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rust/tests/ui/rfcs/rfc-1445-restrict-constants-in-patterns/feature-gate.no_gate.stderr

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Migrate from `#[structural_match]` attribute a lang-item trait. (Or more precisely, a pair of such traits: one for `derive(PartialEq)` and one for `derive(Eq)`.) ((The addition of the second marker trait, `StructuralEq`, is largely a hack to work-around `fn (&T)` not implementing `PartialEq` and `Eq`; see also issue rust-lang/rust#46989; otherwise I would just check if `Eq` is implemented.)) Note: this does not use trait fulfillment error-reporting machinery; it just uses the trait system to determine if the ADT was tagged or not. (Nonetheless, I have kept an `on_unimplemented` message on the new trait for structural_match check, even though it is currently not used.) Note also: this does *not* resolve the ICE from rust-lang/rust#65466, as noted in a comment added in this commit. Further work is necessary to resolve that and other problems with the structural match checking, especially to do so without breaking stable code (adapted from test fn-ptr-is-structurally-matchable.rs): ```rust fn r_sm_to(_: &SM) {} fn main() { const CFN6: Wrap<fn(&SM)> = Wrap(r_sm_to); let input: Wrap<fn(&SM)> = Wrap(r_sm_to); match Wrap(input) { Wrap(CFN6) => {} Wrap(_) => {} }; } ``` where we would hit a problem with the strategy of unconditionally checking for `PartialEq` because the type `for <'a> fn(&'a SM)` does not currently even *implement* `PartialEq`. ---- added review feedback: * use an or-pattern * eschew `return` when tail position will do. * don't need fresh_expansion; just add `structural_match` to appropriate `allow_internal_unstable` attributes. also fixed example in doc comment so that it actually compiles.
2019-10-17 03:54:37 -05:00
error[E0658]: use of unstable library feature 'structural_match'
--> $DIR/feature-gate.rs:29:6
Moved compile-fail tests to ui tests.
2018-08-08 07:28:26 -05:00
|
Migrate from `#[structural_match]` attribute a lang-item trait. (Or more precisely, a pair of such traits: one for `derive(PartialEq)` and one for `derive(Eq)`.) ((The addition of the second marker trait, `StructuralEq`, is largely a hack to work-around `fn (&T)` not implementing `PartialEq` and `Eq`; see also issue rust-lang/rust#46989; otherwise I would just check if `Eq` is implemented.)) Note: this does not use trait fulfillment error-reporting machinery; it just uses the trait system to determine if the ADT was tagged or not. (Nonetheless, I have kept an `on_unimplemented` message on the new trait for structural_match check, even though it is currently not used.) Note also: this does *not* resolve the ICE from rust-lang/rust#65466, as noted in a comment added in this commit. Further work is necessary to resolve that and other problems with the structural match checking, especially to do so without breaking stable code (adapted from test fn-ptr-is-structurally-matchable.rs): ```rust fn r_sm_to(_: &SM) {} fn main() { const CFN6: Wrap<fn(&SM)> = Wrap(r_sm_to); let input: Wrap<fn(&SM)> = Wrap(r_sm_to); match Wrap(input) { Wrap(CFN6) => {} Wrap(_) => {} }; } ``` where we would hit a problem with the strategy of unconditionally checking for `PartialEq` because the type `for <'a> fn(&'a SM)` does not currently even *implement* `PartialEq`. ---- added review feedback: * use an or-pattern * eschew `return` when tail position will do. * don't need fresh_expansion; just add `structural_match` to appropriate `allow_internal_unstable` attributes. also fixed example in doc comment so that it actually compiles.
2019-10-17 03:54:37 -05:00
LL | impl std::marker::StructuralPartialEq for Foo { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Moved compile-fail tests to ui tests.
2018-08-08 07:28:26 -05:00
|
--bless --compare-mode=nll
2020-02-07 06:07:02 -06:00
= note: see issue #31434 <https://github.com/rust-lang/rust/issues/31434> for more information
normalize use of backticks in compiler messages for libsyntax/feature_gate https://github.com/rust-lang/rust/issues/60532
2019-07-09 04:32:08 -05:00
= help: add `#![feature(structural_match)]` to the crate attributes to enable
Moved compile-fail tests to ui tests.
2018-08-08 07:28:26 -05:00
Migrate from `#[structural_match]` attribute a lang-item trait. (Or more precisely, a pair of such traits: one for `derive(PartialEq)` and one for `derive(Eq)`.) ((The addition of the second marker trait, `StructuralEq`, is largely a hack to work-around `fn (&T)` not implementing `PartialEq` and `Eq`; see also issue rust-lang/rust#46989; otherwise I would just check if `Eq` is implemented.)) Note: this does not use trait fulfillment error-reporting machinery; it just uses the trait system to determine if the ADT was tagged or not. (Nonetheless, I have kept an `on_unimplemented` message on the new trait for structural_match check, even though it is currently not used.) Note also: this does *not* resolve the ICE from rust-lang/rust#65466, as noted in a comment added in this commit. Further work is necessary to resolve that and other problems with the structural match checking, especially to do so without breaking stable code (adapted from test fn-ptr-is-structurally-matchable.rs): ```rust fn r_sm_to(_: &SM) {} fn main() { const CFN6: Wrap<fn(&SM)> = Wrap(r_sm_to); let input: Wrap<fn(&SM)> = Wrap(r_sm_to); match Wrap(input) { Wrap(CFN6) => {} Wrap(_) => {} }; } ``` where we would hit a problem with the strategy of unconditionally checking for `PartialEq` because the type `for <'a> fn(&'a SM)` does not currently even *implement* `PartialEq`. ---- added review feedback: * use an or-pattern * eschew `return` when tail position will do. * don't need fresh_expansion; just add `structural_match` to appropriate `allow_internal_unstable` attributes. also fixed example in doc comment so that it actually compiles.
2019-10-17 03:54:37 -05:00
error[E0658]: use of unstable library feature 'structural_match'
--> $DIR/feature-gate.rs:31:6
|
LL | impl std::marker::StructuralEq for Foo { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^
|
--bless --compare-mode=nll
2020-02-07 06:07:02 -06:00
= note: see issue #31434 <https://github.com/rust-lang/rust/issues/31434> for more information
Migrate from `#[structural_match]` attribute a lang-item trait. (Or more precisely, a pair of such traits: one for `derive(PartialEq)` and one for `derive(Eq)`.) ((The addition of the second marker trait, `StructuralEq`, is largely a hack to work-around `fn (&T)` not implementing `PartialEq` and `Eq`; see also issue rust-lang/rust#46989; otherwise I would just check if `Eq` is implemented.)) Note: this does not use trait fulfillment error-reporting machinery; it just uses the trait system to determine if the ADT was tagged or not. (Nonetheless, I have kept an `on_unimplemented` message on the new trait for structural_match check, even though it is currently not used.) Note also: this does *not* resolve the ICE from rust-lang/rust#65466, as noted in a comment added in this commit. Further work is necessary to resolve that and other problems with the structural match checking, especially to do so without breaking stable code (adapted from test fn-ptr-is-structurally-matchable.rs): ```rust fn r_sm_to(_: &SM) {} fn main() { const CFN6: Wrap<fn(&SM)> = Wrap(r_sm_to); let input: Wrap<fn(&SM)> = Wrap(r_sm_to); match Wrap(input) { Wrap(CFN6) => {} Wrap(_) => {} }; } ``` where we would hit a problem with the strategy of unconditionally checking for `PartialEq` because the type `for <'a> fn(&'a SM)` does not currently even *implement* `PartialEq`. ---- added review feedback: * use an or-pattern * eschew `return` when tail position will do. * don't need fresh_expansion; just add `structural_match` to appropriate `allow_internal_unstable` attributes. also fixed example in doc comment so that it actually compiles.
2019-10-17 03:54:37 -05:00
= help: add `#![feature(structural_match)]` to the crate attributes to enable
error: aborting due to 2 previous errors
Moved compile-fail tests to ui tests.
2018-08-08 07:28:26 -05:00
For more information about this error, try `rustc --explain E0658`.
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