MCP636: Add simpler and more explicit syntax to check-cfg

This add a new form and deprecated the other ones:
 - cfg(name1, ..., nameN, values("value1", "value2", ... "valueN"))
 - cfg(name1, ..., nameN) or cfg(name1, ..., nameN, values())
 - cfg(any())

It also changes the default exhaustiveness to be enable-by-default in
the presence of any --check-cfg arguments.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index 199b5d69a1c..41602dec44c 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -628,10 +628,10 @@ Using this flag looks like this:
 
 ```bash
 $ rustdoc src/lib.rs -Z unstable-options \
-    --check-cfg='names()' --check-cfg='values(feature, "foo", "bar")'
+    --check-cfg='cfg(feature, values("foo", "bar"))'
 ```
 
-The example above check every well known names (`target_os`, `doc`, `test`, ... via `names()`)
+The example above check every well known names and values (`target_os`, `doc`, `test`, ...)
 and check the values of `feature`: `foo` and `bar`.
 
 ### `--generate-link-to-definition`: Generate links on types in source code