Rollup merge of #138632 - clubby789:stabilize-cfg-boolean-lit, r=davidtwco,Urgau,traviscross

Stabilize `cfg_boolean_literals`

Closes #131204
`@rustbot` labels +T-lang +I-lang-nominated
This will end up conflicting with the test in #138293 so whichever doesn't land first will need updating

--

# Stabilization Report

## General design

### What is the RFC for this feature and what changes have occurred to the user-facing design since the RFC was finalized?

[RFC 3695](https://github.com/rust-lang/rfcs/pull/3695), none.

### What behavior are we committing to that has been controversial? Summarize the major arguments pro/con.

None

### Are there extensions to this feature that remain unstable? How do we know that we are not accidentally committing to those?

None

## Has a call-for-testing period been conducted? If so, what feedback was received?

Yes; only positive feedback was received.

## Implementation quality

### Summarize the major parts of the implementation and provide links into the code (or to PRs)

Implemented in [#131034](https://github.com/rust-lang/rust/pull/131034).

### Summarize existing test coverage of this feature

- [Basic usage, including `#[cfg()]`, `cfg!()` and `#[cfg_attr()]`](6d71251cf9/tests/ui/cfg/true-false.rs)
- [`--cfg=true/false` on the command line being accessible via `r#true/r#false`](6d71251cf9/tests/ui/cfg/raw-true-false.rs)
- [Interaction with the unstable `#[doc(cfg(..))]` feature](6d71251/tests/rustdoc-ui/cfg-boolean-literal.rs)
- [Denying `--check-cfg=cfg(true/false)`](6d71251/tests/ui/check-cfg/invalid-arguments.rs)
- Ensuring `--cfg false` on the command line doesn't change the meaning of `cfg(false)`: `tests/ui/cfg/cmdline-false.rs`
- Ensuring both `cfg(true)` and `cfg(false)` on the same item result in it being disabled: `tests/ui/cfg/both-true-false.rs`

### What outstanding bugs in the issue tracker involve this feature? Are they stabilization-blocking?

The above mentioned issue; it should not block as it interacts with another unstable feature.

### What FIXMEs are still in the code for that feature and why is it ok to leave them there?

None

### Summarize contributors to the feature by name for recognition and assuredness that people involved in the feature agree with stabilization
- `@clubby789` (RFC)
- `@Urgau` (Implementation in rustc)

### Which tools need to be adjusted to support this feature. Has this work been done?

`rustdoc`'s  unstable`#[doc(cfg(..)]` has been updated to respect it. `cargo` has been updated with a forward compatibility lint to enable supporting it in cargo once stabilized.

## Type system and execution rules

### What updates are needed to the reference/specification? (link to PRs when they exist)

A few lines to be added to the reference for configuration predicates, specified in the RFC.

compiler/rustc_attr_parsing/src/attributes/cfg.rs

@@ -7,7 +7,6 @@ use rustc_session::config::ExpectedValues;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::UNEXPECTED_CFGS;
 use rustc_session::parse::feature_err;
-use rustc_span::symbol::kw;
 use rustc_span::{Span, Symbol, sym};
 
 use crate::session_diagnostics::{self, UnsupportedLiteralReason};
@@ -89,20 +88,6 @@ pub fn eval_condition(
     let cfg = match cfg {
         MetaItemInner::MetaItem(meta_item) => meta_item,
         MetaItemInner::Lit(MetaItemLit { kind: LitKind::Bool(b), .. }) => {
-            if let Some(features) = features {
-                // we can't use `try_gate_cfg` as symbols don't differentiate between `r#true`
-                // and `true`, and we want to keep the former working without feature gate
-                gate_cfg(
-                    &(
-                        if *b { kw::True } else { kw::False },
-                        sym::cfg_boolean_literals,
-                        |features: &Features| features.cfg_boolean_literals(),
-                    ),
-                    cfg.span(),
-                    sess,
-                    features,
-                );
-            }
             return *b;
         }
         _ => {

compiler/rustc_feature/src/accepted.rs

@@ -95,6 +95,8 @@ declare_features! (
     (accepted, c_unwind, "1.81.0", Some(74990)),
     /// Allows `#[cfg_attr(predicate, multiple, attributes, here)]`.
     (accepted, cfg_attr_multi, "1.33.0", Some(54881)),
+    /// Allows the use of `#[cfg(<true/false>)]`.
+    (accepted, cfg_boolean_literals, "CURRENT_RUSTC_VERSION", Some(131204)),
     /// Allows the use of `#[cfg(doctest)]`, set when rustdoc is collecting doctests.
     (accepted, cfg_doctest, "1.40.0", Some(62210)),
     /// Enables `#[cfg(panic = "...")]` config key.

compiler/rustc_feature/src/unstable.rs

@@ -391,8 +391,6 @@ declare_features! (
     (unstable, async_trait_bounds, "1.85.0", Some(62290)),
     /// Allows using C-variadics.
     (unstable, c_variadic, "1.34.0", Some(44930)),
-    /// Allows the use of `#[cfg(<true/false>)]`.
-    (unstable, cfg_boolean_literals, "1.83.0", Some(131204)),
     /// Allows the use of `#[cfg(contract_checks)` to check if contract checks are enabled.
     (unstable, cfg_contract_checks, "1.86.0", Some(128044)),
     /// Allows the use of `#[cfg(overflow_checks)` to check if integer overflow behaviour.

src/doc/unstable-book/src/language-features/cfg-boolean-literals.md

@@ -1,22 +0,0 @@
-# `cfg_boolean_literals`
-
-The tracking issue for this feature is: [#131204]
-
-[#131204]: https://github.com/rust-lang/rust/issues/131204
-
-------------------------
-
-The `cfg_boolean_literals` feature makes it possible to use the `true`/`false`
-literal as cfg predicate. They always evaluate to true/false respectively.
-
-## Examples
-
-```rust
-#![feature(cfg_boolean_literals)]
-
-#[cfg(true)]
-const A: i32 = 5;
-
-#[cfg(all(false))]
-const A: i32 = 58 * 89;
-```

src/tools/rust-analyzer/crates/ide-db/src/generated/lints.rs

@@ -3789,35 +3789,6 @@ The tracking issue for this feature is: [#64797]
 [#64797]: https://github.com/rust-lang/rust/issues/64797
 
 ------------------------
-"##,
-        default_severity: Severity::Allow,
-        warn_since: None,
-        deny_since: None,
-    },
-    Lint {
-        label: "cfg_boolean_literals",
-        description: r##"# `cfg_boolean_literals`
-
-The tracking issue for this feature is: [#131204]
-
-[#131204]: https://github.com/rust-lang/rust/issues/131204
-
-------------------------
-
-The `cfg_boolean_literals` feature makes it possible to use the `true`/`false`
-literal as cfg predicate. They always evaluate to true/false respectively.
-
-## Examples
-
-```rust
-#![feature(cfg_boolean_literals)]
-
-#[cfg(true)]
-const A: i32 = 5;
-
-#[cfg(all(false))]
-const A: i32 = 58 * 89;
-```
 "##,
         default_severity: Severity::Allow,
         warn_since: None,

tests/pretty/ast-stmt-expr-attr.rs

@@ -2,7 +2,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn syntax() {
     let _ = #[attr] [];
     let _ = #[attr] [0];

tests/pretty/enum-variant-vis.rs

@@ -4,5 +4,5 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 enum Foo { pub V, }

tests/pretty/if-attr.rs

@@ -1,6 +1,6 @@
 //@ pp-exact
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn simple_attr() {
 
     #[attr]
@@ -10,21 +10,21 @@ fn simple_attr() {
     if true {}
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn if_else_chain() {
 
     #[first_attr]
     if true {} else if false {} else {}
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn if_let() {
 
     #[attr]
     if let Some(_) = Some(true) {}
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn let_attr_if() {
     let _ = #[attr] if let _ = 0 {};
     let _ = #[attr] if true {};

tests/pretty/nested-item-vis-defaultness.rs

@@ -4,7 +4,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 extern "C" {
     static X: u8;
     type X;
@@ -14,7 +14,7 @@ extern "C" {
     pub fn foo();
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 trait T {
     const X: u8;
     type X;
@@ -30,7 +30,7 @@ trait T {
     pub default fn foo();
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 impl T for S {
     const X: u8;
     type X;

tests/rustdoc-ui/cfg-boolean-literal.rs

@@ -1,6 +1,5 @@
 //@ check-pass
 
-#![feature(cfg_boolean_literals)]
 #![feature(doc_cfg)]
 
 #[doc(cfg(false))]

tests/rustdoc-ui/doc-cfg-unstable.rs

@@ -1,10 +1,6 @@
 // #138113: rustdoc didn't gate unstable predicates inside `doc(cfg(..))`
 #![feature(doc_cfg)]
 
-// `cfg_boolean_literals`
-#[doc(cfg(false))] //~ ERROR `cfg(false)` is experimental and subject to change
-pub fn cfg_boolean_literals() {}
-
 // `cfg_version`
 #[doc(cfg(sanitize = "thread"))] //~ ERROR `cfg(sanitize)` is experimental and subject to change
 pub fn cfg_sanitize() {}

tests/rustdoc-ui/doc-cfg-unstable.stderr

@@ -1,15 +1,5 @@
-error[E0658]: `cfg(false)` is experimental and subject to change
-  --> $DIR/doc-cfg-unstable.rs:5:11
-   |
-LL | #[doc(cfg(false))]
-   |           ^^^^^
-   |
-   = note: see issue #131204 <https://github.com/rust-lang/rust/issues/131204> for more information
-   = help: add `#![feature(cfg_boolean_literals)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
 error[E0658]: `cfg(sanitize)` is experimental and subject to change
-  --> $DIR/doc-cfg-unstable.rs:9:11
+  --> $DIR/doc-cfg-unstable.rs:5:11
    |
 LL | #[doc(cfg(sanitize = "thread"))]
    |           ^^^^^^^^^^^^^^^^^^^
@@ -18,6 +8,6 @@ LL | #[doc(cfg(sanitize = "thread"))]
    = help: add `#![feature(cfg_sanitize)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0658`.

tests/ui/associated-types/associated-type-macro.rs

@@ -1,4 +1,4 @@
 fn main() {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     <() as module>::mac!(); //~ ERROR macros cannot use qualified paths
 }

tests/ui/async-await/feature-async-for-loop.rs

@@ -11,7 +11,7 @@ fn f() {
     };
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn g() {
     let _ = async {
         for await _i in core::async_iter::from_iter(0..3) {

tests/ui/async-await/no-unsafe-async.rs

@@ -3,11 +3,11 @@
 struct S;
 
 impl S {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     unsafe async fn g() {} //~ ERROR expected one of `extern` or `fn`, found keyword `async`
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 unsafe async fn f() {} //~ ERROR expected one of `extern` or `fn`, found keyword `async`
 
 fn main() {}

tests/ui/attributes/z-crate-attr/cfg-false.rs

@@ -1,5 +1,5 @@
-// Ensure that `-Z crate-attr=cfg(FALSE)` can comment out the whole crate
+// Ensure that `-Z crate-attr=cfg(false)` can comment out the whole crate
-//@ compile-flags: --crate-type=lib -Zcrate-attr=cfg(FALSE)
+//@ compile-flags: --crate-type=lib -Zcrate-attr=cfg(false)
 //@ check-pass
 
 // NOTE: duplicate items are load-bearing

tests/ui/auto-traits/pre-cfg.rs

@@ -1,6 +1,6 @@
 //@ check-pass
 
-#[cfg(FALSE)]
+#[cfg(false)]
 auto trait Foo {}
 //~^ WARN `auto` traits are unstable
 //~| WARN unstable syntax can change at any point in the future, causing a hard error!

tests/ui/cfg/auxiliary/cfg_false_lib.rs

@@ -1,4 +1,4 @@
-// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`.
+// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(false)`.
 // This crate has no such attribute, therefore this crate does link to libstd.
 
-#![cfg(FALSE)]
+#![cfg(false)]

tests/ui/cfg/auxiliary/cfg_false_lib_no_std_after.rs

@@ -1,5 +1,5 @@
-// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`.
+// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(false)`.
 // Therefore this crate does link to libstd.
 
-#![cfg(FALSE)]
+#![cfg(false)]
 #![no_std]

tests/ui/cfg/auxiliary/cfg_false_lib_no_std_before.rs

@@ -1,8 +1,8 @@
-// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(FALSE)`.
+// `#![no_std]` on a fully unconfigured crate is respected if it's placed before `cfg(false)`.
 // Therefore this crate doesn't link to libstd.
 
 //@ no-prefer-dynamic
 
 #![no_std]
 #![crate_type = "lib"]
-#![cfg(FALSE)]
+#![cfg(false)]

tests/ui/cfg/auxiliary/cfged_out.rs

@@ -1,8 +1,8 @@
 pub mod inner {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     pub fn uwu() {}
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     pub mod doesnt_exist {
         pub fn hello() {}
     }

tests/ui/cfg/both-true-false.rs

@@ -0,0 +1,14 @@
+/// Test that placing a `cfg(true)` and `cfg(false)` on the same item result in
+//. it being disabled.`
+
+#[cfg(false)]
+#[cfg(true)]
+fn foo() {}
+
+#[cfg(true)]
+#[cfg(false)]
+fn foo() {}
+
+fn main() {
+    foo();  //~ ERROR cannot find function `foo` in this scope
+}

tests/ui/cfg/both-true-false.stderr

@@ -0,0 +1,9 @@
+error[E0425]: cannot find function `foo` in this scope
+  --> $DIR/both-true-false.rs:13:5
+   |
+LL |     foo();
+   |     ^^^ not found in this scope
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0425`.

tests/ui/cfg/cfg-false-feature.rs

@@ -1,10 +1,10 @@
-// Features above `cfg(FALSE)` are in effect in a fully unconfigured crate (issue #104633).
+// Features above `cfg(false)` are in effect in a fully unconfigured crate (issue #104633).
 
 //@ check-pass
 //@ compile-flags: --crate-type lib
 
 #![feature(decl_macro)]
-#![cfg(FALSE)]
+#![cfg(false)]
 #![feature(box_patterns)]
 
 macro mac() {} // OK

tests/ui/cfg/cfg-macros-notfoo.rs

@@ -3,7 +3,7 @@
 // check that cfg correctly chooses between the macro impls (see also
 // cfg-macros-foo.rs)
 
-#[cfg(FALSE)]
+#[cfg(false)]
 #[macro_use]
 mod foo {
     macro_rules! bar {

tests/ui/cfg/cfg-match-arm.rs

@@ -11,7 +11,7 @@ fn foo(f: Foo) {
         Foo::Bar => {},
         #[cfg(not(FALSE))]
         Foo::Baz => {},
-        #[cfg(FALSE)]
+        #[cfg(false)]
         Basdfwe => {}
     }
 }

tests/ui/cfg/cfg-stmt-recovery.rs

@@ -6,7 +6,7 @@
 #[cfg_eval]
 fn main() {
     #[cfg_eval]
-    let _ = #[cfg(FALSE)] 0;
+    let _ = #[cfg(false)] 0;
     //~^ ERROR removing an expression is not supported in this position
     //~| ERROR expected expression, found `;`
     //~| ERROR removing an expression is not supported in this position

tests/ui/cfg/cfg-stmt-recovery.stderr

@@ -1,19 +1,19 @@
 error: removing an expression is not supported in this position
   --> $DIR/cfg-stmt-recovery.rs:9:13
    |
-LL |     let _ = #[cfg(FALSE)] 0;
+LL |     let _ = #[cfg(false)] 0;
    |             ^^^^^^^^^^^^^
 
 error: expected expression, found `;`
   --> $DIR/cfg-stmt-recovery.rs:9:28
    |
-LL |     let _ = #[cfg(FALSE)] 0;
+LL |     let _ = #[cfg(false)] 0;
    |                            ^ expected expression
 
 error: removing an expression is not supported in this position
   --> $DIR/cfg-stmt-recovery.rs:9:13
    |
-LL |     let _ = #[cfg(FALSE)] 0;
+LL |     let _ = #[cfg(false)] 0;
    |             ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors

tests/ui/cfg/cfg_stmt_expr.rs

@@ -7,47 +7,47 @@
 
 fn main() {
     let a = 413;
-    #[cfg(FALSE)]
+    #[cfg(false)]
     let a = ();
     assert_eq!(a, 413);
 
     let mut b = 612;
-    #[cfg(FALSE)]
+    #[cfg(false)]
     {
         b = 1111;
     }
     assert_eq!(b, 612);
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     undefined_fn();
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     undefined_macro!();
-    #[cfg(FALSE)]
+    #[cfg(false)]
     undefined_macro![];
-    #[cfg(FALSE)]
+    #[cfg(false)]
     undefined_macro!{};
 
     // pretty printer bug...
-    // #[cfg(FALSE)]
+    // #[cfg(false)]
     // undefined_macro!{}
 
-    let () = (#[cfg(FALSE)] 341,); // Should this also work on parens?
+    let () = (#[cfg(false)] 341,); // Should this also work on parens?
-    let t = (1, #[cfg(FALSE)] 3, 4);
+    let t = (1, #[cfg(false)] 3, 4);
     assert_eq!(t, (1, 4));
 
     let f = |_: u32, _: u32| ();
-    f(2, 1, #[cfg(FALSE)] 6);
+    f(2, 1, #[cfg(false)] 6);
 
-    let _: u32 = a.clone(#[cfg(FALSE)] undefined);
+    let _: u32 = a.clone(#[cfg(false)] undefined);
 
-    let _: [(); 0] = [#[cfg(FALSE)] 126];
+    let _: [(); 0] = [#[cfg(false)] 126];
-    let t = [#[cfg(FALSE)] 1, 2, 6];
+    let t = [#[cfg(false)] 1, 2, 6];
     assert_eq!(t, [2, 6]);
 
     {
         let r;
-        #[cfg(FALSE)]
+        #[cfg(false)]
         (r = 5);
         #[cfg(not(FALSE))]
         (r = 10);
@@ -75,7 +75,7 @@ fn main() {
         612
     });
 
-    assert_eq!((#[cfg(FALSE)] 1, #[cfg(not(FALSE))] 2), (2,));
+    assert_eq!((#[cfg(false)] 1, #[cfg(not(FALSE))] 2), (2,));
     assert_eq!(n, 612);
 
     // check that lints work

tests/ui/cfg/cmdline-false.rs

@@ -0,0 +1,9 @@
+/// Test that `--cfg false` doesn't cause `cfg(false)` to evaluate to `true`
+//@ compile-flags: --cfg false
+
+#[cfg(false)]
+fn foo() {}
+
+fn main() {
+    foo();  //~ ERROR cannot find function `foo` in this scope
+}

tests/ui/cfg/cmdline-false.stderr

@@ -0,0 +1,9 @@
+error[E0425]: cannot find function `foo` in this scope
+  --> $DIR/cmdline-false.rs:8:5
+   |
+LL |     foo();
+   |     ^^^ not found in this scope
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0425`.

tests/ui/cfg/conditional-compile.rs

@@ -6,16 +6,16 @@
 
 // Crate use statements
 
-#[cfg(FALSE)]
+#[cfg(false)]
 use flippity;
 
-#[cfg(FALSE)]
+#[cfg(false)]
 static b: bool = false;
 
 static b: bool = true;
 
 mod rustrt {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     extern "C" {
         // This symbol doesn't exist and would be a link error if this
         // module was codegened
@@ -25,12 +25,12 @@ mod rustrt {
     extern "C" {}
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 type t = isize;
 
 type t = bool;
 
-#[cfg(FALSE)]
+#[cfg(false)]
 enum tg {
     foo,
 }
@@ -39,12 +39,12 @@ enum tg {
     bar,
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 struct r {
     i: isize,
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn r(i: isize) -> r {
     r { i: i }
 }
@@ -57,7 +57,7 @@ fn r(i: isize) -> r {
     r { i: i }
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 mod m {
     // This needs to parse but would fail in typeck. Since it's not in
     // the current config it should not be typechecked.
@@ -69,7 +69,7 @@ mod m {
 mod m {
     // Submodules have slightly different code paths than the top-level
     // module, so let's make sure this jazz works here as well
-    #[cfg(FALSE)]
+    #[cfg(false)]
     pub fn f() {}
 
     pub fn f() {}
@@ -77,7 +77,7 @@ mod m {
 
 // Since the FALSE configuration isn't defined main will just be
 // parsed, but nothing further will be done with it
-#[cfg(FALSE)]
+#[cfg(false)]
 pub fn main() {
     panic!()
 }
@@ -93,14 +93,14 @@ pub fn main() {
 }
 
 fn test_in_fn_ctxt() {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     fn f() {
         panic!()
     }
     fn f() {}
     f();
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     static i: isize = 0;
     static i: isize = 1;
     assert_eq!(i, 1);
@@ -109,7 +109,7 @@ fn test_in_fn_ctxt() {
 mod test_foreign_items {
     pub mod rustrt {
         extern "C" {
-            #[cfg(FALSE)]
+            #[cfg(false)]
             pub fn write() -> String;
             pub fn write() -> String;
         }
@@ -117,7 +117,7 @@ mod test_foreign_items {
 }
 
 mod test_use_statements {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     use flippity_foo;
 }
 
@@ -127,24 +127,24 @@ mod test_methods {
     }
 
     impl Fooable for Foo {
-        #[cfg(FALSE)]
+        #[cfg(false)]
         fn what(&self) {}
 
         fn what(&self) {}
 
-        #[cfg(FALSE)]
+        #[cfg(false)]
         fn the(&self) {}
 
         fn the(&self) {}
     }
 
     trait Fooable {
-        #[cfg(FALSE)]
+        #[cfg(false)]
         fn what(&self);
 
         fn what(&self);
 
-        #[cfg(FALSE)]
+        #[cfg(false)]
         fn the(&self);
 
         fn the(&self);

tests/ui/cfg/diagnostics-cross-crate.stderr

@@ -12,7 +12,7 @@ LL |     pub mod doesnt_exist {
 note: the item is gated here
   --> $DIR/auxiliary/cfged_out.rs:5:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in crate `cfged_out`
@@ -35,7 +35,7 @@ LL |     pub fn uwu() {}
 note: the item is gated here
   --> $DIR/auxiliary/cfged_out.rs:2:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `meow` in module `cfged_out::inner::right`

tests/ui/cfg/diagnostics-reexport.rs

@@ -1,10 +1,10 @@
 pub mod inner {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     mod gone {
         pub fn uwu() {}
     }
 
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     pub use super::uwu;
     //~^ NOTE found an item that was configured out
 }
@@ -14,7 +14,7 @@ pub use a::x;
 //~| NOTE no `x` in `a`
 
 mod a {
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     pub fn x() {}
     //~^ NOTE found an item that was configured out
 }
@@ -25,10 +25,10 @@ pub use b::{x, y};
 //~| NOTE no `y` in `b`
 
 mod b {
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     pub fn x() {}
     //~^ NOTE found an item that was configured out
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     pub fn y() {}
     //~^ NOTE found an item that was configured out
 }

tests/ui/cfg/diagnostics-reexport.stderr

@@ -12,7 +12,7 @@ LL |     pub fn x() {}
 note: the item is gated here
   --> $DIR/diagnostics-reexport.rs:17:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0432]: unresolved imports `b::x`, `b::y`
@@ -31,7 +31,7 @@ LL |     pub fn x() {}
 note: the item is gated here
   --> $DIR/diagnostics-reexport.rs:28:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 note: found an item that was configured out
   --> $DIR/diagnostics-reexport.rs:32:12
@@ -41,7 +41,7 @@ LL |     pub fn y() {}
 note: the item is gated here
   --> $DIR/diagnostics-reexport.rs:31:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
@@ -58,7 +58,7 @@ LL |     pub use super::uwu;
 note: the item is gated here
   --> $DIR/diagnostics-reexport.rs:7:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors

tests/ui/cfg/diagnostics-same-crate.rs

@@ -1,11 +1,11 @@
 #![allow(unexpected_cfgs)] // since we want to recognize them as unexpected
 
 pub mod inner {
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     pub fn uwu() {}
     //~^ NOTE found an item that was configured out
 
-    #[cfg(FALSE)] //~ NOTE the item is gated here
+    #[cfg(false)] //~ NOTE the item is gated here
     //~^ NOTE the item is gated here
     //~| NOTE the item is gated here
     pub mod doesnt_exist {

tests/ui/cfg/diagnostics-same-crate.stderr

@@ -12,7 +12,7 @@ LL |     pub mod doesnt_exist {
 note: the item is gated here
   --> $DIR/diagnostics-same-crate.rs:8:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0432]: unresolved import `super::inner::doesnt_exist`
@@ -29,7 +29,7 @@ LL |     pub mod doesnt_exist {
 note: the item is gated here
   --> $DIR/diagnostics-same-crate.rs:8:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
@@ -46,7 +46,7 @@ LL |     pub mod doesnt_exist {
 note: the item is gated here
   --> $DIR/diagnostics-same-crate.rs:8:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
@@ -63,7 +63,7 @@ LL |     pub fn uwu() {}
 note: the item is gated here
   --> $DIR/diagnostics-same-crate.rs:4:5
    |
-LL |     #[cfg(FALSE)]
+LL |     #[cfg(false)]
    |     ^^^^^^^^^^^^^
 
 error[E0425]: cannot find function `meow` in module `inner::right`

tests/ui/cfg/true-false.rs

@@ -1,7 +1,6 @@
 //@ run-pass
 
 #![feature(link_cfg)]
-#![feature(cfg_boolean_literals)]
 
 #[cfg(true)]
 fn foo() -> bool {

tests/ui/check-cfg/allow-same-level.rs

@@ -12,7 +12,7 @@
 //@ compile-flags: --check-cfg=cfg() --cfg=unknown_but_active_cfg
 
 #[allow(unexpected_cfgs)]
-#[cfg(FALSE)]
+#[cfg(unknown_and_inactive_cfg)]
 //~^ WARNING unexpected `cfg` condition name
 fn bar() {}
 

tests/ui/check-cfg/allow-same-level.stderr

@@ -1,10 +1,10 @@
-warning: unexpected `cfg` condition name: `FALSE`
+warning: unexpected `cfg` condition name: `unknown_and_inactive_cfg`
   --> $DIR/allow-same-level.rs:15:7
    |
-LL | #[cfg(FALSE)]
+LL | #[cfg(unknown_and_inactive_cfg)]
-   |       ^^^^^
+   |       ^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: to expect this configuration use `--check-cfg=cfg(FALSE)`
+   = help: to expect this configuration use `--check-cfg=cfg(unknown_and_inactive_cfg)`
    = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
    = note: `#[warn(unexpected_cfgs)]` on by default
 

tests/ui/check-cfg/allow-top-level.rs

@@ -6,7 +6,7 @@
 
 #![allow(unexpected_cfgs)]
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn bar() {}
 
 fn foo() {

tests/ui/check-cfg/allow-upper-level.rs

@@ -6,7 +6,7 @@
 
 #[allow(unexpected_cfgs)]
 mod aa {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     fn bar() {}
 }
 

tests/ui/conditional-compilation/cfg-generic-params.rs

@@ -1,18 +1,18 @@
 //@ compile-flags:--cfg yes --check-cfg=cfg(yes,no)
 
-fn f_lt<#[cfg(yes)] 'a: 'a, #[cfg(FALSE)] T>() {}
+fn f_lt<#[cfg(yes)] 'a: 'a, #[cfg(false)] T>() {}
-fn f_ty<#[cfg(FALSE)] 'a: 'a, #[cfg(yes)] T>() {}
+fn f_ty<#[cfg(false)] 'a: 'a, #[cfg(yes)] T>() {}
 
-type FnGood = for<#[cfg(yes)] 'a, #[cfg(FALSE)] T> fn(); // OK
+type FnGood = for<#[cfg(yes)] 'a, #[cfg(false)] T> fn(); // OK
-type FnBad = for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> fn();
+type FnBad = for<#[cfg(false)] 'a, #[cfg(yes)] T> fn();
 //~^ ERROR only lifetime parameters can be used in this context
 
-type PolyGood = dyn for<#[cfg(yes)] 'a, #[cfg(FALSE)] T> Copy; // OK
+type PolyGood = dyn for<#[cfg(yes)] 'a, #[cfg(false)] T> Copy; // OK
-type PolyBad = dyn for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> Copy;
+type PolyBad = dyn for<#[cfg(false)] 'a, #[cfg(yes)] T> Copy;
 //~^ ERROR only lifetime parameters can be used in this context
 
-struct WhereGood where for<#[cfg(yes)] 'a, #[cfg(FALSE)] T> u8: Copy; // OK
+struct WhereGood where for<#[cfg(yes)] 'a, #[cfg(false)] T> u8: Copy; // OK
-struct WhereBad where for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> u8: Copy;
+struct WhereBad where for<#[cfg(false)] 'a, #[cfg(yes)] T> u8: Copy;
 //~^ ERROR only lifetime parameters can be used in this context
 
 fn f_lt_no<#[cfg_attr(FALSE, unknown)] 'a>() {} // OK

tests/ui/conditional-compilation/cfg-generic-params.stderr

@@ -31,7 +31,7 @@ LL | struct WhereYes where for<#[cfg_attr(yes, unknown)] 'a> u8: Copy;
 error[E0658]: only lifetime parameters can be used in this context
   --> $DIR/cfg-generic-params.rs:7:48
    |
-LL | type FnBad = for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> fn();
+LL | type FnBad = for<#[cfg(false)] 'a, #[cfg(yes)] T> fn();
    |                                                ^
    |
    = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
@@ -41,7 +41,7 @@ LL | type FnBad = for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> fn();
 error[E0658]: only lifetime parameters can be used in this context
   --> $DIR/cfg-generic-params.rs:11:54
    |
-LL | type PolyBad = dyn for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> Copy;
+LL | type PolyBad = dyn for<#[cfg(false)] 'a, #[cfg(yes)] T> Copy;
    |                                                      ^
    |
    = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
@@ -51,7 +51,7 @@ LL | type PolyBad = dyn for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> Copy;
 error[E0658]: only lifetime parameters can be used in this context
   --> $DIR/cfg-generic-params.rs:15:57
    |
-LL | struct WhereBad where for<#[cfg(FALSE)] 'a, #[cfg(yes)] T> u8: Copy;
+LL | struct WhereBad where for<#[cfg(false)] 'a, #[cfg(yes)] T> u8: Copy;
    |                                                         ^
    |
    = note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information

tests/ui/conditional-compilation/cfg-in-crate-1.rs

@@ -1 +1 @@
-#![cfg(FALSE)] //~ ERROR `main` function not found in crate `cfg_in_crate_1`
+#![cfg(false)] //~ ERROR `main` function not found in crate `cfg_in_crate_1`

tests/ui/conditional-compilation/cfg-in-crate-1.stderr

@@ -1,7 +1,7 @@
 error[E0601]: `main` function not found in crate `cfg_in_crate_1`
   --> $DIR/cfg-in-crate-1.rs:1:15
    |
-LL | #![cfg(FALSE)]
+LL | #![cfg(false)]
    |               ^ consider adding a `main` function to `$DIR/cfg-in-crate-1.rs`
 
 error: aborting due to 1 previous error

tests/ui/conditional-compilation/cfg-non-opt-expr.rs

@@ -2,10 +2,10 @@
 #![feature(custom_test_frameworks)]
 
 fn main() {
-    let _ = #[cfg(FALSE)] ();
+    let _ = #[cfg(false)] ();
     //~^ ERROR removing an expression is not supported in this position
-    let _ = 1 + 2 + #[cfg(FALSE)] 3;
+    let _ = 1 + 2 + #[cfg(false)] 3;
     //~^ ERROR removing an expression is not supported in this position
-    let _ = [1, 2, 3][#[cfg(FALSE)] 1];
+    let _ = [1, 2, 3][#[cfg(false)] 1];
     //~^ ERROR removing an expression is not supported in this position
 }

tests/ui/conditional-compilation/cfg-non-opt-expr.stderr

@@ -1,19 +1,19 @@
 error: removing an expression is not supported in this position
   --> $DIR/cfg-non-opt-expr.rs:5:13
    |
-LL |     let _ = #[cfg(FALSE)] ();
+LL |     let _ = #[cfg(false)] ();
    |             ^^^^^^^^^^^^^
 
 error: removing an expression is not supported in this position
   --> $DIR/cfg-non-opt-expr.rs:7:21
    |
-LL |     let _ = 1 + 2 + #[cfg(FALSE)] 3;
+LL |     let _ = 1 + 2 + #[cfg(false)] 3;
    |                     ^^^^^^^^^^^^^
 
 error: removing an expression is not supported in this position
   --> $DIR/cfg-non-opt-expr.rs:9:23
    |
-LL |     let _ = [1, 2, 3][#[cfg(FALSE)] 1];
+LL |     let _ = [1, 2, 3][#[cfg(false)] 1];
    |                       ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors

tests/ui/conditional-compilation/module_with_cfg.rs

@@ -1,3 +1,3 @@
 //@ ignore-test (auxiliary, used by other tests)
 
-#![cfg_attr(all(), cfg(FALSE))]
+#![cfg_attr(all(), cfg(false))]

tests/ui/consts/const-extern-fn/issue-68062-const-extern-fns-dont-need-fn-specifier-2.rs

@@ -1,6 +1,6 @@
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn container() {
     const unsafe WhereIsFerris Now() {}
     //~^ ERROR expected one of `extern` or `fn`

tests/ui/consts/const-extern-fn/issue-68062-const-extern-fns-dont-need-fn-specifier.rs

@@ -1,6 +1,6 @@
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn container() {
     const extern "Rust" PUT_ANYTHING_YOU_WANT_HERE bug() -> usize { 1 }
     //~^ ERROR expected `fn`

tests/ui/delegation/explicit-paths-signature-pass.rs

@@ -6,7 +6,7 @@
 mod to_reuse {
     use crate::S;
 
-    pub fn foo<'a>(#[cfg(FALSE)] a: u8, _b: &'a S) -> u32 {
+    pub fn foo<'a>(#[cfg(false)] a: u8, _b: &'a S) -> u32 {
         1
     }
 }

tests/ui/expr/if/attrs/bad-cfg.rs

@@ -1,5 +1,5 @@
 #![feature(stmt_expr_attributes)]
 
 fn main() {
-    let _ = #[cfg(FALSE)] if true {}; //~ ERROR removing an expression
+    let _ = #[cfg(false)] if true {}; //~ ERROR removing an expression
 }

tests/ui/expr/if/attrs/bad-cfg.stderr

@@ -1,7 +1,7 @@
 error: removing an expression is not supported in this position
   --> $DIR/bad-cfg.rs:4:13
    |
-LL |     let _ = #[cfg(FALSE)] if true {};
+LL |     let _ = #[cfg(false)] if true {};
    |             ^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error

tests/ui/expr/if/attrs/cfg-false-if-attr.rs

@@ -1,12 +1,12 @@
 //@ check-pass
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn simple_attr() {
     #[attr] if true {}
     #[allow_warnings] if true {}
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn if_else_chain() {
     #[first_attr] if true {
     } else if false {
@@ -14,20 +14,20 @@ fn if_else_chain() {
     }
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn if_let() {
     #[attr] if let Some(_) = Some(true) {}
 }
 
 fn bar() {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     if true {
-        let x: () = true; // Should not error due to the #[cfg(FALSE)]
+        let x: () = true; // Should not error due to the #[cfg(false)]
     }
 
-    #[cfg_attr(not(FALSE), cfg(FALSE))]
+    #[cfg_attr(not(FALSE), cfg(false))]
     if true {
-        let a: () = true; // Should not error due to the applied #[cfg(FALSE)]
+        let a: () = true; // Should not error due to the applied #[cfg(false)]
     }
 }
 

tests/ui/expr/if/attrs/else-attrs.rs

@@ -1,11 +1,11 @@
-#[cfg(FALSE)]
+#[cfg(false)]
 fn if_else_parse_error() {
     if true {
     } #[attr] else if false { //~ ERROR expected
     }
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn else_attr_ifparse_error() {
     if true {
     } else #[attr] if false { //~ ERROR outer attributes are not allowed
@@ -13,7 +13,7 @@ fn else_attr_ifparse_error() {
     }
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn else_parse_error() {
     if true {
     } else if false {

tests/ui/expr/if/attrs/gate-whole-expr.rs

@@ -3,7 +3,7 @@
 fn main() {
     let x = 1;
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     if false {
         x = 2;
     } else if true {

tests/ui/expr/if/attrs/let-chains-attr.rs

@@ -2,7 +2,7 @@
 
 #![feature(let_chains)]
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn foo() {
     #[attr]
     if let Some(_) = Some(true) && let Ok(_) = Ok(1) {

tests/ui/feature-gates/feature-gate-cfg-boolean-literals.rs

@@ -1,10 +0,0 @@
-#[cfg(true)] //~ ERROR `cfg(true)` is experimental
-fn foo() {}
-
-#[cfg_attr(true, cfg(false))] //~ ERROR `cfg(true)` is experimental
-//~^ ERROR `cfg(false)` is experimental
-fn foo() {}
-
-fn main() {
-    cfg!(false); //~ ERROR `cfg(false)` is experimental
-}

tests/ui/feature-gates/feature-gate-cfg-boolean-literals.stderr

@@ -1,43 +0,0 @@
-error[E0658]: `cfg(true)` is experimental and subject to change
-  --> $DIR/feature-gate-cfg-boolean-literals.rs:1:7
-   |
-LL | #[cfg(true)]
-   |       ^^^^
-   |
-   = note: see issue #131204 <https://github.com/rust-lang/rust/issues/131204> for more information
-   = help: add `#![feature(cfg_boolean_literals)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: `cfg(true)` is experimental and subject to change
-  --> $DIR/feature-gate-cfg-boolean-literals.rs:4:12
-   |
-LL | #[cfg_attr(true, cfg(false))]
-   |            ^^^^
-   |
-   = note: see issue #131204 <https://github.com/rust-lang/rust/issues/131204> for more information
-   = help: add `#![feature(cfg_boolean_literals)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: `cfg(false)` is experimental and subject to change
-  --> $DIR/feature-gate-cfg-boolean-literals.rs:4:22
-   |
-LL | #[cfg_attr(true, cfg(false))]
-   |                      ^^^^^
-   |
-   = note: see issue #131204 <https://github.com/rust-lang/rust/issues/131204> for more information
-   = help: add `#![feature(cfg_boolean_literals)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error[E0658]: `cfg(false)` is experimental and subject to change
-  --> $DIR/feature-gate-cfg-boolean-literals.rs:9:10
-   |
-LL |     cfg!(false);
-   |          ^^^^^
-   |
-   = note: see issue #131204 <https://github.com/rust-lang/rust/issues/131204> for more information
-   = help: add `#![feature(cfg_boolean_literals)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-
-error: aborting due to 4 previous errors
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/feature-gates/feature-gate-coroutines.rs

@@ -12,7 +12,7 @@ fn main() {
     //~^^ ERROR `yield` can only be used
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn foo() {
     // Ok in 2024 edition
     yield; //~ ERROR yield syntax is experimental

tests/ui/feature-gates/feature-gate-deref_patterns.rs

@@ -4,6 +4,6 @@ fn main() {
     println!("x: {}", x);
 
     // `box` syntax is allowed to be cfg-ed out for historical reasons (#65742).
-    #[cfg(FALSE)]
+    #[cfg(false)]
     let box _x = Box::new('c');
 }

tests/ui/feature-gates/feature-gate-gen_blocks.rs

@@ -17,7 +17,7 @@ fn test_async_gen() {
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn foo() {
     gen {};
     //[e2024]~^ ERROR: gen blocks are experimental

tests/ui/feature-gates/feature-gate-guard-patterns.rs

@@ -30,7 +30,7 @@ fn other_guards_dont() {
     while let (x if guard(x)) = 0 {}
     //~^ ERROR: guard patterns are experimental
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     while let (x if guard(x)) = 0 {}
     //~^ ERROR: guard patterns are experimental
 }

tests/ui/feature-gates/feature-gate-mut-ref.rs

@@ -6,8 +6,8 @@ fn main() {
     let mut ref mut z = 14; //~  ERROR [E0658]
     z = &mut 15;
 
-    #[cfg(FALSE)]
+    #[cfg(false)]
     let mut ref x = 10; //~  ERROR [E0658]
-    #[cfg(FALSE)]
+    #[cfg(false)]
     let mut ref mut y = 10; //~  ERROR [E0658]
 }

tests/ui/feature-gates/feature-gate-never_patterns.rs

@@ -15,12 +15,12 @@ fn main() {
             //~^ ERROR `!` patterns are experimental
         }
         // Check that the gate operates even behind `cfg`.
-        #[cfg(FALSE)]
+        #[cfg(false)]
         match *ptr {
             !
             //~^ ERROR `!` patterns are experimental
         }
-        #[cfg(FALSE)]
+        #[cfg(false)]
         match *ptr {
             ! => {}
             //~^ ERROR `!` patterns are experimental
@@ -60,13 +60,13 @@ fn main() {
     // Check that the gate operates even behind `cfg`.
     match Some(0) {
         None => {}
-        #[cfg(FALSE)]
+        #[cfg(false)]
         Some(_)
         //~^ ERROR `match` arm with no body
     }
     match Some(0) {
         _ => {}
-        #[cfg(FALSE)]
+        #[cfg(false)]
         Some(_) if false
         //~^ ERROR `match` arm with no body
     }

tests/ui/feature-gates/feature-gate-postfix_match.rs

@@ -9,7 +9,7 @@ fn main() {
     };
 
     // Test that the gate works behind a cfg
-    #[cfg(FALSE)]
+    #[cfg(false)]
     val.match { //~ ERROR postfix match is experimental
         Some(42) => "the answer to life, the universe, and everything",
         _ => "might be the answer to something"

tests/ui/feature-gates/feature-gate-yeet_expr-in-cfg.rs

@@ -1,7 +1,7 @@
 //@ edition: 2021
 
 pub fn demo() -> Option<i32> {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     {
         do yeet //~ ERROR `do yeet` expression is experimental
     }
@@ -9,7 +9,7 @@ pub fn demo() -> Option<i32> {
     Some(1)
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 pub fn alternative() -> Result<(), String> {
     do yeet "hello"; //~ ERROR `do yeet` expression is experimental
 }

tests/ui/feature-gates/soft-syntax-gates-with-errors.rs

@@ -5,7 +5,7 @@
 macro a() {}
 //~^ ERROR: `macro` is experimental
 
-#[cfg(FALSE)]
+#[cfg(false)]
 macro b() {}
 
 macro_rules! identity {
@@ -17,13 +17,13 @@ identity! {
     //~^ ERROR: `macro` is experimental
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 identity! {
     macro d() {} // No error
 }
 
 identity! {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     macro e() {}
 }
 

tests/ui/feature-gates/soft-syntax-gates-without-errors.rs

@@ -2,7 +2,7 @@
 // This file is used to test the behavior of the early-pass syntax warnings.
 // If macro syntax is stabilized, replace with a different unstable syntax.
 
-#[cfg(FALSE)]
+#[cfg(false)]
 macro b() {}
 //~^ WARN: `macro` is experimental
 //~| WARN: unstable syntax
@@ -11,13 +11,13 @@ macro_rules! identity {
     ($($x:tt)*) => ($($x)*);
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 identity! {
     macro d() {} // No error
 }
 
 identity! {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     macro e() {}
     //~^ WARN: `macro` is experimental
     //~| WARN: unstable syntax

tests/ui/feature-gates/stmt_expr_attrs_no_feature.rs

@@ -25,7 +25,7 @@ fn main() {
 
 // Check that cfg works right
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn c() {
     #[rustc_dummy]
     5;
@@ -37,7 +37,7 @@ fn j() {
     5;
 }
 
-#[cfg_attr(not(FALSE), cfg(FALSE))]
+#[cfg_attr(not(FALSE), cfg(false))]
 fn d() {
     #[rustc_dummy]
     8;
@@ -57,7 +57,7 @@ macro_rules! item_mac {
             #[rustc_dummy]
             42;
 
-            #[cfg(FALSE)]
+            #[cfg(false)]
             fn f() {
                 #[rustc_dummy]
                 5;
@@ -69,7 +69,7 @@ macro_rules! item_mac {
                 5;
             }
 
-            #[cfg_attr(not(FALSE), cfg(FALSE))]
+            #[cfg_attr(not(FALSE), cfg(false))]
             fn g() {
                 #[rustc_dummy]
                 8;
@@ -90,42 +90,42 @@ item_mac!(e);
 // check that the gate visitor works right:
 
 extern "C" {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     fn x(a: [u8; #[rustc_dummy] 5]);
     fn y(a: [u8; #[rustc_dummy] 5]); //~ ERROR attributes on expressions are experimental
 }
 
 struct Foo;
 impl Foo {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     const X: u8 = #[rustc_dummy] 5;
     const Y: u8 = #[rustc_dummy] 5; //~ ERROR attributes on expressions are experimental
 }
 
 trait Bar {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     const X: [u8; #[rustc_dummy] 5];
     const Y: [u8; #[rustc_dummy] 5]; //~ ERROR attributes on expressions are experimental
 }
 
 struct Joyce {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     field: [u8; #[rustc_dummy] 5],
     field2: [u8; #[rustc_dummy] 5] //~ ERROR attributes on expressions are experimental
 }
 
 struct Walky(
-    #[cfg(FALSE)] [u8; #[rustc_dummy] 5],
+    #[cfg(false)] [u8; #[rustc_dummy] 5],
     [u8; #[rustc_dummy] 5] //~ ERROR attributes on expressions are experimental
 );
 
 enum Mike {
     Happy(
-        #[cfg(FALSE)] [u8; #[rustc_dummy] 5],
+        #[cfg(false)] [u8; #[rustc_dummy] 5],
         [u8; #[rustc_dummy] 5] //~ ERROR attributes on expressions are experimental
     ),
     Angry {
-        #[cfg(FALSE)]
+        #[cfg(false)]
         field: [u8; #[rustc_dummy] 5],
         field2: [u8; #[rustc_dummy] 5] //~ ERROR attributes on expressions are experimental
     }
@@ -133,7 +133,7 @@ enum Mike {
 
 fn pat() {
     match 5 {
-        #[cfg(FALSE)]
+        #[cfg(false)]
         5 => #[rustc_dummy] (),
         6 => #[rustc_dummy] (), //~ ERROR attributes on expressions are experimental
         _ => (),

tests/ui/filter-block-view-items.rs

@@ -3,5 +3,5 @@
 pub fn main() {
     // Make sure that this view item is filtered out because otherwise it would
     // trigger a compilation error
-    #[cfg(FALSE)] use bar as foo;
+    #[cfg(false)] use bar as foo;
 }

tests/ui/half-open-range-patterns/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs

@@ -9,7 +9,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn syntax() {
     match scrutinee {
         ...X => {} //~ ERROR range-to patterns with `...` are not allowed

tests/ui/half-open-range-patterns/half-open-range-pats-inclusive-no-end.rs

@@ -3,7 +3,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn foo() {
     if let 0... = 1 {} //~ ERROR inclusive range with no end
     if let 0..= = 1 {} //~ ERROR inclusive range with no end

tests/ui/half-open-range-patterns/half-open-range-pats-ref-ambiguous-interp.rs

@@ -1,6 +1,6 @@
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn syntax() {
     match &0 {
         &0.. | _ => {}

tests/ui/half-open-range-patterns/half-open-range-pats-syntactic-pass.rs

@@ -4,7 +4,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn syntax() {
     match scrutinee {
         X.. | 0.. | 'a'.. | 0.0f32.. => {}

tests/ui/inner-attrs-on-impl.rs

@@ -3,7 +3,7 @@
 struct Foo;
 
 impl Foo {
-    #![cfg(FALSE)]
+    #![cfg(false)]
 
     fn method(&self) -> bool { false }
 }
@@ -12,7 +12,7 @@ impl Foo {
     #![cfg(not(FALSE))]
 
     // check that we don't eat attributes too eagerly.
-    #[cfg(FALSE)]
+    #[cfg(false)]
     fn method(&self) -> bool { false }
 
     fn method(&self) -> bool { true }

tests/ui/issues/issue-11004.rs

@@ -9,7 +9,7 @@ unsafe fn access(n:*mut A) -> (i32, f64) {
     (x, y)
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 unsafe fn access(n:*mut A) -> (i32, f64) {
     let x : i32 = (*n).x;
     let y : f64 = (*n).y;

tests/ui/issues/issue-11085.rs

@@ -3,7 +3,7 @@
 #![allow(dead_code)]
 
 struct Foo {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     bar: baz,
     foo: isize,
 }
@@ -15,18 +15,18 @@ struct Foo2 {
 
 enum Bar1 {
     Bar1_1,
-    #[cfg(FALSE)]
+    #[cfg(false)]
     Bar1_2(NotAType),
 }
 
 enum Bar2 {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     Bar2_1(NotAType),
 }
 
 enum Bar3 {
     Bar3_1 {
-        #[cfg(FALSE)]
+        #[cfg(false)]
         foo: isize,
         bar: isize,
     }

tests/ui/issues/issue-16819.rs

@@ -3,7 +3,7 @@
 // `#[cfg]` on struct field permits empty unusable struct
 
 struct S {
-    #[cfg(FALSE)]
+    #[cfg(false)]
     a: int,
 }
 

tests/ui/lexer/error-stage.rs

@@ -59,7 +59,7 @@ const _: () = sink! {
 
 // The invalid literals used to cause errors, but this was changed by #102944.
 // Except for `0b010.0f32`, because it's a lexer error.
-#[cfg(FALSE)]
+#[cfg(false)]
 fn configured_out() {
     "string"any_suffix; // OK
     10u123; // OK

tests/ui/link-native-libs/link-attr-validation-late.rs

@@ -9,7 +9,7 @@ extern "C" {}
 #[link(name = "foo", name = "bar")] //~ ERROR multiple `name` arguments
 #[link(name = "...", kind = "dylib", kind = "bar")] //~ ERROR multiple `kind` arguments
 #[link(name = "...", modifiers = "+verbatim", modifiers = "bar")] //~ ERROR multiple `modifiers` arguments
-#[link(name = "...", cfg(FALSE), cfg(FALSE))] //~ ERROR multiple `cfg` arguments
+#[link(name = "...", cfg(false), cfg(false))] //~ ERROR multiple `cfg` arguments
 #[link(wasm_import_module = "foo", wasm_import_module = "bar")] //~ ERROR multiple `wasm_import_module` arguments
 extern "C" {}
 

tests/ui/link-native-libs/link-attr-validation-late.stderr

@@ -31,7 +31,7 @@ LL | #[link(name = "...", modifiers = "+verbatim", modifiers = "bar")]
 error: multiple `cfg` arguments in a single `#[link]` attribute
   --> $DIR/link-attr-validation-late.rs:12:34
    |
-LL | #[link(name = "...", cfg(FALSE), cfg(FALSE))]
+LL | #[link(name = "...", cfg(false), cfg(false))]
    |                                  ^^^^^^^^^^
 
 error: multiple `wasm_import_module` arguments in a single `#[link]` attribute

tests/ui/lint/inert-attr-macro.rs

@@ -1,6 +1,5 @@
 //@ check-pass
 
-#![feature(cfg_boolean_literals)]
 #![warn(unused)]
 
 macro_rules! foo {

tests/ui/lint/inert-attr-macro.stderr

@@ -1,41 +1,41 @@
 warning: unused attribute `inline`
-  --> $DIR/inert-attr-macro.rs:11:5
+  --> $DIR/inert-attr-macro.rs:10:5
    |
 LL |     #[inline] foo!();
    |     ^^^^^^^^^
    |
 note: the built-in attribute `inline` will be ignored, since it's applied to the macro invocation `foo`
-  --> $DIR/inert-attr-macro.rs:11:15
+  --> $DIR/inert-attr-macro.rs:10:15
    |
 LL |     #[inline] foo!();
    |               ^^^
 note: the lint level is defined here
-  --> $DIR/inert-attr-macro.rs:4:9
+  --> $DIR/inert-attr-macro.rs:3:9
    |
 LL | #![warn(unused)]
    |         ^^^^^^
    = note: `#[warn(unused_attributes)]` implied by `#[warn(unused)]`
 
 warning: unused attribute `allow`
-  --> $DIR/inert-attr-macro.rs:15:5
+  --> $DIR/inert-attr-macro.rs:14:5
    |
 LL |     #[allow(warnings)] #[inline] foo!();
    |     ^^^^^^^^^^^^^^^^^^
    |
 note: the built-in attribute `allow` will be ignored, since it's applied to the macro invocation `foo`
-  --> $DIR/inert-attr-macro.rs:15:34
+  --> $DIR/inert-attr-macro.rs:14:34
    |
 LL |     #[allow(warnings)] #[inline] foo!();
    |                                  ^^^
 
 warning: unused attribute `inline`
-  --> $DIR/inert-attr-macro.rs:15:24
+  --> $DIR/inert-attr-macro.rs:14:24
    |
 LL |     #[allow(warnings)] #[inline] foo!();
    |                        ^^^^^^^^^
    |
 note: the built-in attribute `inline` will be ignored, since it's applied to the macro invocation `foo`
-  --> $DIR/inert-attr-macro.rs:15:34
+  --> $DIR/inert-attr-macro.rs:14:34
    |
 LL |     #[allow(warnings)] #[inline] foo!();
    |                                  ^^^

tests/ui/lint/unused/unused-attr-macro-rules.rs

@@ -17,7 +17,7 @@ macro_rules! foo2 {
     () => {};
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 macro_rules! foo {
     () => {};
 }

tests/ui/macros/lint-trailing-macro-call.rs

@@ -6,7 +6,7 @@
 
 macro_rules! expand_it {
     () => {
-        #[cfg(FALSE)] 25; //~  WARN trailing semicolon in macro
+        #[cfg(false)] 25; //~  WARN trailing semicolon in macro
                           //~| WARN this was previously
     }
 }

tests/ui/macros/lint-trailing-macro-call.stderr

@@ -1,7 +1,7 @@
 warning: trailing semicolon in macro used in expression position
   --> $DIR/lint-trailing-macro-call.rs:9:25
    |
-LL |         #[cfg(FALSE)] 25;
+LL |         #[cfg(false)] 25;
    |                         ^
 ...
 LL |     expand_it!()
@@ -20,7 +20,7 @@ Future incompatibility report: Future breakage diagnostic:
 warning: trailing semicolon in macro used in expression position
   --> $DIR/lint-trailing-macro-call.rs:9:25
    |
-LL |         #[cfg(FALSE)] 25;
+LL |         #[cfg(false)] 25;
    |                         ^
 ...
 LL |     expand_it!()

tests/ui/macros/macro-attributes.rs

@@ -9,7 +9,7 @@ macro_rules! compiles_fine {
 
         // check that the attributes are recognised by requiring this
         // to be removed to avoid a compile error
-        #[cfg(FALSE)]
+        #[cfg(false)]
         static MISTYPED: () = "foo";
     }
 }

tests/ui/macros/macro-inner-attributes.rs

@@ -5,7 +5,7 @@ macro_rules! test { ($nm:ident,
                      $i:item) => (mod $nm { #![$a] $i }); }
 
 test!(a,
-      #[cfg(FALSE)],
+      #[cfg(false)],
       pub fn bar() { });
 
 test!(b,

tests/ui/macros/macro-outer-attributes.rs

@@ -5,7 +5,7 @@ macro_rules! test { ($nm:ident,
                      $i:item) => (mod $nm { #[$a] $i }); }
 
 test!(a,
-      #[cfg(FALSE)],
+      #[cfg(false)],
       pub fn bar() { });
 
 test!(b,

tests/ui/macros/macro-outer-attributes.stderr

@@ -16,7 +16,7 @@ LL |                        $i:item) => (mod $nm { #[$a] $i }); }
    |                                               ^^^^^
 LL |
 LL | / test!(a,
-LL | |       #[cfg(FALSE)],
+LL | |       #[cfg(false)],
 LL | |       pub fn bar() { });
    | |_______________________- in this macro invocation
    = note: this error originates in the macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

tests/ui/macros/macro-with-attrs2.rs

@@ -1,6 +1,6 @@
 //@ run-pass
 
-#[cfg(FALSE)]
+#[cfg(false)]
 macro_rules! foo { () => (1) }
 
 #[cfg(not(FALSE))]

tests/ui/nested-cfg-attrs.rs

@@ -1,4 +1,4 @@
-#[cfg_attr(all(), cfg_attr(all(), cfg(FALSE)))]
+#[cfg_attr(all(), cfg_attr(all(), cfg(false)))]
 fn f() {}
 
 fn main() { f() } //~ ERROR cannot find function `f` in this scope

tests/ui/or-patterns/fn-param-wrap-parens.fixed

@@ -9,5 +9,5 @@ fn main() {}
 enum E { A, B }
 use E::*;
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn fun1((A | B): E) {} //~ ERROR top-level or-patterns are not allowed

tests/ui/or-patterns/fn-param-wrap-parens.rs

@@ -9,5 +9,5 @@ fn main() {}
 enum E { A, B }
 use E::*;
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn fun1(A | B: E) {} //~ ERROR top-level or-patterns are not allowed

tests/ui/or-patterns/or-patterns-syntactic-pass.rs

@@ -18,7 +18,7 @@ accept_pat!([p | q]);
 
 // Non-macro tests:
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn or_patterns() {
     // Top level of `let`:
     let (| A | B);

tests/ui/or-patterns/remove-leading-vert.fixed

@@ -6,7 +6,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn leading() {
     fn fun1(  A: E) {} //~ ERROR top-level or-patterns are not allowed
     fn fun2(  A: E) {} //~ ERROR unexpected `||` before function parameter
@@ -21,7 +21,7 @@ fn leading() {
     let NS { f: | A }: NS; //~ ERROR unexpected token `||` in pattern
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn trailing() {
     let ( A  ): E; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let (a ,): (E,); //~ ERROR a trailing `|` is not allowed in an or-pattern

tests/ui/or-patterns/remove-leading-vert.rs

@@ -6,7 +6,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn leading() {
     fn fun1( | A: E) {} //~ ERROR top-level or-patterns are not allowed
     fn fun2( || A: E) {} //~ ERROR unexpected `||` before function parameter
@@ -21,7 +21,7 @@ fn leading() {
     let NS { f: || A }: NS; //~ ERROR unexpected token `||` in pattern
 }
 
-#[cfg(FALSE)]
+#[cfg(false)]
 fn trailing() {
     let ( A | ): E; //~ ERROR a trailing `|` is not allowed in an or-pattern
     let (a |,): (E,); //~ ERROR a trailing `|` is not allowed in an or-pattern

tests/ui/parser/assoc/assoc-const-underscore-syntactic-pass.rs

@@ -4,7 +4,7 @@
 
 fn main() {}
 
-#[cfg(FALSE)]
+#[cfg(false)]
 const _: () = {
     pub trait A {
         const _: () = ();