Split Diagnostics for Uncommon Codepoints: Add List to Display Characters Involved

compiler/rustc_errors/src/diagnostic_impls.rs

@@ -110,6 +110,14 @@ impl IntoDiagnosticArg for char {
     }
 }
 
+impl IntoDiagnosticArg for Vec<char> {
+    fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
+        DiagnosticArgValue::StrListSepByAnd(
+            self.into_iter().map(|c| Cow::Owned(format!("{c:?}"))).collect(),
+        )
+    }
+}
+
 impl IntoDiagnosticArg for Symbol {
     fn into_diagnostic_arg(self) -> DiagnosticArgValue<'static> {
         self.to_ident_string().into_diagnostic_arg()

compiler/rustc_lint/messages.ftl

@@ -240,7 +240,7 @@ 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
+lint_identifier_uncommon_codepoints = identifier contains uncommon Unicode codepoints: {$codepoints}
 
 lint_ignored_unless_crate_specified = {$level}({$name}) is ignored unless specified at crate level
 

compiler/rustc_lint/src/lints.rs

@@ -1107,7 +1107,9 @@ pub struct IdentifierNonAsciiChar;
 
 #[derive(LintDiagnostic)]
 #[diag(lint_identifier_uncommon_codepoints)]
-pub struct IdentifierUncommonCodepoints;
+pub struct IdentifierUncommonCodepoints {
+    pub codepoints: Vec<char>,
+}
 
 #[derive(LintDiagnostic)]
 #[diag(lint_confusable_identifier_pair)]

compiler/rustc_lint/src/non_ascii_idents.rs

@@ -190,7 +190,16 @@ impl EarlyLintPass for NonAsciiIdents {
             if check_uncommon_codepoints
                 && !symbol_str.chars().all(GeneralSecurityProfile::identifier_allowed)
             {
-                cx.emit_span_lint(UNCOMMON_CODEPOINTS, sp, IdentifierUncommonCodepoints);
+                cx.emit_span_lint(
+                    UNCOMMON_CODEPOINTS,
+                    sp,
+                    IdentifierUncommonCodepoints {
+                        codepoints: symbol_str
+                            .chars()
+                            .filter(|c| !GeneralSecurityProfile::identifier_allowed(*c))
+                            .collect(),
+                    },
+                );
             }
         }
 

tests/ui/lexer/lex-emoji-identifiers.stderr

@@ -40,7 +40,7 @@ error: identifiers cannot contain emoji: `folded🙏🏿`
 LL |     let folded🙏🏿 = "modifier sequence";
    |         ^^^^^^^^^^
 
-warning: identifier contains uncommon Unicode codepoints
+warning: identifier contains uncommon Unicode codepoints: '\u{fe0f}'
   --> $DIR/lex-emoji-identifiers.rs:6:9
    |
 LL |     let key1️⃣ = "keycap sequence";

tests/ui/lint/rfc-2457-non-ascii-idents/lint-uncommon-codepoints.stderr

@@ -1,4 +1,4 @@
-error: identifier contains uncommon Unicode codepoints
+error: identifier contains uncommon Unicode codepoints: 'µ'
   --> $DIR/lint-uncommon-codepoints.rs:3:7
    |
 LL | const µ: f64 = 0.000001;
@@ -10,13 +10,13 @@ note: the lint level is defined here
 LL | #![deny(uncommon_codepoints)]
    |         ^^^^^^^^^^^^^^^^^^^
 
-error: identifier contains uncommon Unicode codepoints
+error: identifier contains uncommon Unicode codepoints: 'ij'
   --> $DIR/lint-uncommon-codepoints.rs:6:4
    |
 LL | fn dijkstra() {}
    |    ^^^^^^^
 
-error: identifier contains uncommon Unicode codepoints
+error: identifier contains uncommon Unicode codepoints: 'ㇻ', 'ㇲ', and 'ㇳ'
   --> $DIR/lint-uncommon-codepoints.rs:9:9
    |
 LL |     let ㇻㇲㇳ = "rust";