Stabilize `-Zdwarf-version` as `-Cdwarf-version`
I propose stabilizing `-Zdwarf-version` as `-Cdwarf-version`. This PR adds a new `-Cdwarf-version` flag, leaving the unstable `-Z` flag as is to ease the transition period. The `-Z` flag will be removed in the future.
# `-Zdwarf-version` stabilization report
## What is the RFC for this feature and what changes have occurred to the user-facing design since the RFC was finalized?
No RFC/MCP, this flag was added in https://github.com/rust-lang/rust/pull/98350 and was not deemed large enough to require additional process.
The tracking issue for this feature is #103057.
## What behavior are we committing to that has been controversial? Summarize the major arguments pro/con.
None that has been extensively debated but there are a few questions that could have been chosen differently:
1. What should the flag name be?
The current flag name is very specific to DWARF. Other debuginfo formats exist (msvc's CodeView format or https://en.wikipedia.org/wiki/Stabs) so we could have chosen to generalize the flag name (`-{C,Z} debuginfo-version=dwarf-5` for example). While this would extend cleanly to support formats other than DWARF, there are some downsides to this design. Neither CodeView nor Stabs have specification or format versions so it's not clear what values would be supported beyond `dwarf-{2,3,4,5}` or `codeview`. We would also need to take care to ensure the name does not lead users to think they can pick a format other than one supported by the target. For instance, what would `--target x86_64-pc-windows-msvc -Cdebuginfo-version=dwarf-5` do?
2. What is the behavior when flag is used on targets that do not support DWARF?
Currently, passing `-{C,Z} dwarf-version` on targets like `*-windows-msvc` does not do anything. It may be preferable to emit a warning alerting the user that the flag has no effect on the target platform. Alternatively, we could emit an error but this could be annoying since it would require the use of target specific RUSTFLAGS to use the flag correctly (and there isn't a way to target "any platform that uses DWARF" using cfgs).
3. Does the precompiled standard library potentially using a different version of DWARF a problem?
I don't believe this is an issue as debuggers (and other such tools) already must deal with the possibility that an application uses different DWARF versions across its statically or dynamically linked libraries.
## Are there extensions to this feature that remain unstable? How do we know that we are not accidentally committing to those.
No extensions per se, although future DWARF versions could be considered as such. At present, we validate the requested DWARF version is between 2 and 5 (inclusive) so new DWARF versions will not automatically be supported until the validation logic is adjusted.
## Summarize the major parts of the implementation and provide links into the code (or to PRs)
- Targets define their preferred or default DWARF version: 34a5ea911c/compiler/rustc_target/src/spec/mod.rs (L2369)
- We use the target default but this can be overriden by `-{C,Z} dwarf-version` 34a5ea911c/compiler/rustc_session/src/session.rs (L738)
- The flag is validated 34a5ea911c/compiler/rustc_session/src/session.rs (L1253-L1258)
- When debuginfo is generated, we tell LLVM to use the requested value or the target default 34a5ea911c/compiler/rustc_codegen_llvm/src/debuginfo/mod.rs (L106)
## Summarize existing test coverage of this feature
- Test that we actually generate the appropriate DWARF version
- https://github.com/rust-lang/rust/blob/master/tests/assembly/dwarf5.rs
- https://github.com/rust-lang/rust/blob/master/tests/assembly/dwarf4.rs
- Test that LTO with different DWARF versions picks the highest version
- https://github.com/rust-lang/rust/blob/master/tests/assembly/dwarf-mixed-versions-lto.rs
- Test DWARF versions 2-5 are valid while 0, 1 and 6 report an error
- https://github.com/rust-lang/rust/blob/master/tests/ui/debuginfo/dwarf-versions.rs
- Ensure LLVM does not report a warning when LTO'ing different DWARF versions together
- https://github.com/rust-lang/rust/blob/master/tests/ui/lto/dwarf-mixed-versions-lto.rs
## Has a call-for-testing period been conducted? If so, what feedback was received?
No call-for-testing has been conducted but Rust for Linux has been using this flag without issue.
## What outstanding bugs in the issue tracker involve this feature? Are they stabilization-blocking?
All reported bugs have been resolved.
## Summarize contributors to the feature by name for recognition and assuredness that people involved in the feature agree with stabilization
- Initial implementation in https://github.com/rust-lang/rust/pull/98350 by `@pcwalton`
- Stop emitting `.debug_pubnames` and `.debug_pubtypes` when using DWARF 5 in https://github.com/rust-lang/rust/pull/117962 by `@weihanglo.`
- Refactoring & cleanups (#135739), fix LLVM warning on LTO with different DWARF versions (#136659) and argument validation (#136746) by `@wesleywiser`
## What FIXMEs are still in the code for that feature and why is it ok to leave them there?
No FIXMEs related to this feature.
## What static checks are done that are needed to prevent undefined behavior?
This feature cannot cause undefined behavior.
We ensure the DWARF version is one of the supported values [here](34a5ea911c/compiler/rustc_session/src/session.rs (L1255-L1257)).
## In what way does this feature interact with the reference/specification, and are those edits prepared?
No changes to reference/spec, unstable rustc docs are moved to the stable book as part of the stabilization PR.
## Does this feature introduce new expressions and can they produce temporaries? What are the lifetimes of those temporaries?
No.
## What other unstable features may be exposed by this feature?
`-Zembed-source` requires use of DWARF 5 extensions but has its own feature gate.
## What is tooling support like for this feature, w.r.t rustdoc, clippy, rust-analzyer, rustfmt, etc.?
No support needed for rustdoc, clippy, rust-analyzer, rustfmt or rustup.
Cargo could expose this as an option in build profiles but I would expect the decision as to what version should be used would be made for the entire crate graph at build time rather than by individual package authors.
cc-rs has support for detecting the presence of `-{C,Z} dwarf-version` in `RUSTFLAGS` and providing the corresponding flag to Clang/gcc (https://github.com/rust-lang/cc-rs/pull/1395).
---
Closes#103057
Split `TypeFolder` and `FallibleTypeFolder` atwain
Right now there is a coherence problem with `TypeFolder` and `FallibleTypeFolder`. Namely, it's impossible to implement a `FallibleTypeFolder` that is generic over interner, b/c it has a *downstream* conflict with the blanket impl:
```
impl<I, F> FallibleTypeFolder<I> for F where F: TypeFolder<I> {}
```
Because downstream crates may implement `TypeFolder<SomeLocalInterner>` for the fallible type folder.
This PR removes the relationship between `FallibleTypeFolder` and `TypeFolder`; it leads to *modest* code duplication, but otherwise does not affect perf and really doesn't matter in general.
Reject test executables when not supported by target
Currently, compiling tests for SOLID produces an ICE, because SOLID does not support executables.
See https://github.com/rust-lang/rust/issues/138047
Fix: Map EOPNOTSUPP to ErrorKind::Unsupported on Unix
This change maps the EOPNOTSUPP errno value (95) to std::io::ErrorKind::Unsupported in the decode_error_kind function for Unix platforms. Previously, it was incorrectly mapped to ErrorKind::Uncategorized.
Fixes#139803
Let CStrings be either 1 or 2 byte aligned.
We see a regression on the `tests/assembly/cstring-merging.rs` test on s390x.
Some architectures (like s390x) require strings to be 2 byte aligned. Therefor the section name will be marked with a .2 postfix on this architectures.
Allowing a section name with a .1 or .2 postfix will make the test pass on either platform.
std/thread: Use default stack size from menuconfig for NuttX
* Update comments to clarify the usage of zero as an indication for default stack size configuration
* Adjust conditional compilation to reflect the changes in stack size handling for the NuttX platform
This change improves clarity and consistency in stack size configuration across platforms.
std: sys: process: uefi: Use NULL stdin by default
According to the docs in `Command::output`:
> By default, stdout and stderr are captured (and used to provide the
resulting output). Stdin is not inherited from the parent and any attempt by the child process to read from the stdin stream will result in the stream immediately closing.
This was being violated by UEFI which was inheriting stdin by default.
While the docs don't explicitly state that the default should be NULL, the behaviour seems like reading from NULL.
UEFI however, has a bit of a problem. The `EFI_SIMPLE_TEXT_INPUT_PROTOCOL` only provides support for reading 1 key press. This means that you either get an error, or it is assumed that the keypress was read successfully. So there is no way to have a successful read of length 0. Currently, I am returning UNSUPPORTED error when trying to read from NULL stdin. On linux however, you will get a read of length 0 for Null stdin.
One possible way to get around this is to translate one of the UEFI errors to a read 0 (Maybe unsupported?). It is also possible to have a non-standard error code, but well, not sure if we go that route.
Alternatively, if meaning of Stdio::Null is platform dependent, it should be fine to keep the current behaviour of returning an error.
cc ```@nicholasbishop``` ```@dvdhrm```
Allow const patterns of matches to contain pattern types
Trying to pattern match on a type containing a pattern type will currently fail with an ICE
```rust
error: internal compiler error: compiler/rustc_mir_build/src/builder/matches/test.rs:459:18: invalid type for non-scalar compare: (u32) is 1..
--> src/main.rs:22:5
|
22 | TWO => {}
| ^^^
```
because the compiler tries to generate a MIR `BinOp(Eq)` operation on a pattern type, which is not supported. While we could support that, there are side effects of allowing this (none that would compile, but the compiler would simultaneously think it could `==` pattern types and that it could not because `PartialEq` is not implemented. So instead I change the logic for pattern matching to transmute pattern types to their base type before comparing.
r? ```@BoxyUwU```
cc #123646 ```@scottmcm``` ```@joshtriplett```
Enable contracts for const functions
Use `const_eval_select!()` macro to enable contract checking only at runtime. The existing contract logic relies on closures, which are not supported in constant functions.
This commit also removes one level of indirection for ensures clauses since we no longer build a closure around the ensures predicate.
Resolves#136925
**Call-out:** This is still a draft PR since CI is broken due to a new warning message for unreachable code when the bottom of the function is indeed unreachable. It's not clear to me why the warning wasn't triggered before.
r? ```@compiler-errors```
