Support comma operator in type guards

ahejlsberg · ahejlsberg · commit ea96dfd364f7 · 2016-04-20T06:59:28.000-07:00
diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
@@ -630,6 +630,8 @@ namespace ts {
                     return false;
                 case SyntaxKind.InstanceOfKeyword:
                     return isNarrowingExpression(expr.left);
+                case SyntaxKind.CommaToken:
+                    return isNarrowingExpression(expr.right);
             }
             return false;
         }
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -7677,6 +7677,8 @@ namespace ts {
                         break;
                     case SyntaxKind.InstanceOfKeyword:
                         return narrowTypeByInstanceof(type, expr, assumeTrue);
+                    case SyntaxKind.CommaToken:
+                        return narrowType(type, expr.right, assumeTrue);
                 }
                 return type;
             }

Original file line number	Diff line number	Diff line change
`@@ -630,6 +630,8 @@ namespace ts {`
`630`	`630`	`return false;`
`631`	`631`	`case SyntaxKind.InstanceOfKeyword:`
`632`	`632`	`return isNarrowingExpression(expr.left);`
	`633`	`+ case SyntaxKind.CommaToken:`
	`634`	`+ return isNarrowingExpression(expr.right);`
`633`	`635`	`}`
`634`	`636`	`return false;`
`635`	`637`	`}`
Original file line number	Diff line number	Diff line change
`@@ -7677,6 +7677,8 @@ namespace ts {`
`7677`	`7677`	`break;`
`7678`	`7678`	`case SyntaxKind.InstanceOfKeyword:`
`7679`	`7679`	`return narrowTypeByInstanceof(type, expr, assumeTrue);`
	`7680`	`+ case SyntaxKind.CommaToken:`
	`7681`	`+ return narrowType(type, expr.right, assumeTrue);`
`7680`	`7682`	`}`
`7681`	`7683`	`return type;`
`7682`	`7684`	`}`