[regexp] break recursion in mutually recursive capture/back references.

src/ast/ast.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_AST_AST_H_
 #define V8_AST_AST_H_
 
 #include "src/assembler.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/modules.h"
@@ skipping 3168 matching lines @@
 
 class RegExpBackReference final : public RegExpTree {
  public:
   explicit RegExpBackReference(RegExpCapture* capture)
       : capture_(capture) { }
   void* Accept(RegExpVisitor* visitor, void* data) override;
   RegExpNode* ToNode(RegExpCompiler* compiler, RegExpNode* on_success) override;
   RegExpBackReference* AsBackReference() override;
   bool IsBackReference() override;
   int min_match() override { return 0; }
-  // The capture may not be completely parsed yet, if the reference occurs
-  // before the capture. In the ordinary case, nothing has been captured yet,
-  // so the back reference must have the length 0. If the back reference is
-  // inside a lookbehind, effectively making it a forward reference, we return
-  // 0 since lookbehinds have a length of 0.
-  int max_match() override {
-    return capture_->body() ? capture_->max_match() : 0;
-  }
+  // The back reference may be recursive, e.g. /(\2)(\1)/. To avoid infinite
+  // recursion, we give up. Ignorance is bliss.
+  int max_match() override { return kInfinity; }
   int index() { return capture_->index(); }
   RegExpCapture* capture() { return capture_; }
  private:
   RegExpCapture* capture_;
 };
 
 
 class RegExpEmpty final : public RegExpTree {
  public:
   RegExpEmpty() { }
@@ skipping 508 matching lines @@
   // the parser-level zone.
   Zone* parser_zone_;
   AstValueFactory* ast_value_factory_;
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_AST_H_