And implement addons as necessary.
There are many more makers to be moved, and I'm not completely satisfied with this (due to the ease of making a mistake in the AST structure, and slightly less but also because of the need to remember whitespaces), but this is already enough to see how this will look like.
Avoid ICE in borrowck
Provide a fallback in `best_blame_constraint` when `find_constraint_paths_between_regions` doesn't have a result. This code is due a rework to avoid the letf-over `unwrap()`, but avoids the ICE caused by the repro.
Fix#133252.
Unify fs::copy and io::copy on Linux
Currently, `fs::copy` first tries a regular file copy (via copy_file_range) and then falls back to userspace read/write copying. We should use `io::copy` instead as it tries copy_file_range, sendfile, and splice before falling back to userspace copying. This was discovered here: https://github.com/SUPERCILEX/fuc/issues/40
Perf impact: `fs::copy` will now have two additional statx calls to decide which syscall to use. I wonder if we should get rid of the statx calls and only continue down the next fallback when the relevant syscalls say the FD isn't supported.
fix default-backtrace-ice test
when running `tests/ui/panics/default-backtrace-ice.rs locally it gave this error:
```
failures:
---- [ui] tests/ui/panics/default-backtrace-ice.rs stdout ----
Saved the actual stderr to "/home/jyn/src/rust3/build/x86_64-unknown-linux-gnu/test/ui/panics/default-backtrace-ice/default-backtrace-ice.stderr"
diff of stderr:
7
8 aborting due to `-Z treat-err-as-bug=1`
9 stack backtrace:
- (end_short_backtrace)
- (begin_short_backtrace)
- (end_short_backtrace)
- (begin_short_backtrace)
+ [... omitted 22 frames ...]
+
```
(note that you must *not* use --bless; we previously did not have an error annotation to verify it was a full backtrace instead of a short backtrace.)
this is a regression from setting RUST_BACKTRACE=1 by default in https://github.com/rust-lang/rust/pull/134743. we need to turn off the new behavior when running UI tests so that they reflect our dist compiler. normally that's done by checking `sess.unstable_opts.ui_testing`, but this happens extremely early in the compiler before we've expanded arg files. do an extremely simple hack that doesn't work in all cases - we don't need it to work in all cases, only when running UI tests.
cc https://github.com/rust-lang/rust/pull/129658#issuecomment-2561988081
r? `@jieyouxu`
