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Rollup merge of #68114 - ecstatic-morse:fix-feature-gating, r=Centril

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Don't require `allow_internal_unstable` unless `staged_api` is enabled.

#63770 changed `qualify_min_const_fn` to require `allow_internal_unstable` for *all* crates that used an unstable feature, regardless of whether `staged_api` was enabled or the `fn` that used that feature was stably const. In practice, this meant that every crate in the ecosystem that wanted to use nightly features added `#![feature(const_fn)]`, which skips `qualify_min_const_fn` entirely.

After this PR, crates that do not have `#![feature(staged_api)]` will only need to enable the feature they are interested in. For example, `#![feature(const_if_match)]` will be enough to enable `if` and `match` in constants. Crates with `staged_api` (e.g., `libstd`) require `#[allow_internal_unstable]` to be added to a function if it uses nightly features unless that function is also marked `#[rustc_const_unstable]`. This prevents proliferation of `#[allow_internal_unstable]` into functions that are not callable in a `const` context on stable.

r? @oli-obk (author of #63770)
cc @Centril
This commit is contained in:
Mazdak Farrokhzad 2020-01-11 12:36:14 +01:00 • committed by GitHub
commit 50d76d6471
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19 changed files with 66 additions and 41 deletions
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1
src/test/ui/consts/const-mut-refs/const_mut_refs.rs
View file

@ -1,7 +1,6 @@
// run-pass
#![feature(const_mut_refs)]
#![feature(const_fn)]
struct Foo {
x: usize

1
src/test/ui/consts/control-flow/exhaustive-c-like-enum-match.rs
View file

@ -3,7 +3,6 @@
// check-pass
#![feature(const_if_match)]
#![feature(const_fn)]
enum E {
A,

2
src/test/ui/consts/control-flow/feature-gate-const-if-match.if_match.stderr
View file

@ -1,5 +1,5 @@
error: fatal error triggered by #[rustc_error]
--> $DIR/feature-gate-const-if-match.rs:109:1
--> $DIR/feature-gate-const-if-match.rs:108:1
|
LL | / fn main() {
LL | | let _ = [0; {

1
src/test/ui/consts/control-flow/feature-gate-const-if-match.rs
View file

@ -6,7 +6,6 @@
#![feature(rustc_attrs)]
#![cfg_attr(if_match, feature(const_if_match))]
#![feature(const_fn)]
const _: i32 = if true { //[stock]~ ERROR `if` is not allowed in a `const`
5

50
src/test/ui/consts/control-flow/feature-gate-const-if-match.stock.stderr
View file

@ -1,5 +1,5 @@
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:11:16
--> $DIR/feature-gate-const-if-match.rs:10:16
|
LL | const _: i32 = if true {
| ________________^
@ -13,7 +13,7 @@ LL | | };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:17:16
--> $DIR/feature-gate-const-if-match.rs:16:16
|
LL | const _: i32 = if let Some(true) = Some(false) {
| ________________^
@ -27,7 +27,7 @@ LL | | };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:23:16
--> $DIR/feature-gate-const-if-match.rs:22:16
|
LL | const _: i32 = match 1 {
| ________________^
@ -41,7 +41,7 @@ LL | | };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `static`
--> $DIR/feature-gate-const-if-match.rs:30:13
--> $DIR/feature-gate-const-if-match.rs:29:13
|
LL | let x = if true { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^
@ -50,7 +50,7 @@ LL | let x = if true { 0 } else { 1 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `static`
--> $DIR/feature-gate-const-if-match.rs:32:13
--> $DIR/feature-gate-const-if-match.rs:31:13
|
LL | let x = match x { 0 => 1, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -59,7 +59,7 @@ LL | let x = match x { 0 => 1, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `static`
--> $DIR/feature-gate-const-if-match.rs:34:5
--> $DIR/feature-gate-const-if-match.rs:33:5
|
LL | if let Some(x) = Some(x) { x } else { 1 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -68,7 +68,7 @@ LL | if let Some(x) = Some(x) { x } else { 1 }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `static mut`
--> $DIR/feature-gate-const-if-match.rs:39:13
--> $DIR/feature-gate-const-if-match.rs:38:13
|
LL | let x = if true { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^
@ -77,7 +77,7 @@ LL | let x = if true { 0 } else { 1 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `static mut`
--> $DIR/feature-gate-const-if-match.rs:41:13
--> $DIR/feature-gate-const-if-match.rs:40:13
|
LL | let x = match x { 0 => 1, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -86,7 +86,7 @@ LL | let x = match x { 0 => 1, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `static mut`
--> $DIR/feature-gate-const-if-match.rs:43:5
--> $DIR/feature-gate-const-if-match.rs:42:5
|
LL | if let Some(x) = Some(x) { x } else { 1 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -95,7 +95,7 @@ LL | if let Some(x) = Some(x) { x } else { 1 }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:48:5
--> $DIR/feature-gate-const-if-match.rs:47:5
|
LL | if true { 5 } else { 6 }
| ^^^^^^^^^^^^^^^^^^^^^^^^
@ -104,7 +104,7 @@ LL | if true { 5 } else { 6 }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:52:5
--> $DIR/feature-gate-const-if-match.rs:51:5
|
LL | / if let Some(true) = a {
LL | | 0
@ -117,7 +117,7 @@ LL | | }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:60:5
--> $DIR/feature-gate-const-if-match.rs:59:5
|
LL | / match i {
LL | | i if i > 10 => i,
@ -130,7 +130,7 @@ LL | | }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:91:17
--> $DIR/feature-gate-const-if-match.rs:90:17
|
LL | let x = if y { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^
@ -139,7 +139,7 @@ LL | let x = if y { 0 } else { 1 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:93:17
--> $DIR/feature-gate-const-if-match.rs:92:17
|
LL | let x = match x { 0 => 1, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -148,7 +148,7 @@ LL | let x = match x { 0 => 1, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const fn`
--> $DIR/feature-gate-const-if-match.rs:95:9
--> $DIR/feature-gate-const-if-match.rs:94:9
|
LL | if let Some(x) = Some(x) { x } else { 1 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -157,7 +157,7 @@ LL | if let Some(x) = Some(x) { x } else { 1 }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:111:17
--> $DIR/feature-gate-const-if-match.rs:110:17
|
LL | let x = if false { 0 } else { 1 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^
@ -166,7 +166,7 @@ LL | let x = if false { 0 } else { 1 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:113:17
--> $DIR/feature-gate-const-if-match.rs:112:17
|
LL | let x = match x { 0 => 1, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -175,7 +175,7 @@ LL | let x = match x { 0 => 1, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:115:9
--> $DIR/feature-gate-const-if-match.rs:114:9
|
LL | if let Some(x) = Some(x) { x } else { 1 }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -184,7 +184,7 @@ LL | if let Some(x) = Some(x) { x } else { 1 }
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:68:21
--> $DIR/feature-gate-const-if-match.rs:67:21
|
LL | const IF: i32 = if true { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^^^^
@ -193,7 +193,7 @@ LL | const IF: i32 = if true { 5 } else { 6 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:71:25
--> $DIR/feature-gate-const-if-match.rs:70:25
|
LL | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -202,7 +202,7 @@ LL | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:74:24
--> $DIR/feature-gate-const-if-match.rs:73:24
|
LL | const MATCH: i32 = match 0 { 1 => 2, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -211,7 +211,7 @@ LL | const MATCH: i32 = match 0 { 1 => 2, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:79:21
--> $DIR/feature-gate-const-if-match.rs:78:21
|
LL | const IF: i32 = if true { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^^^^
@ -220,7 +220,7 @@ LL | const IF: i32 = if true { 5 } else { 6 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `if` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:82:25
--> $DIR/feature-gate-const-if-match.rs:81:25
|
LL | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -229,7 +229,7 @@ LL | const IF_LET: i32 = if let Some(true) = None { 5 } else { 6 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0658]: `match` is not allowed in a `const`
--> $DIR/feature-gate-const-if-match.rs:85:24
--> $DIR/feature-gate-const-if-match.rs:84:24
|
LL | const MATCH: i32 = match 0 { 1 => 2, _ => 0 };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -238,7 +238,7 @@ LL | const MATCH: i32 = match 0 { 1 => 2, _ => 0 };
= help: add `#![feature(const_if_match)]` to the crate attributes to enable
error[E0019]: constant contains unimplemented expression type
--> $DIR/feature-gate-const-if-match.rs:115:21
--> $DIR/feature-gate-const-if-match.rs:114:21
|
LL | if let Some(x) = Some(x) { x } else { 1 }
| ^

1
src/test/ui/consts/control-flow/short-circuit-let.rs
View file

@ -4,7 +4,6 @@
#![feature(const_if_match)]
#![feature(const_panic)]
#![feature(const_fn)]
const X: i32 = {
let mut x = 0;

2
src/test/ui/consts/control-flow/single_variant_match_ice.rs
View file

@ -1,6 +1,6 @@
// check-pass
#![feature(const_if_match, const_fn)]
#![feature(const_if_match)]
enum Foo {
Prob,

10
src/test/ui/internal/internal-unstable-const.rs Normal file
View file

@ -0,0 +1,10 @@
#![feature(staged_api)]
#![feature(const_if_match)]
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "rust1", since = "1.0.0")]
const fn foo() -> i32 {
if true { 4 } else { 5 } //~ loops and conditional expressions are not stable in const fn
}
fn main() {}

12
src/test/ui/internal/internal-unstable-const.stderr Normal file
View file

@ -0,0 +1,12 @@
error[E0723]: loops and conditional expressions are not stable in const fn
--> $DIR/internal-unstable-const.rs:7:5
|
LL | if true { 4 } else { 5 }
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, see issue https://github.com/rust-lang/rust/issues/57563
= help: add `#![feature(const_fn)]` to the crate attributes to enable
error: aborting due to previous error
For more information about this error, try `rustc --explain E0723`.