proc_macro::is_available()
This PR adds `proc_macro::is_available() -> bool` to determine whether proc_macro has been made accessible to the currently running program.
The proc_macro crate is only intended for use inside the implementation of procedural macros. All the functions in the crate panic if invoked from outside of a procedural macro, such as from a build script or unit test or ordinary Rust binary.
Unfortunately those panics made it impossible for libraries that are designed to support both macro and non-macro use cases (e.g. Syn) to be used from binaries that are compiled with panic=abort. In panic=unwind mode we're able to attempt a proc macro call inside catch_unwind and use libproc_macro's result if it succeeds, otherwise fall back to a non-macro alternative implementation. But in panic=abort there was no way to determine which implementation needs to be used.
r? @eddyb
attn: @petrochenkov @adetaylor
ref: https://github.com/dtolnay/cxx/issues/130
Lint must_use on mem::replace
This adds a hint on `mem::replace`, "if you don't need the old value,
you can just assign the new value directly". This is in similar spirit
to the `must_use` on `ManuallyDrop::take`.
Added detailed error code explanation for issue E0696 in Rust compiler.
Added proper error explanation for issue E0696 in the Rust compiler.
Error Code E0696
Sub Part of Issue #61137
r? @GuillaumeGomez
Exhaustively match on `{Statement,Terminator}Kind` during const checking
This adds a pre-monomorphization error for inline assembly in a const context as well.
r? @oli-obk
Clarify unused_doc_comments note on macro invocations
The previous error message used to say:
<pre>
/// doc
^^^^^^^ rustdoc does not generate documentation for <b>macros</b>
</pre>
Obviously we do generate documentation for macros, such as https://docs.rs/bitflags/1.2.1/bitflags/macro.bitflags.html. It's only macro invocations that don't get their own docs. This PR updates the message to say "rustdoc does not generate documentation for <b>macro invocations</b>".
I observe that prior to #69084 this used to say "rustdoc does not generate documentation for **macro expansions**", as implemented originally in #57882. I don't have a preference between those but I made the commit before looking up the history.
r? @Manishearth
attn: @yaahc @euclio
Detect mistyped associated consts in `Instance::resolve`.
*Based on #71049 to prevent redundant/misleading downstream errors.*
Fixes#70942 by refusing to resolve an associated `const` if it doesn't have the same type in the `impl` that it does in the `trait` (which we assume had errored, and `delay_span_bug` guards against bugs).
Suggest `-> impl Trait` and `-> Box<dyn Trait>` on fn that doesn't return
During development, a function could have a return type set that is a
bare trait object by accident. We already suggest using either a boxed
trait object or `impl Trait` if the return paths will allow it. We now
do so too when there are *no* return paths or they all resolve to `!`.
We still don't handle cases where the trait object is *not* the entirety
of the return type gracefully.
Closes#38376.
Check that main/start is not async
* Add new error code E0752
* Add span to hir::IsAsync::Yes
* Emit an error if main or the start function is marked as async
* Add two regression tests
This PR fixes#68523.
When the return type is `!Sized` we look for all the returned
expressions in the body to fetch their types and provide a reasonable
suggestion. The tail expression of the body is normally evaluated after
checking whether the return type is `Sized`. Changing the order of the
evaluation produces undesirable knock down effects, so we detect the
specific case that newcomers are likely to encounter ,returning a single
bare trait object, and only in that case we evaluate the tail
expression's type so that the suggestion will be accurate.
During development, a function could have a return type set that is a
bare trait object by accident. We already suggest using either a boxed
trait object or `impl Trait` if the return paths will allow it. We now
do so too when there are *no* return paths or they all resolve to `!`.
We still don't handle cases where the trait object is *not* the entirety
of the return type gracefully.
* Add new error code E0752
* Add span to hir::IsAsync::Yes
* Emit an error if main or the start function is marked as async
* Add two regression tests
Fix formatting errors and bless test outputs
* move tests to ui/async-await
fix test error text
remove span from IsAsync
Deprecate the asm! macro in favor of llvm_asm!
Since we will be changing the syntax of `asm!` soon, deprecate it and encourage people to use `llvm_asm!` instead (which preserves the old syntax). This will avoid breakage when `asm!` is changed.
RFC: https://github.com/rust-lang/rfcs/pull/2843
Make `needs_drop` less pessimistic on generators
Generators only have non-trivial drop logic when they may store (in upvars or across yields) a type that does.
This prevents generation of some unnecessary MIR in simple generators. There might be some impact on compile times, but this is probably limited in real-world applications.
~~This builds off of https://github.com/rust-lang/rust/pull/69814 since that contains some fixes that are made relevant by *this* PR (see https://github.com/rust-lang/rust/pull/69814#issuecomment-599147269).~~ (this has been merged)
Maintain chain of derived obligations
When evaluating the derived obligations from super traits, maintain a
reference to the original obligation in order to give more actionable
context in the output.
Continuation (and built on) #69745, subset of #69709.
r? @eddyb
When evaluating the derived obligations from super traits, maintain a
reference to the original obligation in order to give more actionable
context in the output.
miri-unleashed: test that we detect heap allocations
This removes the second-to-last use of `IS_SUPPORTED_IN_MIRI = false`.
r? @ecstatic-morse @oli-obk
