Handle malformed types in catch-on.

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 4456 matching lines @@
       pushInvokeHelper1(
           backend.getExceptionUnwrapper(), exception, HType.UNKNOWN);
       HInvokeStatic unwrappedException = pop();
       tryInstruction.exception = exception;
       Link<Node> link = node.catchBlocks.nodes;
 
       void pushCondition(CatchBlock catchBlock) {
         if (catchBlock.onKeyword != null) {
           DartType type = elements.getType(catchBlock.type);
           if (type == null) {
-            compiler.cancel('On with unresolved type',
-                            node: catchBlock.type);
+            compiler.internalError('On with no type', node: catchBlock.type);
           }
-          HInstruction condition =
-              new HIs(type, <HInstruction>[unwrappedException]);
-          push(condition);
-        }
-        else {
+          if (type.isMalformed) {
+            // TODO(johnniwinther): Handle malformed types in [HIs] instead.
+            HInstruction condition =
+                graph.addConstantBool(true, constantSystem);
+            stack.add(condition);
+          } else {
+            HInstruction condition =
+                new HIs(type, <HInstruction>[unwrappedException]);
+            push(condition);
+          }
+        } else {
           VariableDefinitions declaration = catchBlock.formals.nodes.head;
           HInstruction condition = null;
           if (declaration.type == null) {
             condition = graph.addConstantBool(true, constantSystem);
             stack.add(condition);
           } else {
             // TODO(aprelev@gmail.com): Once old catch syntax is removed
             // "if" condition above and this "else" branch should be deleted as
             // type of declared variable won't matter for the catch
             // condition.
             DartType type = elements.getType(declaration.type);
             if (type == null) {
               compiler.cancel('Catch with unresolved type', node: catchBlock);
             }
             condition =
                 new HIs(type, <HInstruction>[unwrappedException], nullOk: true);
             push(condition);
           }
         }
       }
 
       void visitThen() {
         CatchBlock catchBlock = link.head;
         link = link.tail;
+
+        if (compiler.enableTypeAssertions) {
+          // In checked mode: throw a type error if the on-catch type is
+          // malformed.
+          if (catchBlock.onKeyword != null) {
+            DartType type = elements.getType(catchBlock.type);
+            if (type != null && type.isMalformed) {
+              String reasons = Types.fetchReasonsFromMalformedType(type);
+              generateMalformedSubtypeError(node,
+                  unwrappedException, type, reasons);
+              pop();
+              return;
+            }
+          }
+        }
         if (catchBlock.exception != null) {
           localsHandler.updateLocal(elements[catchBlock.exception],
                                     unwrappedException);
         }
         Node trace = catchBlock.trace;
         if (trace != null) {
           pushInvokeHelper1(
               backend.getTraceFromException(), exception, HType.UNKNOWN);
           HInstruction traceInstruction = pop();
           localsHandler.updateLocal(elements[trace], traceInstruction);
@@ skipping 553 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }