Fix Behavior Related to namedCaptureGroups

Author: graphemecluster

src/compiler/scanner.ts

@@ -2490,7 +2490,8 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
                     inCharacterClass = false;
                 }
                 else if (
-                    ch === CharacterCodes.openParen
+                    !inCharacterClass
+                    && ch === CharacterCodes.openParen
                     && charCodeChecked(pos + 1) === CharacterCodes.question
                     && charCodeChecked(pos + 2) === CharacterCodes.lessThan
                     && charCodeChecked(pos + 3) !== CharacterCodes.equals
@@ -2877,7 +2878,7 @@ export function createScanner(languageVersion: ScriptTarget, skipTrivia: boolean
                         scanGroupName(/*isReference*/ true);
                         scanExpectedChar(CharacterCodes.greaterThan);
                     }
-                    else if (namedCaptureGroups) {
+                    else if (anyUnicodeModeOrNonAnnexB || namedCaptureGroups) {
                         error(Diagnostics.k_must_be_followed_by_a_capturing_group_name_enclosed_in_angle_brackets, pos - 2, 2);
                     }
                     break;

tests/baselines/reference/regularExpressionAnnexB.errors.txt

@@ -7,6 +7,7 @@ regularExpressionAnnexB.ts(3,29): error TS1125: Hexadecimal digit expected.
 regularExpressionAnnexB.ts(7,4): error TS1535: This character cannot be escaped in a regular expression.
 regularExpressionAnnexB.ts(7,8): error TS1125: Hexadecimal digit expected.
 regularExpressionAnnexB.ts(7,10): error TS1512: '\c' must be followed by an ASCII letter.
+regularExpressionAnnexB.ts(7,12): error TS1510: '\k' must be followed by a capturing group name enclosed in angle brackets.
 regularExpressionAnnexB.ts(7,14): error TS1535: This character cannot be escaped in a regular expression.
 regularExpressionAnnexB.ts(7,18): error TS1535: This character cannot be escaped in a regular expression.
 regularExpressionAnnexB.ts(7,22): error TS1125: Hexadecimal digit expected.
@@ -73,7 +74,7 @@ regularExpressionAnnexB.ts(42,5): error TS1506: Numbers out of order in quantifi
 regularExpressionAnnexB.ts(42,10): error TS1507: There is nothing available for repetition.
 
 
-==== regularExpressionAnnexB.ts (73 errors) ====
+==== regularExpressionAnnexB.ts (74 errors) ====
     const regexes: RegExp[] = [
       /\q\u\i\c\k\_\f\o\x\-\j\u\m\p\s/,
 
@@ -99,6 +100,8 @@ regularExpressionAnnexB.ts(42,10): error TS1507: There is nothing available for
 !!! error TS1125: Hexadecimal digit expected.
              ~~
 !!! error TS1512: '\c' must be followed by an ASCII letter.
+               ~~
+!!! error TS1510: '\k' must be followed by a capturing group name enclosed in angle brackets.
                  ~~
 !!! error TS1535: This character cannot be escaped in a regular expression.
                      ~~