Rollup merge of #72259 - crlf0710:ascii_only_check, r=petrochenkov

Disallow forbidden usage of non-ascii identifiers.

Part of RFC2457, this tightens allowed identifiers back to ascii only in two situations.

r? @petrochenkov

2 files changed, 34 insertions, 0 deletions

diff --git a/src/librustc_error_codes/error_codes.rs b/src/librustc_error_codes/error_codes.rs
index 2399e99a309..d6863c615f6 100644
--- a/src/librustc_error_codes/error_codes.rs
+++ b/src/librustc_error_codes/error_codes.rs
@@ -436,6 +436,7 @@ E0750: include_str!("./error_codes/E0750.md"),
 E0751: include_str!("./error_codes/E0751.md"),
 E0752: include_str!("./error_codes/E0752.md"),
 E0753: include_str!("./error_codes/E0753.md"),
+E0754: include_str!("./error_codes/E0754.md"),
 ;
 //  E0006, // merged with E0005
 //  E0008, // cannot bind by-move into a pattern guard
diff --git a/src/librustc_error_codes/error_codes/E0754.md b/src/librustc_error_codes/error_codes/E0754.md
new file mode 100644
index 00000000000..abdc01ed21a
--- /dev/null
+++ b/src/librustc_error_codes/error_codes/E0754.md
@@ -0,0 +1,33 @@
+An non-ascii identifier was used in an invalid context.
+
+Erroneous code example:
+
+```compile_fail,E0754
+# #![feature(non_ascii_idents)]
+
+mod řųśť;
+// ^ error!
+fn main() {}
+```
+
+```compile_fail,E0754
+# #![feature(non_ascii_idents)]
+
+#[no_mangle]
+fn řųśť() {}
+// ^ error!
+fn main() {}
+```
+
+Non-ascii can be used as module names if it is inline
+or a #\[path\] attribute is specified. For example:
+
+```
+# #![feature(non_ascii_idents)]
+
+mod řųśť {
+    const IS_GREAT: bool = true;
+}
+
+fn main() {}
+```