Try optional catch binding

src/org/mozilla/javascript/CodeGenerator.java

@@ -473,7 +473,7 @@ private void visitStatement(Node node, int initialStackDepth) {
                 {
                     int localIndex = getLocalBlockRef(node);
                     int scopeIndex = node.getExistingIntProp(Node.CATCH_SCOPE_PROP);
-                    String name = child.getString();
+                    String name = child.getType() == Token.NAME ? child.getString() : "";
                     child = child.getNext();
                     visitExpression(child, 0); // load expression object
                     addStringPrefix(name);

src/org/mozilla/javascript/IRFactory.java

@@ -1236,27 +1236,34 @@ private Node transformTry(TryStatement node) {
         Node catchBlocks = new Block();
         for (CatchClause cc : node.getCatchClauses()) {
             decompiler.addToken(Token.CATCH);
-            decompiler.addToken(Token.LP);
-
-            String varName = cc.getVarName().getIdentifier();
-            decompiler.addName(varName);
 
+            Name varName = cc.getVarName();
             Node catchCond = null;
-            AstNode ccc = cc.getCatchCondition();
-            if (ccc != null) {
-                decompiler.addName(" ");
-                decompiler.addToken(Token.IF);
-                catchCond = transform(ccc);
-            } else {
-                catchCond = new EmptyExpression();
+            Node varNameNode = null;
+
+            if (varName != null) {
+                decompiler.addToken(Token.LP);
+                decompiler.addName(varName.getIdentifier());
+
+                varNameNode = createName(varName.getIdentifier());
+
+                AstNode ccc = cc.getCatchCondition();
+                if (ccc != null) {
+                    decompiler.addName(" ");
+                    decompiler.addToken(Token.IF);
+                    catchCond = transform(ccc);
+                } else {
+                    catchCond = new EmptyExpression();
+                }
+
+                decompiler.addToken(Token.RP);
             }
-            decompiler.addToken(Token.RP);
             decompiler.addEOL(Token.LC);
 
             Node body = transform(cc.getBody());
             decompiler.addEOL(Token.RC);
 
-            catchBlocks.addChildToBack(createCatch(varName, catchCond, body, cc.getLineno()));
+            catchBlocks.addChildToBack(createCatch(varNameNode, catchCond, body, cc.getLineno()));
         }
         Node finallyBlock = null;
         if (node.getFinallyBlock() != null) {
@@ -1529,11 +1536,14 @@ private static Node createString(String string) {
      * @param stmts the statements in the catch clause
      * @param lineno the starting line number of the catch clause
      */
-    private Node createCatch(String varName, Node catchCond, Node stmts, int lineno) {
+    private Node createCatch(Node varName, Node catchCond, Node stmts, int lineno) {
+        if (varName == null) {
+            varName = new Node(Token.EMPTY);
+        }
         if (catchCond == null) {
             catchCond = new Node(Token.EMPTY);
         }
-        return new Node(Token.CATCH, createName(varName), catchCond, stmts, lineno);
+        return new Node(Token.CATCH, varName, catchCond, stmts, lineno);
     }
 
     private static Node initFunction(

src/org/mozilla/javascript/Parser.java

@@ -1637,39 +1637,68 @@ private TryStatement tryStatement() throws IOException {
                     reportError("msg.catch.unreachable");
                 }
                 int catchPos = ts.tokenBeg, lp = -1, rp = -1, guardPos = -1;
-                if (mustMatchToken(Token.LP, "msg.no.paren.catch", true)) lp = ts.tokenBeg;
+                Name varName = null;
+                AstNode catchCond = null;
 
-                mustMatchToken(Token.NAME, "msg.bad.catchcond", true);
+                switch (peekToken()) {
+                    case Token.LP:
+                        {
+                            matchToken(Token.LP, true);
+                            lp = ts.tokenBeg;
+                            mustMatchToken(Token.NAME, "msg.bad.catchcond", true);
+
+                            varName = createNameNode();
+                            Comment jsdocNodeForName = getAndResetJsDoc();
+                            if (jsdocNodeForName != null) {
+                                varName.setJsDocNode(jsdocNodeForName);
+                            }
+                            String varNameString = varName.getIdentifier();
+                            if (inUseStrictDirective) {
+                                if ("eval".equals(varNameString)
+                                        || "arguments".equals(varNameString)) {
+                                    reportError("msg.bad.id.strict", varNameString);
+                                }
+                            }
 
-                Name varName = createNameNode();
-                Comment jsdocNodeForName = getAndResetJsDoc();
-                if (jsdocNodeForName != null) {
-                    varName.setJsDocNode(jsdocNodeForName);
-                }
-                String varNameString = varName.getIdentifier();
-                if (inUseStrictDirective) {
-                    if ("eval".equals(varNameString) || "arguments".equals(varNameString)) {
-                        reportError("msg.bad.id.strict", varNameString);
-                    }
-                }
+                            if (matchToken(Token.IF, true)) {
+                                guardPos = ts.tokenBeg;
+                                catchCond = expr();
+                            } else {
+                                sawDefaultCatch = true;
+                            }
 
-                AstNode catchCond = null;
-                if (matchToken(Token.IF, true)) {
-                    guardPos = ts.tokenBeg;
-                    catchCond = expr();
-                } else {
-                    sawDefaultCatch = true;
+                            if (mustMatchToken(Token.RP, "msg.bad.catchcond", true)) {
+                                rp = ts.tokenBeg;
+                            }
+                            mustMatchToken(Token.LC, "msg.no.brace.catchblock", true);
+                        }
+                        break;
+                    case Token.LC:
+                        if (compilerEnv.getLanguageVersion() >= Context.VERSION_ES6) {
+                            matchToken(Token.LC, true);
+                        } else {
+                            reportError("msg.no.paren.catch");
+                        }
+                        break;
+                    default:
+                        reportError("msg.no.paren.catch");
+                        break;
                 }
 
-                if (mustMatchToken(Token.RP, "msg.bad.catchcond", true)) rp = ts.tokenBeg;
-                mustMatchToken(Token.LC, "msg.no.brace.catchblock", true);
-
-                Block catchBlock = (Block) statements();
-                tryEnd = getNodeEnd(catchBlock);
+                Scope catchScope = new Scope(catchPos);
                 CatchClause catchNode = new CatchClause(catchPos);
+                catchNode.setLineno(ts.lineno);
+                pushScope(catchScope);
+                try {
+                    statements(catchScope);
+                } finally {
+                    popScope();
+                }
+
+                tryEnd = getNodeEnd(catchScope);
                 catchNode.setVarName(varName);
                 catchNode.setCatchCondition(catchCond);
-                catchNode.setBody(catchBlock);
+                catchNode.setBody(catchScope);
                 if (guardPos != -1) {
                     catchNode.setIfPosition(guardPos - catchPos);
                 }

src/org/mozilla/javascript/ScriptRuntime.java

@@ -4108,7 +4108,9 @@ public static Scriptable newCatchScope(
 
         NativeObject catchScopeObject = new NativeObject();
         // See ECMA 12.4
-        catchScopeObject.defineProperty(exceptionName, obj, ScriptableObject.PERMANENT);
+        if (exceptionName != null) {
+            catchScopeObject.defineProperty(exceptionName, obj, ScriptableObject.PERMANENT);
+        }
 
         if (isVisible(cx, t)) {
             // Add special Rhino object __exception__ defined in the catch

src/org/mozilla/javascript/ast/CatchClause.java

@@ -9,8 +9,7 @@
 import org.mozilla.javascript.Token;
 
 /**
- * Node representing a catch-clause of a try-statement.
- * Node type is {@link Token#CATCH}.
+ * Node representing a catch-clause of a try-statement. Node type is {@link Token#CATCH}.
  *
  * <pre><i>CatchClause</i> :
  *        <b>catch</b> ( <i><b>Identifier</b></i> [<b>if</b> Expression] ) Block</pre>
@@ -19,7 +18,7 @@ public class CatchClause extends AstNode {
 
     private Name varName;
     private AstNode catchCondition;
-    private Block body;
+    private Scope body;
     private int ifPosition = -1;
     private int lp = -1;
     private int rp = -1;
@@ -28,8 +27,7 @@ public class CatchClause extends AstNode {
         type = Token.CATCH;
     }
 
-    public CatchClause() {
-    }
+    public CatchClause() {}
 
     public CatchClause(int pos) {
         super(pos);
@@ -41,6 +39,7 @@ public CatchClause(int pos, int len) {
 
     /**
      * Returns catch variable node
+     *
      * @return catch variable
      */
     public Name getVarName() {
@@ -49,17 +48,19 @@ public Name getVarName() {
 
     /**
      * Sets catch variable node, and sets its parent to this node.
+     *
      * @param varName catch variable
-     * @throws IllegalArgumentException if varName is {@code null}
      */
     public void setVarName(Name varName) {
-        assertNotNull(varName);
         this.varName = varName;
-        varName.setParent(this);
+        if (varName != null) {
+            varName.setParent(this);
+        }
     }
 
     /**
      * Returns catch condition node, if present
+     *
      * @return catch condition node, {@code null} if not present
      */
     public AstNode getCatchCondition() {
@@ -68,69 +69,61 @@ public AstNode getCatchCondition() {
 
     /**
      * Sets catch condition node, and sets its parent to this node.
-     * @param catchCondition catch condition node.  Can be {@code null}.
+     *
+     * @param catchCondition catch condition node. Can be {@code null}.
      */
     public void setCatchCondition(AstNode catchCondition) {
         this.catchCondition = catchCondition;
-        if (catchCondition != null)
+        if (catchCondition != null) {
             catchCondition.setParent(this);
+        }
     }
 
-    /**
-     * Returns catch body
-     */
-    public Block getBody() {
+    /** Returns catch body */
+    public Scope getBody() {
         return body;
     }
 
     /**
      * Sets catch body, and sets its parent to this node.
+     *
      * @throws IllegalArgumentException if body is {@code null}
      */
-    public void setBody(Block body) {
+    public void setBody(Scope body) {
         assertNotNull(body);
         this.body = body;
         body.setParent(this);
     }
 
-    /**
-     * Returns left paren position
-     */
+    /** Returns left paren position */
     public int getLp() {
         return lp;
     }
 
-    /**
-     * Sets left paren position
-     */
+    /** Sets left paren position */
     public void setLp(int lp) {
         this.lp = lp;
     }
 
-    /**
-     * Returns right paren position
-     */
+    /** Returns right paren position */
     public int getRp() {
         return rp;
     }
 
-    /**
-     * Sets right paren position
-     */
+    /** Sets right paren position */
     public void setRp(int rp) {
         this.rp = rp;
     }
 
-    /**
-     * Sets both paren positions
-     */
+    /** Sets both paren positions */
     public void setParens(int lp, int rp) {
         this.lp = lp;
         this.rp = rp;
     }
 
     /**
      * Returns position of "if" keyword
+     *
      * @return position of "if" keyword, if present, or -1
      */
     public int getIfPosition() {
@@ -139,6 +132,7 @@ public int getIfPosition() {
 
     /**
      * Sets position of "if" keyword
+     *
      * @param ifPosition position of "if" keyword, if present, or -1
      */
     public void setIfPosition(int ifPosition) {
@@ -161,8 +155,8 @@ public String toSource(int depth) {
     }
 
     /**
-     * Visits this node, the catch var name node, the condition if
-     * non-{@code null}, and the catch body.
+     * Visits this node, the catch var name node, the condition if non-{@code null}, and the catch
+     * body.
      */
     @Override
     public void visit(NodeVisitor v) {

src/org/mozilla/javascript/optimizer/BodyCodegen.java

@@ -692,7 +692,10 @@ private void generateStatement(Node node) {
                     int local = getLocalBlockRegister(node);
                     int scopeIndex = node.getExistingIntProp(Node.CATCH_SCOPE_PROP);
 
-                    String name = child.getString(); // name of exception
+                    String name = null;
+                    if (child.getType() == Token.NAME) {
+                        name = child.getString(); // name of exception
+                    }
                     child = child.getNext();
                     generateExpression(child, node); // load expression object
                     if (scopeIndex == 0) {
@@ -701,7 +704,11 @@ private void generateStatement(Node node) {
                         // Load previous catch scope object
                         cfw.addALoad(local);
                     }
-                    cfw.addPush(name);
+                    if (name != null) {
+                        cfw.addPush(name);
+                    } else {
+                        cfw.add(ByteCode.ACONST_NULL);
+                    }
                     cfw.addALoad(contextLocal);
                     cfw.addALoad(variableObjectLocal);