Auto merge of #85109 - RalfJung:remove-const_fn, r=oli-obk

remove const_fn feature gate

Fixes #84510
r? `@oli-obk`

Author: bors

compiler/rustc_feature/src/active.rs

@@ -274,9 +274,6 @@ declare_features! (
     /// Allows using non lexical lifetimes (RFC 2094).
     (active, nll, "1.0.0", Some(43234), None),
 
-    /// Allows the definition of `const` functions with some advanced features.
-    (active, const_fn, "1.2.0", Some(57563), None),
-
     /// Allows associated type defaults.
     (active, associated_type_defaults, "1.2.0", Some(29661), None),
 

compiler/rustc_feature/src/removed.rs

@@ -136,6 +136,9 @@ declare_features! (
     (removed, main, "1.53.0", Some(29634), None, None),
     (removed, pub_macro_rules, "1.53.0", Some(78855), None,
      Some("removed due to being incomplete, in particular it does not work across crates")),
+     /// Allows the definition of `const` functions with some advanced features.
+    (removed, const_fn, "1.54.0", Some(57563), None,
+     Some("split into finer-grained feature gates")),
 
     // -------------------------------------------------------------------------
     // feature-group-end: removed features

library/std/src/lib.rs

@@ -246,7 +246,6 @@
 #![feature(const_cstr_unchecked)]
 #![feature(const_fn_floating_point_arithmetic)]
 #![feature(const_fn_transmute)]
-#![feature(const_fn)]
 #![feature(const_fn_fn_ptr_basics)]
 #![feature(const_io_structs)]
 #![feature(const_ip)]

src/ci/pgo.sh

@@ -12,7 +12,7 @@ RUSTC_BOOTSTRAP=1 ./build/$PGO_HOST/stage2/bin/rustc --edition=2018 \
 
 # Download and build a single-file stress test benchmark on perf.rust-lang.org.
 function pgo_perf_benchmark {
-    local PERF=9442def56a39d742bf27ebcc3e0614cf117e1bc2
+    local PERF=1e19fc4c6168d2f7596e512f42f358f245d8f09d
     local github_prefix=https://raw.githubusercontent.com/rust-lang/rustc-perf/$PERF
     local name=$1
     curl -o /tmp/$name.rs $github_prefix/collector/benchmarks/$name/src/lib.rs

src/doc/unstable-book/src/language-features/const-fn.md

@@ -1,7 +1,5 @@
 // Test internal const fn feature gate.
 
-#![feature(const_fn)]
-
 #[rustc_const_unstable(feature="fzzzzzt")] //~ stability attributes may not be used outside
 pub const fn bazinga() {}
 

src/test/ui/feature-gates/feature-gate-const_fn.rs

@@ -1,5 +1,5 @@
 error[E0734]: stability attributes may not be used outside of the standard library
-  --> $DIR/feature-gate-rustc_const_unstable.rs:5:1
+  --> $DIR/feature-gate-rustc_const_unstable.rs:3:1
    |
 LL | #[rustc_const_unstable(feature="fzzzzzt")]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

src/test/ui/feature-gates/feature-gate-const_fn.stderr

@@ -3,7 +3,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #![feature(staged_api)]
-#![feature(const_transmute, const_fn)]
+#![feature(const_transmute)]
 
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_const_stable(feature = "rust1", since = "1.0.0")]

src/test/ui/feature-gates/feature-gate-rustc_const_unstable.rs

@@ -1,5 +1,3 @@
-#![feature(const_fn)]
-
 const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
 //~^ ERROR type annotations needed
 

src/test/ui/feature-gates/feature-gate-rustc_const_unstable.stderr

@@ -1,11 +1,11 @@
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/issue-54954.rs:7:5
+  --> $DIR/issue-54954.rs:5:5
    |
 LL |     const fn const_val<T: Sized>() -> usize {
    |     ^^^^^ functions in traits cannot be const
 
 error[E0283]: type annotations needed
-  --> $DIR/issue-54954.rs:3:24
+  --> $DIR/issue-54954.rs:1:24
    |
 LL | const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type

src/test/ui/internal/internal-unstable-const.rs

@@ -1,5 +1,3 @@
-#![feature(const_fn)]
-
 trait Foo {
     fn f() -> u32;
     const fn g(); //~ ERROR cannot be declared const

src/test/ui/issues/issue-54954.rs

@@ -1,11 +1,11 @@
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/const-fn-in-trait.rs:5:5
+  --> $DIR/const-fn-in-trait.rs:3:5
    |
 LL |     const fn g();
    |     ^^^^^ functions in traits cannot be const
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/const-fn-in-trait.rs:9:5
+  --> $DIR/const-fn-in-trait.rs:7:5
    |
 LL |     const fn f() -> u32 { 22 }
    |     ^^^^^ functions in traits cannot be const

src/test/ui/issues/issue-54954.stderr

@@ -3,7 +3,6 @@
 // edition:2018
 
 #![feature(const_extern_fn)]
-#![feature(const_fn)]
 
 fn main() {
     async fn ff1() {} // OK.

src/test/ui/mismatched_types/const-fn-in-trait.rs

@@ -1,5 +1,5 @@
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:13:5
+  --> $DIR/fn-header-semantic-fail.rs:12:5
    |
 LL |     const async unsafe extern "C" fn ff5() {} // OK.
    |     ^^^^^-^^^^^------------------------------
@@ -8,7 +8,7 @@ LL |     const async unsafe extern "C" fn ff5() {} // OK.
    |     `const` because of this
 
 error[E0706]: functions in traits cannot be declared `async`
-  --> $DIR/fn-header-semantic-fail.rs:17:9
+  --> $DIR/fn-header-semantic-fail.rs:16:9
    |
 LL |         async fn ft1();
    |         -----^^^^^^^^^^
@@ -19,19 +19,19 @@ LL |         async fn ft1();
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:19:9
+  --> $DIR/fn-header-semantic-fail.rs:18:9
    |
 LL |         const fn ft3();
    |         ^^^^^ functions in traits cannot be const
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:21:9
+  --> $DIR/fn-header-semantic-fail.rs:20:9
    |
 LL |         const async unsafe extern "C" fn ft5();
    |         ^^^^^ functions in traits cannot be const
 
 error[E0706]: functions in traits cannot be declared `async`
-  --> $DIR/fn-header-semantic-fail.rs:21:9
+  --> $DIR/fn-header-semantic-fail.rs:20:9
    |
 LL |         const async unsafe extern "C" fn ft5();
    |         ^^^^^^-----^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -42,7 +42,7 @@ LL |         const async unsafe extern "C" fn ft5();
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:21:9
+  --> $DIR/fn-header-semantic-fail.rs:20:9
    |
 LL |         const async unsafe extern "C" fn ft5();
    |         ^^^^^-^^^^^----------------------------
@@ -51,7 +51,7 @@ LL |         const async unsafe extern "C" fn ft5();
    |         `const` because of this
 
 error[E0706]: functions in traits cannot be declared `async`
-  --> $DIR/fn-header-semantic-fail.rs:29:9
+  --> $DIR/fn-header-semantic-fail.rs:28:9
    |
 LL |         async fn ft1() {}
    |         -----^^^^^^^^^^^^
@@ -62,19 +62,19 @@ LL |         async fn ft1() {}
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:32:9
+  --> $DIR/fn-header-semantic-fail.rs:31:9
    |
 LL |         const fn ft3() {}
    |         ^^^^^ functions in traits cannot be const
 
 error[E0379]: functions in traits cannot be declared const
-  --> $DIR/fn-header-semantic-fail.rs:34:9
+  --> $DIR/fn-header-semantic-fail.rs:33:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^ functions in traits cannot be const
 
 error[E0706]: functions in traits cannot be declared `async`
-  --> $DIR/fn-header-semantic-fail.rs:34:9
+  --> $DIR/fn-header-semantic-fail.rs:33:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^^-----^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -85,7 +85,7 @@ LL |         const async unsafe extern "C" fn ft5() {}
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:34:9
+  --> $DIR/fn-header-semantic-fail.rs:33:9
    |
 LL |         const async unsafe extern "C" fn ft5() {}
    |         ^^^^^-^^^^^------------------------------
@@ -94,7 +94,7 @@ LL |         const async unsafe extern "C" fn ft5() {}
    |         `const` because of this
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:46:9
+  --> $DIR/fn-header-semantic-fail.rs:45:9
    |
 LL |         const async unsafe extern "C" fn fi5() {}
    |         ^^^^^-^^^^^------------------------------
@@ -103,7 +103,7 @@ LL |         const async unsafe extern "C" fn fi5() {}
    |         `const` because of this
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:51:18
+  --> $DIR/fn-header-semantic-fail.rs:50:18
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -116,7 +116,7 @@ LL |         fn fe1();
    |         ^^
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:52:19
+  --> $DIR/fn-header-semantic-fail.rs:51:19
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -130,7 +130,7 @@ LL |         fn fe2();
    |         ^^
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:53:18
+  --> $DIR/fn-header-semantic-fail.rs:52:18
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -144,7 +144,7 @@ LL |         fn fe3();
    |         ^^
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:54:23
+  --> $DIR/fn-header-semantic-fail.rs:53:23
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -158,7 +158,7 @@ LL |         fn fe4();
    |         ^^
 
 error: functions in `extern` blocks cannot have qualifiers
-  --> $DIR/fn-header-semantic-fail.rs:55:42
+  --> $DIR/fn-header-semantic-fail.rs:54:42
    |
 LL |     extern "C" {
    |     ---------- in this `extern` block
@@ -172,7 +172,7 @@ LL |         fn fe5();
    |         ^^
 
 error: functions cannot be both `const` and `async`
-  --> $DIR/fn-header-semantic-fail.rs:55:9
+  --> $DIR/fn-header-semantic-fail.rs:54:9
    |
 LL |         const async unsafe extern "C" fn fe5();
    |         ^^^^^-^^^^^----------------------------
@@ -181,7 +181,7 @@ LL |         const async unsafe extern "C" fn fe5();
    |         `const` because of this
 
 error[E0053]: method `ft1` has an incompatible type for trait
-  --> $DIR/fn-header-semantic-fail.rs:29:24
+  --> $DIR/fn-header-semantic-fail.rs:28:24
    |
 LL |         async fn ft1();
    |                       - type in trait
@@ -197,7 +197,7 @@ LL |         async fn ft1() {}
               found fn pointer `fn() -> impl Future`
 
 error[E0053]: method `ft5` has an incompatible type for trait
-  --> $DIR/fn-header-semantic-fail.rs:34:48
+  --> $DIR/fn-header-semantic-fail.rs:33:48
    |
 LL |         const async unsafe extern "C" fn ft5();
    |                                               - type in trait

src/test/ui/mismatched_types/const-fn-in-trait.stderr

@@ -6,7 +6,7 @@
 // run-pass
 // compile-flags: -Z unleash-the-miri-inside-of-you
 
-#![feature(core_intrinsics, const_caller_location, const_fn)]
+#![feature(core_intrinsics, const_caller_location)]
 
 type L = &'static std::panic::Location<'static>;
 

src/test/ui/parser/fn-header-semantic-fail.rs

@@ -2,7 +2,7 @@
 // revisions: default mir-opt
 //[mir-opt] compile-flags: -Zmir-opt-level=4
 
-#![feature(const_caller_location, const_fn)]
+#![feature(const_caller_location)]
 
 use std::panic::Location;
 

src/test/ui/parser/fn-header-semantic-fail.stderr

@@ -1,4 +1,4 @@
-#![feature(rustc_attrs, const_fn)]
+#![feature(rustc_attrs)]
 
 #[rustc_args_required_const(0)]
 fn foo(_a: i32) {

src/test/ui/rfc-2091-track-caller/caller-location-fnptr-rt-ctfe-equiv.rs

@@ -1,6 +1,6 @@
 // Various checks that stability attributes are used correctly, per RFC 507
 
-#![feature(const_fn, staged_api)]
+#![feature(staged_api)]
 
 #![stable(feature = "rust1", since = "1.0.0")]
 

src/test/ui/rfc-2091-track-caller/const-caller-location.rs

@@ -1,5 +1,3 @@
-#![feature(const_fn)]
-
 struct WithDtor;
 
 impl Drop for WithDtor {