See #29864
This has been replaced by `#[feature(marker_trait_attr)]`
A few notes:
* Due to PR #68057 not yet being in the bootstrap compiler, it's
necessary to continue using `#![feature(overlapping_marker_traits)]`
under `#[cfg(bootstrap)]` to work around type inference issues.
* I've updated tests that used `overlapping_marker_traits` to now use
`marker_trait_attr` where applicable
The test `src/test/ui/overlap-marker-trait.rs` doesn't make any sense
now that `overlapping_marker_traits`, so I removed it.
The test `src/test/ui/traits/overlap-permitted-for-marker-traits-neg.rs`
now fails, since it's no longer possible to have multiple overlapping
negative impls of `Send`. I believe that this is the behavior we want
(assuming that `Send` is not going to become a `#[marker]` trait, so I
renamed the test to `overlap-permitted-for-marker-traits-neg`
build-std compatible sanitizer support
### Motivation
When using `-Z sanitizer=*` feature it is essential that both user code and
standard library is instrumented. Otherwise the utility of sanitizer will be
limited, or its use will be impractical like in the case of memory sanitizer.
The recently introduced cargo feature build-std makes it possible to rebuild
standard library with arbitrary rustc flags. Unfortunately, those changes alone
do not make it easy to rebuild standard library with sanitizers, since runtimes
are dependencies of std that have to be build in specific environment,
generally not available outside rustbuild process. Additionally rebuilding them
requires presence of llvm-config and compiler-rt sources.
The goal of changes proposed here is to make it possible to avoid rebuilding
sanitizer runtimes when rebuilding the std, thus making it possible to
instrument standard library for use with sanitizer with simple, although
verbose command:
```
env CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS=-Zsanitizer=thread cargo test -Zbuild-std --target x86_64-unknown-linux-gnu
```
### Implementation
* Sanitizer runtimes are no long packed into crates. Instead, libraries build
from compiler-rt are used as is, after renaming them into `librusc_rt.*`.
* rustc obtains runtimes from target libdir for default sysroot, so that
they are not required in custom build sysroots created with build-std.
* The runtimes are only linked-in into executables to address issue #64629.
(in previous design it was hard to avoid linking runtimes into static
libraries produced by rustc as demonstrated by sanitizer-staticlib-link
test, which still passes despite changes made in #64780).
cc @kennytm, @japaric, @firstyear, @choller
Enable `loop` and `while` in constants behind a feature flag
This PR is an initial implementation of #52000. It adds a `const_loop` feature gate, which allows `while` and `loop` expressions through both HIR and MIR const-checkers if enabled. `for` expressions remain forbidden by the HIR const-checker, since they desugar to a call to `IntoIterator::into_iter`, which will be rejected anyways.
`while` loops also require [`#![feature(const_if_match)]`](https://github.com/rust-lang/rust/pull/66507), since they have a conditional built into them. The diagnostics from the HIR const checker will suggest this to the user.
r? @oli-obk
cc @rust-lang/wg-const-eval
Configure sanitize option when compiling with a sanitizer to make
it possible to execute different code depending on whether given
sanitizer is enabled or not.
