- fix for divergence
- fix error message
- fix another cranelift test
- fix some cranelift things
- don't set the NORETURN option for naked asm
- fix use of naked_asm! in doc comment
- fix use of naked_asm! in run-make test
- use `span_bug` in unreachable branch
make type-check-4 asm tests about non-const expressions
These tests recently got changed in https://github.com/rust-lang/rust/pull/129759. I asked the PR author to make the tests read from a `static mut` (rather than just making them "pass"), but I now think that was a mistake: previously the tests failed because the const was not a valid const expression, after the PR they failed because the const failed to evaluate.
So this PR restores the tests to "fail because the const is not a valid const expression". That can be done in a target-independent way so I unified the x86 and aarch64 tests into one.
Cc `@oli-obk` as the original [author](https://github.com/rust-lang/rust/commit/0d88631059742db30c44edadd1c8a2f51c8eb971) of these tests -- not sure if you still remember what they were intended to test.
Fix error span if arg to `asm!()` is a macro call
Fixes#129503
When the argument to `asm!()` is a macro call, e.g. `asm!(concat!("abc", "{} pqr"))`, and there's an error in the resulting template string, we do not take into account the presence of this macro call while computing the error span. This PR fixes that. Now we will use the entire thing between the parenthesis of `asm!()` as the error span in this situation e.g. for `asm!(concat!("abc", "{} pqr"))` the error span will be `concat!("abc", "{} pqr")`.
When the template string passed to asm!() is produced by
a macro call like concat!() we were producing wrong error
spans. Now in the case of a macro call we just use the entire
arg to asm!(), macro call and all, as the error span.
in this commit, `naked_asm!` is an alias for `asm!` with one difference: `options(noreturn)` is always enabled by `naked_asm!`. That makes it future-compatible for when `naked_asm!` starts disallowing `options(noreturn)` later.
add repr to the allowlist for naked functions
Fixes#129412 (combining unstable features #90957 (`#![feature(naked_functions)]`) and #82232 (`#![feature(fn_align)]`)
Tweak type inference for `const` operands in inline asm
Previously these would be treated like integer literals and default to `i32` if a type could not be determined. To allow for forward-compatibility with `str` constants in the future, this PR changes type inference to use an unbound type variable instead.
The actual type checking is deferred until after typeck where we still ensure that the final type for the `const` operand is an integer type.
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improve error message when `global_asm!` uses `asm!` operands
follow-up to https://github.com/rust-lang/rust/pull/128207
what was
```
error: expected expression, found keyword `in`
--> src/lib.rs:1:31
|
1 | core::arch::global_asm!("{}", in(reg));
| ^^ expected expression
```
becomes
```
error: the `in` operand cannot be used with `global_asm!`
--> $DIR/parse-error.rs:150:19
|
LL | global_asm!("{}", in(reg));
| ^^ the `in` operand is not meaningful for global-scoped inline assembly, remove it
```
the span of the error is just the keyword, which means that we can't create a machine-applicable suggestion here. The alternative would be to attempt to parse the full operand, but then if there are syntax errors in the operand those would be presented to the user, even though the parser already knows that the output won't be valid. Also that would require more complexity in the parser.
So I think this is a nice improvement at very low cost.
`#[naked]`: report incompatible attributes
tracking issue: https://github.com/rust-lang/rust/issues/90957
this is a re-implementation of https://github.com/rust-lang/rust/pull/93809 by ``@bstrie`` which was closed 2 years ago due to inactivity.
This PR takes some of the final comments into account, specifically providing a little more context in error messages, and using an allow list to determine which attributes are compatible with `#[naked]`.
Notable attributes that are incompatible with `#[naked]` are:
* `#[inline]`
* `#[track_caller]`
* ~~`#[target_feature]`~~ (this is now allowed, see PR discussion)
* `#[test]`, `#[ignore]`, `#[should_panic]`
These attributes just directly conflict with what `#[naked]` should do.
Naked functions are still important for systems programming, embedded, and operating systems, so I'd like to move them forward.
- merge error codes
- use attribute name that is incompatible in error message
- add test for conditional incompatible attribute
- add `linkage` to the allowlist
`#[naked]`: use an allowlist for allowed options on `asm!` in naked functions
tracking issue: https://github.com/rust-lang/rust/issues/90957
this is mostly just a refactor, but using an allowlist (rather than a denylist) for which asm options are allowed in naked functions is a little safer.
These options are disallowed because naked functions are effectively global asm, but defined using inline asm.
The link pointed to a closed issue. Create a new one and point the link
to it.
Also add a help message to hint what change the user could make.
Fixes: https://github.com/rust-lang/rust/issues/127821
In <https://github.com/rust-lang/rust/pull/126922>, the
`binary_asm_labels` lint was added which flags labels such as `0:` and
`1:`. Before that change, LLVM was giving a confusing error on
x86/x86_64 because of an incorrect interpretation.
However, targets other than x86 and x86_64 never had the error message
and have not been a problem. This means that the lint was causing code
that previously worked to start failing (e.g. `compiler_builtins`),
rather than only providing a more clear messages where there has always
been an error.
Adjust the lint to only fire on x86 and x86_64 assembly to avoid this
regression.
add lint for inline asm labels that look like binary
fixes#94426
Due to a bug/feature in LLVM, labels composed of only the digits `0` and `1` can sometimes be confused with binary literals, even if a binary literal would not be valid in that position.
This PR adds detection for such labels and also as a drive-by change, adds a note to cases such as `asm!(include_str!("file"))` that the label that it found came from an expansion of a macro, it wasn't found in the source code.
I expect this PR to upset some people that were using labels `0:` or `1:` without issue because they never hit the case where LLVM got it wrong, but adding a heuristic to the lint to prevent this is not feasible - it would involve writing a whole assembly parser for every target that we have assembly support for.
[zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202024-06-20/near/445870628)
r? ``@estebank``
Folkert de Vries