Merge pull request github#11234 from jketema/std-iterator-fix

C++: Recognize `basic_string::iterator` as an iterator

Author: jketema

cpp/ql/lib/semmle/code/cpp/models/implementations/StdString.qll

@@ -15,6 +15,15 @@ private class StdBasicString extends ClassTemplateInstantiation {
   StdBasicString() { this.hasQualifiedName(["std", "bsl"], "basic_string") }
 }
 
+/**
+ * The `std::basic_string::iterator` declaration.
+ */
+private class StdBasicStringIterator extends Iterator, Type {
+  StdBasicStringIterator() {
+    this.getEnclosingElement() instanceof StdBasicString and this.hasName("iterator")
+  }
+}
+
 /**
  * A `std::string` function for which taint should be propagated.
  */