bors fc6b5d6efe Auto merge of #67216 - ecstatic-morse:const-loop, r=oli-obk ... Enable `loop` and `while` in constants behind a feature flag This PR is an initial implementation of #52000. It adds a `const_loop` feature gate, which allows `while` and `loop` expressions through both HIR and MIR const-checkers if enabled. `for` expressions remain forbidden by the HIR const-checker, since they desugar to a call to `IntoIterator::into_iter`, which will be rejected anyways. `while` loops also require [`#![feature(const_if_match)]`](https://github.com/rust-lang/rust/pull/66507), since they have a conditional built into them. The diagnostics from the HIR const checker will suggest this to the user. r? @oli-obk cc @rust-lang/wg-const-eval		2019-12-15 01:28:28 +00:00
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accepted.rs	Revert "Stabilize the never_type, written !."	2019-12-14 09:01:09 -05:00
active.rs	Auto merge of #67216 - ecstatic-morse:const-loop, r=oli-obk	2019-12-15 01:28:28 +00:00
builtin_attrs.rs	Require stable/unstable annotations for the constness of all stable functions with a const modifier	2019-12-13 11:27:02 +01:00
Cargo.toml	builtin_attrs.rs -> rustc_feature	2019-11-30 02:34:18 +01:00
lib.rs	move GateIssue to rustc_feature & simplify emit_feature_err	2019-11-30 07:40:28 +01:00
removed.rs	introduce crate rustc_feature and move active, accepted, and removed to it	2019-11-30 00:25:40 +01:00