check-cfg seems to be broken for now because this line was removed: https://github.com/rust-lang/rust/pull/140894/files#diff-384affc1b4190940f114f3fcebbf969e7e18657a71ef9001da6b223a036687d9R213

Author: GuillaumeGomez

tests/rustdoc-ui/doc-cfg-check-cfg.cfg_empty.stderr

@@ -11,7 +11,7 @@
 #![feature(doc_cfg)]
 
 #[doc(cfg(foo))]
-//[cfg_empty]~^ WARN unexpected `cfg` condition name: `foo`
+// FIXME: Should emit: WARN unexpected `cfg` condition name: `foo`
 pub fn foo() {}
 
 pub mod module {

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

@@ -4,8 +4,8 @@
 //~^ ERROR
 //~^^ ERROR
 #[doc(cfg(foo), cfg(bar))]
-//~^ WARN unexpected `cfg` condition name: `foo`
-//~^^ WARN unexpected `cfg` condition name: `bar`
+// FIXME: Should emit: WARN unexpected `cfg` condition name: `foo`
+// FIXME: Should emit: WARN unexpected `cfg` condition name: `bar`
 #[doc(cfg())] //~ ERROR
 #[doc(cfg(foo, bar))] //~ ERROR
 pub fn foo() {}

tests/rustdoc-ui/doc-cfg.rs

@@ -10,26 +10,6 @@ error: multiple `cfg` predicates are specified
 LL | #[doc(cfg(), cfg(foo, bar))]
    |                       ^^^
 
-warning: unexpected `cfg` condition name: `foo`
-  --> $DIR/doc-cfg.rs:6:11
-   |
-LL | #[doc(cfg(foo), cfg(bar))]
-   |           ^^^
-   |
-   = help: expected names are: `FALSE` and `test` and 31 more
-   = help: to expect this configuration use `--check-cfg=cfg(foo)`
-   = 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
-
-warning: unexpected `cfg` condition name: `bar`
-  --> $DIR/doc-cfg.rs:6:21
-   |
-LL | #[doc(cfg(foo), cfg(bar))]
-   |                     ^^^
-   |
-   = help: to expect this configuration use `--check-cfg=cfg(bar)`
-   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg.html> for more information about checking conditional configuration
-
 error: `cfg` predicate is not specified
   --> $DIR/doc-cfg.rs:9:7
    |
@@ -42,5 +22,5 @@ error: multiple `cfg` predicates are specified
 LL | #[doc(cfg(foo, bar))]
    |                ^^^
 
-error: aborting due to 4 previous errors; 2 warnings emitted
+error: aborting due to 4 previous errors