Auto merge of #139949 - matthiaskrgr:rollup-pxc5tsx, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #138632 (Stabilize `cfg_boolean_literals`)
 - #139416 (unstable book; document `macro_metavar_expr_concat`)
 - #139782 (Consistent with treating Ctor Call as Struct in liveness analysis)
 - #139885 (document RUSTC_BOOTSTRAP, RUSTC_OVERRIDE_VERSION_STRING, and -Z allow-features in the unstable book)
 - #139904 (Explicitly annotate edition for `unpretty=expanded` and `unpretty=hir` tests)
 - #139932 (transmutability: Refactor tests for simplicity)
 - #139944 (Move eager translation to a method on Diag)
 - #139948 (git: ignore `60600a6fa4` for blame purposes)

r? `@ghost`
`@rustbot` modify labels: rollup

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;
         }
         _ => {