rust/compiler/rustc_ast_lowering/messages.ftl
bors 4a2fe4491e Auto merge of #120361 - compiler-errors:async-closures, r=oli-obk
Rework support for async closures; allow them to return futures that borrow from the closure's captures

This PR implements a new lowering for async closures via `TyKind::CoroutineClosure` which handles the curious relationship between the closure and the coroutine that it returns.

I wrote up a bunch in [this hackmd](https://hackmd.io/`@compiler-errors/S1HvqQxca)` which will be copied to the dev guide after this PR lands, and hopefully left sufficient comments in the source code explaining why this change is as large as it is.

This also necessitates that they begin implementing the `AsyncFn`-family of traits, rather than the `Fn`-family of traits -- if you need `Fn` implementations, you should probably use the non-sugar `|| async {}` syntax instead.

Notably this PR does not yet implement `async Fn()` syntax sugar for bounds, but I expect to add those soon (**edit:** #120392). For now, users must use `AsyncFn()` traits directly, which necessitates adding the `async_fn_traits` feature gate as well. I will add this as a follow-up very soon.

r? oli-obk

This is based on top of #120322, but that PR is minimal.
2024-02-06 15:04:01 +00:00

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ast_lowering_abi_specified_multiple_times =
`{$prev_name}` ABI specified multiple times
.label = previously specified here
.note = these ABIs are equivalent on the current target
ast_lowering_arbitrary_expression_in_pattern =
arbitrary expressions aren't allowed in patterns
ast_lowering_argument = argument
ast_lowering_assoc_ty_parentheses =
parenthesized generic arguments cannot be used in associated type constraints
ast_lowering_async_bound_not_on_trait =
`async` bound modifier only allowed on trait, not `{$descr}`
ast_lowering_async_bound_only_for_fn_traits =
`async` bound modifier only allowed on `Fn`/`FnMut`/`FnOnce` traits
ast_lowering_async_coroutines_not_supported =
`async` coroutines are not yet supported
ast_lowering_att_syntax_only_x86 =
the `att_syntax` option is only supported on x86
ast_lowering_await_only_in_async_fn_and_blocks =
`await` is only allowed inside `async` functions and blocks
.label = only allowed inside `async` functions and blocks
ast_lowering_bad_return_type_notation_inputs =
argument types not allowed with return type notation
.suggestion = remove the input types
ast_lowering_bad_return_type_notation_output =
return type not allowed with return type notation
.suggestion = remove the return type
ast_lowering_base_expression_double_dot =
base expression required after `..`
.suggestion = add a base expression here
ast_lowering_clobber_abi_not_supported =
`clobber_abi` is not supported on this target
ast_lowering_closure_cannot_be_static = closures cannot be static
ast_lowering_coroutine_too_many_parameters =
too many parameters for a coroutine (expected 0 or 1 parameters)
ast_lowering_does_not_support_modifiers =
the `{$class_name}` register class does not support template modifiers
ast_lowering_extra_double_dot =
`..` can only be used once per {$ctx} pattern
.label = can only be used once per {$ctx} pattern
ast_lowering_functional_record_update_destructuring_assignment =
functional record updates are not allowed in destructuring assignments
.suggestion = consider removing the trailing pattern
ast_lowering_generic_param_default_in_binder =
defaults for generic parameters are not allowed in `for<...>` binders
ast_lowering_generic_type_with_parentheses =
parenthesized type parameters may only be used with a `Fn` trait
.label = only `Fn` traits may use parentheses
ast_lowering_inclusive_range_with_no_end = inclusive range with no end
ast_lowering_inline_asm_unsupported_target =
inline assembly is unsupported on this target
ast_lowering_invalid_abi =
invalid ABI: found `{$abi}`
.label = invalid ABI
.note = invoke `{$command}` for a full list of supported calling conventions.
ast_lowering_invalid_abi_clobber_abi =
invalid ABI for `clobber_abi`
.note = the following ABIs are supported on this target: {$supported_abis}
ast_lowering_invalid_abi_suggestion = did you mean
ast_lowering_invalid_asm_template_modifier_const =
asm template modifiers are not allowed for `const` arguments
ast_lowering_invalid_asm_template_modifier_reg_class =
invalid asm template modifier for this register class
ast_lowering_invalid_asm_template_modifier_sym =
asm template modifiers are not allowed for `sym` arguments
ast_lowering_invalid_register =
invalid register `{$reg}`: {$error}
ast_lowering_invalid_register_class =
invalid register class `{$reg_class}`: {$error}
ast_lowering_match_arm_with_no_body =
`match` arm with no body
.suggestion = add a body after the pattern
ast_lowering_misplaced_assoc_ty_binding =
associated type bounds are only allowed in where clauses and function signatures, not in {$position}
ast_lowering_misplaced_double_dot =
`..` patterns are not allowed here
.note = only allowed in tuple, tuple struct, and slice patterns
ast_lowering_misplaced_impl_trait =
`impl Trait` is not allowed in {$position}
.note = `impl Trait` is only allowed in arguments and return types of functions and methods
ast_lowering_misplaced_relax_trait_bound =
`?Trait` bounds are only permitted at the point where a type parameter is declared
ast_lowering_never_pattern_with_body =
a never pattern is always unreachable
.label = this will never be executed
.suggestion = remove this expression
ast_lowering_never_pattern_with_guard =
a guard on a never pattern will never be run
.suggestion = remove this guard
ast_lowering_previously_used_here = previously used here
ast_lowering_register1 = register `{$reg1_name}`
ast_lowering_register2 = register `{$reg2_name}`
ast_lowering_register_class_only_clobber =
register class `{$reg_class_name}` can only be used as a clobber, not as an input or output
ast_lowering_register_conflict =
register `{$reg1_name}` conflicts with register `{$reg2_name}`
.help = use `lateout` instead of `out` to avoid conflict
ast_lowering_remove_parentheses = remove these parentheses
ast_lowering_sub_tuple_binding =
`{$ident_name} @` is not allowed in a {$ctx}
.label = this is only allowed in slice patterns
.help = remove this and bind each tuple field independently
ast_lowering_sub_tuple_binding_suggestion = if you don't need to use the contents of {$ident}, discard the tuple's remaining fields
ast_lowering_support_modifiers =
the `{$class_name}` register class supports the following template modifiers: {$modifiers}
ast_lowering_template_modifier = template modifier
ast_lowering_this_not_async = this is not `async`
ast_lowering_underscore_expr_lhs_assign =
in expressions, `_` can only be used on the left-hand side of an assignment
.label = `_` not allowed here
ast_lowering_use_angle_brackets = use angle brackets instead