Better error message for generic_const_exprs inference failure
Fixes#90531
This code:
```rs
#![feature(generic_const_exprs)]
fn foo<const N: usize>(_arr: [u64; N + 1]) where [u64; N + 1]: {}
fn main() {
let arr = [5; 5];
foo(arr);
}
```
Will now emit the following error:
```rs
warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
--> test.rs:1:12
|
1 | #![feature(generic_const_exprs)]
| ^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
error[E0284]: type annotations needed
--> test.rs:8:7
|
8 | foo(arr);
| ^^^ cannot infer the value of the const parameter `N` declared on the function `foo`
|
note: required by a bound in `foo`
--> test.rs:3:56
|
3 | fn foo<const N: usize>(_arr: [u64; N + 1]) where [u64; N + 1]: {}
| ^^^^^ required by this bound in `foo`
help: consider specifying the generic argument
|
8 | foo::<N>(arr);
| +++++
error: aborting due to previous error; 1 warning emitted
```
cc: `@lcnr` thanks a lot again for the help on this
Move abstract const to middle
Moves AbstractConst (and all associated methods) to rustc middle for use in `rustc_infer`.
This allows for const resolution in infer to use abstract consts to walk consts and check if
they are resolvable.
This attempts to resolve the issue where `Foo<{ concrete const }, generic T>` is incorrectly marked as conflicting, and is independent from the other issue where nested abstract consts must be resolved.
r? `@lcnr`
Emit warning when named arguments are used positionally in format
Addresses Issue 98466 by emitting an error if a named argument
is used like a position argument (i.e. the name is not used in
the string to be formatted).
Fixes rust-lang#98466
remove allow(rustc::potential_query_instability) in rustc_span
Also, avoid sorting before debug output as iteration order can now be
relied upon.
Related #84447
Implement `for<>` lifetime binder for closures
This PR implements RFC 3216 ([TI](https://github.com/rust-lang/rust/issues/97362)) and allows code like the following:
```rust
let _f = for<'a, 'b> |a: &'a A, b: &'b B| -> &'b C { b.c(a) };
// ^^^^^^^^^^^--- new!
```
cc ``@Aaron1011`` ``@cjgillot``
Always create elided lifetime parameters for functions
Anonymous and elided lifetimes in functions are sometimes (async fns) --and sometimes not (regular fns)-- desugared to implicit generic parameters.
This difference of treatment makes it some downstream analyses more complicated to handle. This step is a pre-requisite to perform lifetime elision resolution on AST.
There is currently an inconsistency in the treatment of argument-position impl-trait for functions and async fns:
```rust
trait Foo<'a> {}
fn foo(t: impl Foo<'_>) {} //~ ERROR missing lifetime specifier
async fn async_foo(t: impl Foo<'_>) {} //~ OK
fn bar(t: impl Iterator<Item = &'_ u8>) {} //~ ERROR missing lifetime specifier
async fn async_bar(t: impl Iterator<Item = &'_ u8>) {} //~ OK
```
The current implementation reports "missing lifetime specifier" on `foo`, but **accepts it** in `async_foo`.
This PR **proposes to accept** the anonymous lifetime in both cases as an extra generic lifetime parameter.
This change would be insta-stable, so let's ping t-lang.
Anonymous lifetimes in GAT bindings keep being forbidden:
```rust
fn foo(t: impl Foo<Assoc<'_> = Bar<'_>>) {}
^^ ^^
forbidden ok
```
I started a discussion here: https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Anonymous.20lifetimes.20in.20universal.20impl-trait/near/284968606
r? ``@petrochenkov``
Fix drop-tracking ICE when a struct containing a field with a significant drop is used across an await
Previously, drop-tracking would incorrectly assume the struct would be dropped immediately, which was not true.
Fixes#98476. Also fixes https://github.com/rust-lang/rust/issues/98477, I think because the parent HIR node for type variables is the whole function instead of the expression where the variable is used.
r? `@eholk`
Addresses Issue 98466 by emitting a warning if a named argument
is used like a position argument (i.e. the name is not used in
the string to be formatted).
Fixes rust-lang#98466
Pull Derefer before ElaborateDrops
_Follow up work to #97025#96549#96116#95887 #95649_
This moves `Derefer` before `ElaborateDrops` and creates a new `Rvalue` called `VirtualRef` that allows us to bypass many constraints for `DerefTemp`.
r? `@oli-obk`
Refactor: remove an unnecessary `span_to_snippet`
`span_suggestion_hidden` does not show the suggested code and the suggestion is used just for rustfix, so `span_to_snippet` is unnecessary here.
Keep unstable target features for asm feature checking
Inline assembly uses the target features to determine which registers
are available on the current target. However it needs to be able to
access unstable target features for this.
Fixes#99071
diagnostics: error messages when struct literals fail to parse
If an expression is supplied where a field is expected, the parser can become convinced that it's a shorthand field syntax when it's not.
This PR addresses it by explicitly recording the permitted `:` token immediately after the identifier, and also adds a suggestion to insert the name of the field if it looks like a complex expression.
Fixes#98917
Lower let-else in MIR
This MR will switch to lower let-else statements in MIR building instead.
To lower let-else in MIR, we build a mini-switch two branches. One branch leads to the matching case, and the other leads to the `else` block. This arrangement will allow temporary lifetime analysis running as-is so that the temporaries are properly extended according to the same rule applied to regular `let` statements.
cc https://github.com/rust-lang/rust/issues/87335Fix#98672
interpret: refactor projection handling code
Moves our projection handling code into a common file, and avoids the use of a
general mplace-based fallback function by have more specialized implementations.
mplace_index (and the other slice-related functions) could be more efficient by
copy-pasting the body of operand_index. Or we could do some trait magic to share
the code between them. But for now this is probably fine.
This is the common part of https://github.com/rust-lang/rust/pull/99013 and https://github.com/rust-lang/rust/pull/99097. I am seeing some strange perf results so this probably should be its own change so we know which diff caused which perf changes...
r? `@oli-obk`
