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Auto merge of rust-lang#129759 - dingxiangfei2009:stabilize-const-ref…
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…s-to-static, r=RalfJung

Stabilize `const_refs_to_static`

Meanwhile, I am cooking a sub-section in the language reference.
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bors committed Sep 26, 2024
2 parents f2becdf + 1576a6d commit 4428a05
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Showing 45 changed files with 157 additions and 442 deletions.
1 change: 0 additions & 1 deletion compiler/rustc_const_eval/src/check_consts/check.rs
Original file line number Diff line number Diff line change
Expand Up @@ -317,7 +317,6 @@ impl<'mir, 'tcx> Checker<'mir, 'tcx> {
{
self.error_emitted = Some(guar);
}
self.check_op_spanned(ops::StaticAccess, span)
}

/// Returns whether this place can possibly escape the evaluation of the current const/static
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28 changes: 0 additions & 28 deletions compiler/rustc_const_eval/src/check_consts/ops.rs
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,6 @@ use rustc_middle::ty::{
suggest_constraining_type_param,
};
use rustc_middle::util::{CallDesugaringKind, CallKind, call_kind};
use rustc_session::parse::feature_err;
use rustc_span::symbol::sym;
use rustc_span::{BytePos, Pos, Span, Symbol};
use rustc_trait_selection::traits::SelectionContext;
Expand Down Expand Up @@ -477,33 +476,6 @@ impl<'tcx> NonConstOp<'tcx> for RawPtrToIntCast {
}
}

/// An access to a (non-thread-local) `static`.
#[derive(Debug)]
pub(crate) struct StaticAccess;
impl<'tcx> NonConstOp<'tcx> for StaticAccess {
fn status_in_item(&self, ccx: &ConstCx<'_, 'tcx>) -> Status {
if let hir::ConstContext::Static(_) = ccx.const_kind() {
Status::Allowed
} else {
Status::Unstable(sym::const_refs_to_static)
}
}

#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
fn build_error(&self, ccx: &ConstCx<'_, 'tcx>, span: Span) -> Diag<'tcx> {
let mut err = feature_err(
&ccx.tcx.sess,
sym::const_refs_to_static,
span,
format!("referencing statics in {}s is unstable", ccx.const_kind(),),
);
err
.note("`static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.")
.help("to fix this, the value can be extracted to a `const` and then used.");
err
}
}

/// An access to a thread-local `static`.
#[derive(Debug)]
pub(crate) struct ThreadLocalAccess;
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2 changes: 1 addition & 1 deletion compiler/rustc_error_codes/src/error_codes/E0013.md
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ variable cannot refer to a static variable.

Erroneous code example:

```compile_fail,E0658
```
static X: i32 = 42;
const Y: i32 = X;
```
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2 changes: 2 additions & 0 deletions compiler/rustc_feature/src/accepted.rs
Original file line number Diff line number Diff line change
Expand Up @@ -151,6 +151,8 @@ declare_features! (
(accepted, const_raw_ptr_deref, "1.58.0", Some(51911)),
/// Allows references to types with interior mutability within constants
(accepted, const_refs_to_cell, "CURRENT_RUSTC_VERSION", Some(80384)),
/// Allows creating pointers and references to `static` items in constants.
(accepted, const_refs_to_static, "CURRENT_RUSTC_VERSION", Some(119618)),
/// Allows implementing `Copy` for closures where possible (RFC 2132).
(accepted, copy_closures, "1.26.0", Some(44490)),
/// Allows `crate` in paths.
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2 changes: 0 additions & 2 deletions compiler/rustc_feature/src/unstable.rs
Original file line number Diff line number Diff line change
Expand Up @@ -407,8 +407,6 @@ declare_features! (
(unstable, const_for, "1.56.0", Some(87575)),
/// Be more precise when looking for live drops in a const context.
(unstable, const_precise_live_drops, "1.46.0", Some(73255)),
/// Allows creating pointers and references to `static` items in constants.
(unstable, const_refs_to_static, "1.78.0", Some(119618)),
/// Allows `impl const Trait for T` syntax.
(unstable, const_trait_impl, "1.42.0", Some(67792)),
/// Allows the `?` operator in const contexts.
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2 changes: 0 additions & 2 deletions src/tools/tidy/src/issues.txt
Original file line number Diff line number Diff line change
Expand Up @@ -764,7 +764,6 @@ ui/consts/issue-46553.rs
ui/consts/issue-47789.rs
ui/consts/issue-50439.rs
ui/consts/issue-52023-array-size-pointer-cast.rs
ui/consts/issue-52060.rs
ui/consts/issue-54224.rs
ui/consts/issue-54348.rs
ui/consts/issue-54387.rs
Expand Down Expand Up @@ -3830,7 +3829,6 @@ ui/stability-attribute/issue-28388-3.rs
ui/stability-attribute/issue-99286-stable-intrinsics.rs
ui/static/auxiliary/issue_24843.rs
ui/static/issue-1660.rs
ui/static/issue-18118-2.rs
ui/static/issue-18118.rs
ui/static/issue-24446.rs
ui/static/issue-24843.rs
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28 changes: 12 additions & 16 deletions tests/ui/asm/aarch64/type-check-4.rs
Original file line number Diff line number Diff line change
@@ -1,31 +1,27 @@
//@ only-aarch64
//@ compile-flags: -C target-feature=+neon
//@ build-fail

#![feature(repr_simd)]

use std::arch::aarch64::float64x2_t;
use std::arch::{asm, global_asm};

#[repr(simd)]
#[derive(Copy, Clone)]
struct Simd256bit([f64; 4]);
use std::arch::global_asm;

fn main() {}

// Constants must be... constant

static S: i32 = 1;
static mut S: i32 = 1;
const fn const_foo(x: i32) -> i32 {
x
}
const fn const_bar<T>(x: T) -> T {
x
}
global_asm!("{}", const S);
//~^ ERROR referencing statics
global_asm!("{}", const unsafe { S });
//~^ ERROR: evaluation of constant value failed
//~| mutable global memory
global_asm!("{}", const const_foo(0));
global_asm!("{}", const const_foo(S));
//~^ ERROR referencing statics
global_asm!("{}", const const_foo(unsafe { S }));
//~^ ERROR: evaluation of constant value failed
//~| mutable global memory
global_asm!("{}", const const_bar(0));
global_asm!("{}", const const_bar(S));
//~^ ERROR referencing statics
global_asm!("{}", const const_bar(unsafe { S }));
//~^ ERROR: evaluation of constant value failed
//~| mutable global memory
44 changes: 13 additions & 31 deletions tests/ui/asm/aarch64/type-check-4.stderr
Original file line number Diff line number Diff line change
@@ -1,39 +1,21 @@
error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:24:25
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:17:34
|
LL | global_asm!("{}", const S);
| ^
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const unsafe { S });
| ^ constant accesses mutable global memory

error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:27:35
|
LL | global_asm!("{}", const const_foo(S));
| ^
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:21:44
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const const_foo(unsafe { S }));
| ^ constant accesses mutable global memory

error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:30:35
|
LL | global_asm!("{}", const const_bar(S));
| ^
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:25:44
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const const_bar(unsafe { S }));
| ^ constant accesses mutable global memory

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0658`.
For more information about this error, try `rustc --explain E0080`.
2 changes: 0 additions & 2 deletions tests/ui/asm/const-refs-to-static.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,6 @@
//@ ignore-nvptx64
//@ ignore-spirv

#![feature(const_refs_to_static)]

use std::arch::{asm, global_asm};
use std::ptr::addr_of;

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4 changes: 2 additions & 2 deletions tests/ui/asm/const-refs-to-static.stderr
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: invalid type for `const` operand
--> $DIR/const-refs-to-static.rs:12:19
--> $DIR/const-refs-to-static.rs:10:19
|
LL | global_asm!("{}", const addr_of!(FOO));
| ^^^^^^-------------
Expand All @@ -9,7 +9,7 @@ LL | global_asm!("{}", const addr_of!(FOO));
= help: `const` operands must be of an integer type

error: invalid type for `const` operand
--> $DIR/const-refs-to-static.rs:17:25
--> $DIR/const-refs-to-static.rs:15:25
|
LL | unsafe { asm!("{}", const addr_of!(FOO)) };
| ^^^^^^-------------
Expand Down
23 changes: 12 additions & 11 deletions tests/ui/asm/x86_64/type-check-4.rs
Original file line number Diff line number Diff line change
@@ -1,26 +1,27 @@
//@ only-x86_64
//@ compile-flags: -C target-feature=+avx512f
//@ build-fail

use std::arch::{asm, global_asm};

use std::arch::x86_64::{_mm256_setzero_ps, _mm_setzero_ps};
use std::arch::global_asm;

fn main() {}

// Constants must be... constant

static S: i32 = 1;
static mut S: i32 = 1;
const fn const_foo(x: i32) -> i32 {
x
}
const fn const_bar<T>(x: T) -> T {
x
}
global_asm!("{}", const S);
//~^ ERROR referencing statics
global_asm!("{}", const unsafe { S });
//~^ ERROR evaluation of constant value failed
//~| mutable global memory
global_asm!("{}", const const_foo(0));
global_asm!("{}", const const_foo(S));
//~^ ERROR referencing statics
global_asm!("{}", const const_foo(unsafe { S }));
//~^ ERROR evaluation of constant value failed
//~| mutable global memory
global_asm!("{}", const const_bar(0));
global_asm!("{}", const const_bar(S));
//~^ ERROR referencing statics
global_asm!("{}", const const_bar(unsafe { S }));
//~^ ERROR evaluation of constant value failed
//~| mutable global memory
44 changes: 13 additions & 31 deletions tests/ui/asm/x86_64/type-check-4.stderr
Original file line number Diff line number Diff line change
@@ -1,39 +1,21 @@
error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:19:25
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:17:34
|
LL | global_asm!("{}", const S);
| ^
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const unsafe { S });
| ^ constant accesses mutable global memory

error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:22:35
|
LL | global_asm!("{}", const const_foo(S));
| ^
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:21:44
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const const_foo(unsafe { S }));
| ^ constant accesses mutable global memory

error[E0658]: referencing statics in constants is unstable
--> $DIR/type-check-4.rs:25:35
|
LL | global_asm!("{}", const const_bar(S));
| ^
error[E0080]: evaluation of constant value failed
--> $DIR/type-check-4.rs:25:44
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.
LL | global_asm!("{}", const const_bar(unsafe { S }));
| ^ constant accesses mutable global memory

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0658`.
For more information about this error, try `rustc --explain E0080`.
2 changes: 0 additions & 2 deletions tests/ui/consts/const-fn-not-safe-for-const.rs
Original file line number Diff line number Diff line change
Expand Up @@ -18,12 +18,10 @@ static Y: u32 = 0;

const fn get_Y() -> u32 {
Y
//~^ ERROR referencing statics in constant functions
}

const fn get_Y_addr() -> &'static u32 {
&Y
//~^ ERROR referencing statics in constant functions
}

const fn get() -> u32 {
Expand Down
29 changes: 2 additions & 27 deletions tests/ui/consts/const-fn-not-safe-for-const.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -6,31 +6,6 @@ LL | random()
|
= note: calls in constant functions are limited to constant functions, tuple structs and tuple variants

error[E0658]: referencing statics in constant functions is unstable
--> $DIR/const-fn-not-safe-for-const.rs:20:5
|
LL | Y
| ^
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.

error[E0658]: referencing statics in constant functions is unstable
--> $DIR/const-fn-not-safe-for-const.rs:25:6
|
LL | &Y
| ^
|
= note: see issue #119618 <https://github.com/rust-lang/rust/issues/119618> for more information
= help: add `#![feature(const_refs_to_static)]` to the crate attributes to enable
= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
= note: `static` and `const` variables can refer to other `const` variables. A `const` variable, however, cannot refer to a `static` variable.
= help: to fix this, the value can be extracted to a `const` and then used.

error: aborting due to 3 previous errors
error: aborting due to 1 previous error

Some errors have detailed explanations: E0015, E0658.
For more information about an error, try `rustc --explain E0015`.
For more information about this error, try `rustc --explain E0015`.
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
//@ normalize-stderr-test: "(the raw bytes of the constant) \(size: [0-9]*, align: [0-9]*\)" -> "$1 (size: $$SIZE, align: $$ALIGN)"
//@ normalize-stderr-test: "( 0x[0-9a-f][0-9a-f] │)? ([0-9a-f][0-9a-f] |__ |╾─*ALLOC[0-9]+(\+[a-z0-9]+)?(<imm>)?─*╼ )+ *│.*" -> " HEX_DUMP"
//@ normalize-stderr-test: "HEX_DUMP\s*\n\s*HEX_DUMP" -> "HEX_DUMP"
#![feature(const_refs_to_static)]

use std::sync::Mutex;

Expand Down
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