diff options
| -rw-r--r-- | src/doc/unstable-book/src/SUMMARY.md | 1 | ||||
| -rw-r--r-- | src/doc/unstable-book/src/rvalue-static-promotion.md | 5 | ||||
| -rw-r--r-- | src/librustc/middle/mem_categorization.rs | 5 | ||||
| -rw-r--r-- | src/libsyntax/feature_gate.rs | 3 | ||||
| -rw-r--r-- | src/test/compile-fail/feature-gate-rvalue_static_promotion.rs | 15 | ||||
| -rw-r--r-- | src/test/run-pass/rvalue-static-promotion.rs | 17 |
6 files changed, 43 insertions, 3 deletions
diff --git a/src/doc/unstable-book/src/SUMMARY.md b/src/doc/unstable-book/src/SUMMARY.md index 5fb323d6ce9..034f9f4eb25 100644 --- a/src/doc/unstable-book/src/SUMMARY.md +++ b/src/doc/unstable-book/src/SUMMARY.md @@ -71,6 +71,7 @@ - [repr_simd](repr-simd.md) - [rustc_attrs](rustc-attrs.md) - [rustc_diagnostic_macros](rustc-diagnostic-macros.md) +- [rvalue_static_promotion](rvalue-static-promotion.md) - [sanitizer_runtime](sanitizer-runtime.md) - [simd](simd.md) - [simd_ffi](simd-ffi.md) diff --git a/src/doc/unstable-book/src/rvalue-static-promotion.md b/src/doc/unstable-book/src/rvalue-static-promotion.md new file mode 100644 index 00000000000..3b654960c8e --- /dev/null +++ b/src/doc/unstable-book/src/rvalue-static-promotion.md @@ -0,0 +1,5 @@ +# `rvalue_static_promotion` + +The tracking issue for this feature is: [#38865] + +------------------------ diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs index b0c85e2ef4c..a669ac3a69b 100644 --- a/src/librustc/middle/mem_categorization.rs +++ b/src/librustc/middle/mem_categorization.rs @@ -843,11 +843,10 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> { let promotable = self.tcx().rvalue_promotable_to_static.borrow().get(&id).cloned() .unwrap_or(false); - // Only promote `[T; 0]` before an RFC for rvalue promotions - // is accepted. + // When the corresponding feature isn't toggled, only promote `[T; 0]`. let promotable = match expr_ty.sty { ty::TyArray(_, 0) => true, - _ => promotable & false + _ => promotable & self.tcx().sess.features.borrow().rvalue_static_promotion, }; // Compute maximum lifetime of this rvalue. This is 'static if diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs index 15913d56d16..59e9ab30e0e 100644 --- a/src/libsyntax/feature_gate.rs +++ b/src/libsyntax/feature_gate.rs @@ -342,6 +342,9 @@ declare_features! ( // Allows the `catch {...}` expression (active, catch_expr, "1.17.0", Some(31436)), + + // See rust-lang/rfcs#1414. Allows code like `let x: &'static u32 = &42` to work. + (active, rvalue_static_promotion, "1.15.1", Some(38865)), ); declare_features! ( diff --git a/src/test/compile-fail/feature-gate-rvalue_static_promotion.rs b/src/test/compile-fail/feature-gate-rvalue_static_promotion.rs new file mode 100644 index 00000000000..41dc282be41 --- /dev/null +++ b/src/test/compile-fail/feature-gate-rvalue_static_promotion.rs @@ -0,0 +1,15 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#[allow(unused_variables)] +fn main() { + let x: &'static u32 = &42; //~ error: does not live long enough + let y: &'static Option<u32> = &None; //~ error: does not live long enough +} \ No newline at end of file diff --git a/src/test/run-pass/rvalue-static-promotion.rs b/src/test/run-pass/rvalue-static-promotion.rs new file mode 100644 index 00000000000..f8d93783877 --- /dev/null +++ b/src/test/run-pass/rvalue-static-promotion.rs @@ -0,0 +1,17 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(rvalue_static_promotion)] + +#[allow(unused_variables)] +fn main() { + let x: &'static u32 = &42; + let y: &'static Option<u32> = &None; +} \ No newline at end of file |