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Rollup merge of #77160 - ecstatic-morse:const-fn-transmute-suggestion, r=oli-obk

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Suggest `const_fn_transmute`, not `const_fn`

More fallout from #76850 in the vein of #77134. The fix is the same. I looked through the structured errors file and didn't see any more of this kind of diagnostics bug.

r? @oli-obk
This commit is contained in:
Jonas Schievink 2020-09-25 02:29:49 +02:00 • committed by GitHub
commit b8d158b0f8
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5 changed files with 60 additions and 43 deletions
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9
compiler/rustc_mir/src/transform/check_consts/ops.rs
View file

@ -489,7 +489,14 @@ impl NonConstOp for Transmute {
} }
fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) { fn emit_error(&self, ccx: &ConstCx<'_, '_>, span: Span) {
mcf_emit_error(ccx, span, "can only call `transmute` from const items, not `const fn`"); feature_err(
&ccx.tcx.sess.parse_sess,
sym::const_fn_transmute,
span,
&format!("`transmute` is not allowed in {}s", ccx.const_kind()),
)
.note("`transmute` is only allowed in constants and statics for now")
.emit();
} }
} }

18
src/test/ui/feature-gates/feature-gate-const_fn_transmute.rs
View file

@ -6,33 +6,33 @@ struct Foo(u32);
const TRANSMUTED_U32: u32 = unsafe { mem::transmute(Foo(3)) }; const TRANSMUTED_U32: u32 = unsafe { mem::transmute(Foo(3)) };
const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } } const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } } const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } } const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) } const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) } const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) } const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) } const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
//~| ERROR call to unsafe function is unsafe and requires unsafe function or block //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) } const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
//~| ERROR call to unsafe function is unsafe and requires unsafe function or block //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) } const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
//~^ ERROR can only call `transmute` from const items, not `const fn` //~^ ERROR `transmute`
//~| ERROR call to unsafe function is unsafe and requires unsafe function or block //~| ERROR call to unsafe function is unsafe and requires unsafe function or block
fn main() {} fn main() {}

65
src/test/ui/feature-gates/feature-gate-const_fn_transmute.stderr
View file

@ -1,83 +1,92 @@
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:8:43 --> $DIR/feature-gate-const_fn_transmute.rs:8:43
| |
LL | const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } } LL | const fn transmute_fn() -> u32 { unsafe { mem::transmute(Foo(3)) } }
| ^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:11:53 --> $DIR/feature-gate-const_fn_transmute.rs:11:53
| |
LL | const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } } LL | const fn transmute_fn_intrinsic() -> u32 { unsafe { std::intrinsics::transmute(Foo(3)) } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:14:58 --> $DIR/feature-gate-const_fn_transmute.rs:14:58
| |
LL | const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } } LL | const fn transmute_fn_core_intrinsic() -> u32 { unsafe { core::intrinsics::transmute(Foo(3)) } }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:17:48 --> $DIR/feature-gate-const_fn_transmute.rs:17:48
| |
LL | const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) } LL | const unsafe fn unsafe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:20:58 --> $DIR/feature-gate-const_fn_transmute.rs:20:58
| |
LL | const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) } LL | const unsafe fn unsafe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:23:63 --> $DIR/feature-gate-const_fn_transmute.rs:23:63
| |
LL | const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) } LL | const unsafe fn unsafe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:26:39 --> $DIR/feature-gate-const_fn_transmute.rs:26:39
| |
LL | const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) } LL | const fn safe_transmute_fn() -> u32 { mem::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:30:49 --> $DIR/feature-gate-const_fn_transmute.rs:30:49
| |
LL | const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) } LL | const fn safe_transmute_fn_intrinsic() -> u32 { std::intrinsics::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/feature-gate-const_fn_transmute.rs:34:54 --> $DIR/feature-gate-const_fn_transmute.rs:34:54
| |
LL | const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) } LL | const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::transmute(Foo(3)) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error[E0133]: call to unsafe function is unsafe and requires unsafe function or block error[E0133]: call to unsafe function is unsafe and requires unsafe function or block
--> $DIR/feature-gate-const_fn_transmute.rs:26:39 --> $DIR/feature-gate-const_fn_transmute.rs:26:39
@ -105,5 +114,5 @@ LL | const fn safe_transmute_fn_core_intrinsic() -> u32 { core::intrinsics::tran
error: aborting due to 12 previous errors error: aborting due to 12 previous errors
Some errors have detailed explanations: E0133, E0723. Some errors have detailed explanations: E0133, E0658.
For more information about an error, try `rustc --explain E0133`. For more information about an error, try `rustc --explain E0133`.

2
src/test/ui/internal/internal-unstable-const.rs
View file

@ -8,7 +8,7 @@
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "rust1", since = "1.0.0")] #[rustc_const_stable(feature = "rust1", since = "1.0.0")]
pub const fn foo() -> i32 { pub const fn foo() -> i32 {
unsafe { std::mem::transmute(4u32) } //~ ERROR can only call `transmute` from const items unsafe { std::mem::transmute(4u32) } //~ ERROR `transmute`
} }
fn main() {} fn main() {}

9
src/test/ui/internal/internal-unstable-const.stderr
View file

@ -1,12 +1,13 @@
error[E0723]: can only call `transmute` from const items, not `const fn` error[E0658]: `transmute` is not allowed in constant functions
--> $DIR/internal-unstable-const.rs:11:14 --> $DIR/internal-unstable-const.rs:11:14
| |
LL | unsafe { std::mem::transmute(4u32) } LL | unsafe { std::mem::transmute(4u32) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^
| |
= note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information = note: see issue #53605 <https://github.com/rust-lang/rust/issues/53605> for more information
= help: add `#![feature(const_fn)]` to the crate attributes to enable = help: add `#![feature(const_fn_transmute)]` to the crate attributes to enable
= note: `transmute` is only allowed in constants and statics for now
error: aborting due to previous error error: aborting due to previous error
For more information about this error, try `rustc --explain E0723`. For more information about this error, try `rustc --explain E0658`.