Wl,-install_name`
like the compiler.
[knows how]: 4a008cccaa/src/librustc_trans/back/linker.rs (L210-L214)
[does not pass]: 4a008cccaa/src/bootstrap/bin/rustc.rs (L133-L158)
To fix this regression this patch introduces a new `-Z` flag, `-Z
osx-rpath-install-name` which basically just forces the compiler to take
the previous `-install_name` branch when creating a dynamic library.
Hopefully we can sort out a better rpath story in the future, but for
now this "hack" should suffice in getting our nightly builds back to the
same state as before.
Closes#38430
This commit enables by default passing the `-C debuginfo=1` argument to the
compiler for the stable, beta, and nightly release channels. A new configure
option was also added, `--enable-debuginfo-lines`, to enable this behavior in
developer builds as well.
Closes#36452
The organization in rustbuild was a little odd at the moment where the `lib.rs`
was quite small but the binary `main.rs` was much larger. Unfortunately as well
there was a `build/` directory with the implementation of the build system, but
this directory was ignored by GitHub on the file-search prompt which was a
little annoying.
This commit reorganizes rustbuild slightly where all the library files (the
build system) is located directly inside of `src/bootstrap` and all the binaries
now live in `src/bootstrap/bin` (they're small). Hopefully this should allow
GitHub to index and allow navigating all the files while maintaining a
relatively similar layout to the other libraries in `src/`.
