Added warning around code with reference to uninit bytes
Officially, uninitialized integers, and therefore, Rust references to them are _invalid_ (note that this may evolve into official defined behavior (_c.f._, https://github.com/rust-lang/unsafe-code-guidelines/issues/71)).
However, `::std` uses references to uninitialized integers when working with the `Read::initializer` feature (#42788), since it relies on this unstably having defined behavior with the current implementation of the compiler (IIUC).
Hence the comment to disincentivize people from using this pattern outside the standard library.
Update xLTO compatibility table in rustc book.
This is a combination known to work reliable when building Firefox on all the major platforms.
r? @alexcrichton
Add a `Place::is_indirect` method to determine whether a `Place` contains a `Deref` projection
Working on #63860 requires tracking some property about each local. This requires differentiating `Place`s like `x` and `x.field[index]` from ones like `*x` and `*x.field`, since the first two will always access the same region of memory as `x` while the latter two may access any region of memory. This functionality is duplicated in various places across the compiler. This PR adds a helper method to `Place` which determines whether that `Place` has a `Deref` projection at any point and changes some existing code to use the new method.
I've not converted `qualify_consts.rs` to use the new method, since it's not a trivial conversion and it will get replaced anyway by #63860. There may be other potential uses besides the two I change in this PR.
r? @oli-obk
Rustbuild usually writes the LLVM submodule commit in a stamp file, so
we can avoid rebuilding it unnecessarily. However, for builds from a
source tarball (non-git), we were assuming a rebuild is always needed.
This can cause a lot of extra work if any environment like `CFLAGS`
changed between steps like build and install, which are often separate
in distro builds.
Now we also write an empty stamp file if the git commit is unknown, and
its presence is trusted to indicate that no rebuild is needed. An info
message reports that this is happening, along with the stamp file path
that can be deleted to force a rebuild anyway.
Allow checking of run-pass execution output in compiletest
Closes#63751
Adds a `check-run-results` flag to compiletest headers, which if enabled checks the output of the execution of a run-pass test's binary against expected output.
They are only used by rustc_lexer, and are not needed elsewhere.
So we move the relevant definitions into rustc_lexer (while the actual
unicode data comes from the unicode-xid crate) and make the rest of
the compiler use it.
Add Result::cloned{,_err} and Result::copied{,_err}
This is a little nice addition to `Result`.
1. I'm not sure how useful are `cloned_err` and `copied_err`, but for the sake of completeness they are here.
2. Naming is similar to `map`/`map_err`. I thought about naming `cloned` as `cloned_ok` and add another method called `cloned` that clones both Ok and Err, but `cloned_ok` should be more prevalent than `cloned_both`.
- var_starts_path
- parent
- initialized_at
- moved_out_at
This also switches to the intended emission of `var_drop_used` fact emission,
where that fact is always emitted on a drop-use of a variable, regardless of its
initialization status, as Polonius now handles that.
And remove the `unsafe` blocks, they're not necessary.
Also rewrite `InternedString::{with,with2}` to use the new functions.
Finally, add some comments about the speed of the
`as_str()`/`as_interned_str()` functions.
