C++: Add ECMAScript std::regex parser

cpp/ql/lib/change-notes/2026-07-23-std-regex-ecmascript-parser.md

@@ -0,0 +1,4 @@
+---
+category: feature
+---
+* Added a C++ regular-expression parser for the ECMAScript grammar used by `std::regex`.

cpp/ql/lib/qlpack.yml

@@ -10,6 +10,7 @@ dependencies:
   codeql/mad: ${workspace}
   codeql/quantum: ${workspace}
   codeql/rangeanalysis: ${workspace}
+  codeql/regex: ${workspace}
   codeql/ssa: ${workspace}
   codeql/typeflow: ${workspace}
   codeql/tutorial: ${workspace}

cpp/ql/lib/semmle/code/cpp/exprs/Literal.qll

@@ -133,6 +133,19 @@ class StringLiteral extends TextLiteral {
   override string getAPrimaryQlClass() { result = "StringLiteral" }
 }
 
+/**
+ * A C++ raw string literal. For example:
+ * ```
+ * const char *s1 = R"(abcdef)";
+ * const wchar_t *s2 = LR"x(123456)x";
+ * ```
+ */
+class RawStringLiteral extends StringLiteral {
+  RawStringLiteral() { this.getValueText().regexpMatch("[^\"]*R\".*\\(.*") }
+
+  override string getAPrimaryQlClass() { result = "RawStringLiteral" }
+}
+
 /**
  * An octal literal. For example:
  * ```