address requested changes

compiler/rustc_lint/messages.ftl

@@ -240,7 +240,10 @@ lint_hidden_unicode_codepoints = unicode codepoint changing visible direction of
 
 lint_identifier_non_ascii_char = identifier contains non-ASCII characters
 
-lint_identifier_uncommon_codepoints = identifier contains uncommon Unicode codepoints: {$codepoints}
+lint_identifier_uncommon_codepoints = identifier contains {$codepoints_len -> 
+    [one] an uncommon Unicode codepoint
+    *[other] uncommon Unicode codepoints
+}: {$codepoints}
 
 lint_ignored_unless_crate_specified = {$level}({$name}) is ignored unless specified at crate level
 

compiler/rustc_lint/src/lints.rs

@@ -1109,6 +1109,7 @@ pub struct IdentifierNonAsciiChar;
 #[diag(lint_identifier_uncommon_codepoints)]
 pub struct IdentifierUncommonCodepoints {
     pub codepoints: Vec<char>,
+    pub codepoints_len: usize,
 }
 
 #[derive(LintDiagnostic)]

compiler/rustc_lint/src/non_ascii_idents.rs

@@ -190,15 +190,16 @@ impl EarlyLintPass for NonAsciiIdents {
             if check_uncommon_codepoints
                 && !symbol_str.chars().all(GeneralSecurityProfile::identifier_allowed)
             {
+                let codepoints: Vec<_> = symbol_str
+                    .chars()
+                    .filter(|c| !GeneralSecurityProfile::identifier_allowed(*c))
+                    .collect();
+                let codepoints_len = codepoints.len();
+
                 cx.emit_span_lint(
                     UNCOMMON_CODEPOINTS,
                     sp,
-                    IdentifierUncommonCodepoints {
-                        codepoints: symbol_str
-                            .chars()
-                            .filter(|c| !GeneralSecurityProfile::identifier_allowed(*c))
-                            .collect(),
-                    },
+                    IdentifierUncommonCodepoints { codepoints, codepoints_len },
                 );
             }
         }