This commit removes all infrastructure from the repository for our so-called
snapshots to instead bootstrap the compiler from stable releases. Bootstrapping
from a previously stable release is a long-desired feature of distros because
they're not fans of downloading binary stage0 blobs from us. Additionally, this
makes our own CI easier as we can decommission all of the snapshot builders and
start having a regular cadence to when we update the stage0 compiler.
A new `src/etc/get-stage0.py` script was added which shares some code with
`src/bootstrap/bootstrap.py` to read a new file, `src/stage0.txt`, which lists
the current stage0 compiler as well as cargo that we bootstrap from. This script
will download the relevant `rustc` package an unpack it into `$target/stage0` as
we do today.
One problem of bootstrapping from stable releases is that we're not able to
compile unstable code (e.g. all the `#![feature]` directives in libcore/libstd).
To overcome this we employ two strategies:
* The bootstrap key of the previous compiler is hardcoded into `src/stage0.txt`
(enabled as a result of #32731) and exported by the build system. This enables
nightly features in the compiler we download.
* The standard library and compiler are pinned to a specific stage0, which
doesn't change, so we're guaranteed that we'll continue compiling as we start
from a known fixed source.
The process for making a release will also need to be tweaked now to continue to
cadence of bootstrapping from the previous release. This process looks like:
1. Merge `beta` to `stable`
2. Produce a new stable compiler.
3. Change `master` to bootstrap from this new stable compiler.
4. Merge `master` to `beta`
5. Produce a new beta compiler
6. Change `master` to bootstrap from this new beta compiler.
Step 3 above should involve very few changes as `master` was previously
bootstrapping from `beta` which is the same as `stable` at that point in time.
Step 6, however, is where we benefit from removing lots of `#[cfg(stage0)]` and
get to use new features. This also shouldn't slow the release too much as steps
1-5 requires little work other than waiting and step 6 just needs to happen at
some point during a release cycle, it's not time sensitive.
Closes#29555Closes#29557
In #26252 support was added to have prettier paths printed out on failure by not
passing the full path to the source file to the compiler, but instead just a
small relative path. To preserve this relative path across configurations, the
`SREL` variable was used for reconfiguring, but if `SREL` is empty then it will
attempt to run the command `configure` which is distinct from running
`./configure` (e.g. doesn't run the local script).
This commit modifies the `SREL` value to re-run the configure script by setting
it to `./` in the case where `SREL` is empty.
The path we pass to rustc will be visible in panic messages and
backtraces: they will be user visible!
Avoid junk in these paths by passing relative paths to rustc.
For most advanced users, `libcore` or `libstd` in the path will be
a clue to the location -- inside our code, not theirs.
Store both the relative path to the source as well as the absolute.
Use the relative path where it matters, compiling the main crates,
instead of changing all of the build process to cope with relative
paths.
Example output after this patch:
```
$ ./testunwrap
thread '<main>' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:362
$ RUST_BACKTRACE=1 ./testunwrap
thread '<main>' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/option.rs:362
stack backtrace:
1: 0x7ff59c1e9956 - sys::backtrace::write::h67a542fd2b201576des
at ../src/libstd/sys/unix/backtrace.rs:158
2: 0x7ff59c1ed5b6 - panicking::on_panic::h3d21c41cdd5c12d41Xw
at ../src/libstd/panicking.rs:58
3: 0x7ff59c1e7b6e - rt::unwind::begin_unwind_inner::h9f3a5440cebb8baeLDw
at ../src/libstd/rt/unwind/mod.rs:273
4: 0x7ff59c1e7f84 - rt::unwind::begin_unwind_fmt::h4fe8a903e0c296b0RCw
at ../src/libstd/rt/unwind/mod.rs:212
5: 0x7ff59c1eced7 - rust_begin_unwind
6: 0x7ff59c22c11a - panicking::panic_fmt::h00b0cd49c98a9220i5B
at ../src/libcore/panicking.rs:64
7: 0x7ff59c22b9e0 - panicking::panic::hf549420c0ee03339P3B
at ../src/libcore/panicking.rs:45
8: 0x7ff59c1e621d - option::Option<T>::unwrap::h501963526474862829
9: 0x7ff59c1e61b1 - main::hb5c91ce92347d1e6eaa
10: 0x7ff59c1f1c18 - rust_try_inner
11: 0x7ff59c1f1c05 - rust_try
12: 0x7ff59c1ef374 - rt::lang_start::h7e51e19c6677cffe5Sw
at ../src/libstd/rt/unwind/mod.rs:147
at ../src/libstd/rt/unwind/mod.rs:130
at ../src/libstd/rt/mod.rs:128
13: 0x7ff59c1e628e - main
14: 0x7ff59b3f6b44 - __libc_start_main
15: 0x7ff59c1e6078 - <unknown>
16: 0x0 - <unknown>
```
This commit removes the libuv and gyp submodules, as well as all build
infrastructure related to them.
For more context, see the [runtime removal
RFC](https://github.com/rust-lang/rfcs/pull/230)
[breaking-change]
Because the build system treats Makefile.in and the .mk files slightly
differently (.in is copied, .mk are included), this makes the system
more uniform. Fewer build system changes will require a complete
reconfigure.
