Merge pull request #890 from Microsoft/sigHelpCrash

Fix signature help crash when requested outside argument list

src/services/formatting/smartIndenter.ts

@@ -108,7 +108,7 @@ module ts.formatting {
         function getActualIndentationForListItemBeforeComma(commaToken: Node, sourceFile: SourceFile, options: TypeScript.FormattingOptions): number {
             // previous token is comma that separates items in list - find the previous item and try to derive indentation from it
             var commaItemInfo = findListItemInfo(commaToken);
-            Debug.assert(commaItemInfo.listItemIndex > 0);
+            Debug.assert(commaItemInfo && commaItemInfo.listItemIndex > 0);
             // The item we're interested in is right before the comma
             return deriveActualIndentationFromList(commaItemInfo.list.getChildren(), commaItemInfo.listItemIndex - 1, sourceFile, options);
         }

src/services/signatureHelp.ts

@@ -226,12 +226,12 @@ module ts.SignatureHelp {
                 };
             }
 
-            if (node.kind === SyntaxKind.GreaterThanToken
-                || node.kind === SyntaxKind.CloseParenToken
-                || node === parent.func) {
-                return undefined;
-            }
-
+            // findListItemInfo can return undefined if we are not in parent's argument list
+            // or type argument list. This includes cases where the cursor is:
+            //   - To the right of the closing paren
+            //   - Between the type arguments and the arguments (greater than token)
+            //   - On the target of the call (parent.func)
+            //   - On the 'new' keyword in a 'new' expression
             return findListItemInfo(node);
         }
 

src/services/utilities.ts

@@ -7,6 +7,15 @@ module ts {
 
     export function findListItemInfo(node: Node): ListItemInfo {
         var syntaxList = findContainingList(node);
+
+        // It is possible at this point for syntaxList to be undefined, either if
+        // node.parent had no list child, or if none of its list children contained
+        // the span of node. If this happens, return undefined. The caller should
+        // handle this case.
+        if (!syntaxList) {
+            return undefined;
+        }
+
         var children = syntaxList.getChildren();
         var index = indexOf(children, node);
 
@@ -32,13 +41,6 @@ module ts {
             }
         });
 
-        // syntaxList should not be undefined here. If it is, there is a problem. Find out if
-        // there at least is a child that is a list.
-        if (!syntaxList) {
-            Debug.assert(findChildOfKind(node.parent, SyntaxKind.SyntaxList),
-                "Node of kind " + SyntaxKind[node.parent.kind] + " has no list children");
-        }
-
         return syntaxList;
     }
 

tests/cases/fourslash/noSignatureHelpOnNewKeyword.ts

@@ -0,0 +1,14 @@
+///<reference path="fourslash.ts"/>
+
+////class Foo { }
+////new/*1*/ Foo
+////new /*2*/Foo(/*3*/)
+
+goTo.marker('1');
+verify.not.signatureHelpPresent();
+
+goTo.marker('2');
+verify.not.signatureHelpPresent();
+
+goTo.marker('3');
+verify.signatureHelpPresent();