fix(linter/no-control-regex): better diagnostic messages (#6530)

1. Handle plural/singular cases in message and help text
2. Shrink spans in `RegExp` constructors to only cover the regular expression itself.

crates/oxc_linter/src/rules/eslint/no_control_regex.rs

@@ -12,10 +12,15 @@ use oxc_span::{GetSpan, Span};
 
 use crate::{ast_util::extract_regex_flags, context::LintContext, rule::Rule, AstNode};
 
-fn no_control_regex_diagnostic(regex: &str, span: Span) -> OxcDiagnostic {
-    OxcDiagnostic::warn("Unexpected control character(s)")
-        .with_help(format!("Unexpected control character(s) in regular expression: \"{regex}\""))
-        .with_label(span)
+fn no_control_regex_diagnostic(count: usize, regex: &str, span: Span) -> OxcDiagnostic {
+    debug_assert!(count > 0);
+    let (message, help) = if count == 1 {
+        ("Unexpected control character", format!("'{regex}' is not a valid control character."))
+    } else {
+        ("Unexpected control characters", format!("'{regex}' are not valid control characters."))
+    };
+
+    OxcDiagnostic::warn(message).with_help(help).with_label(span)
 }
 
 #[derive(Debug, Default, Clone)]
@@ -89,7 +94,12 @@ impl Rule for NoControlRegex {
                     if let Argument::StringLiteral(pattern) = &expr.arguments[0] {
                         // get pattern from arguments. Missing or non-string arguments
                         // will be runtime errors, but are not covered by this rule.
-                        parse_and_check_regex(context, &pattern.value, &expr.arguments, expr.span);
+                        parse_and_check_regex(
+                            context,
+                            &pattern.value,
+                            &expr.arguments,
+                            pattern.span,
+                        );
                     }
                 }
             }
@@ -107,7 +117,12 @@ impl Rule for NoControlRegex {
                     if let Argument::StringLiteral(pattern) = &expr.arguments[0] {
                         // get pattern from arguments. Missing or non-string arguments
                         // will be runtime errors, but are not covered by this rule.
-                        parse_and_check_regex(context, &pattern.value, &expr.arguments, expr.span);
+                        parse_and_check_regex(
+                            context,
+                            &pattern.value,
+                            &expr.arguments,
+                            pattern.span,
+                        );
                     }
                 }
             }
@@ -143,8 +158,9 @@ fn check_pattern(context: &LintContext, pattern: &Pattern, span: Span) {
     finder.visit_pattern(pattern);
 
     if !finder.control_chars.is_empty() {
+        let num_control_chars = finder.control_chars.len();
         let violations = finder.control_chars.into_iter().map(|c| c.to_string()).join(", ");
-        context.diagnostic(no_control_regex_diagnostic(&violations, span));
+        context.diagnostic(no_control_regex_diagnostic(num_control_chars, &violations, span));
     }
 }
 

crates/oxc_linter/src/snapshots/no_control_regex@capture-group-indexing.snap

@@ -1,30 +1,30 @@
 ---
 source: crates/oxc_linter/src/tester.rs
 ---
-  ⚠ eslint(no-control-regex): Unexpected control character(s)
+  ⚠ eslint(no-control-regex): Unexpected control character
    ╭─[no_control_regex.tsx:1:11]
  1 │ const r = /\0/;
    ·           ────
    ╰────
-  help: Unexpected control character(s) in regular expression: "\0"
+  help: '\0' is not a valid control character.
 
-  ⚠ eslint(no-control-regex): Unexpected control character(s)
+  ⚠ eslint(no-control-regex): Unexpected control character
    ╭─[no_control_regex.tsx:1:11]
  1 │ const r = /[a-z]\1/;
    ·           ─────────
    ╰────
-  help: Unexpected control character(s) in regular expression: "\1"
+  help: '\1' is not a valid control character.
 
-  ⚠ eslint(no-control-regex): Unexpected control character(s)
+  ⚠ eslint(no-control-regex): Unexpected control character
    ╭─[no_control_regex.tsx:1:11]
  1 │ const r = /([a-z])\2/;
    ·           ───────────
    ╰────
-  help: Unexpected control character(s) in regular expression: "\2"
+  help: '\2' is not a valid control character.
 
-  ⚠ eslint(no-control-regex): Unexpected control character(s)
+  ⚠ eslint(no-control-regex): Unexpected control character
    ╭─[no_control_regex.tsx:1:11]
  1 │ const r = /([a-z])\0/;
    ·           ───────────
    ╰────
-  help: Unexpected control character(s) in regular expression: "\0"
+  help: '\0' is not a valid control character.