From 1ecf21f22b30a9865708fab193568a830cbdd10a Mon Sep 17 00:00:00 2001
From: jan <jan@fb.com>
Date: Wed, 13 Mar 2013 20:41:17 -0700
Subject: [PATCH] ListAssignment: define RHS kind explicitly for all expression
 types

It's easy to introduce bug by adding a new expression and not defining
its ListAssignment RHS kind. Add all expression types explicitly and
remove default case so that it becomes compile time error if the list is
not updated.
---
 hphp/compiler/expression/list_assignment.cpp | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/hphp/compiler/expression/list_assignment.cpp b/hphp/compiler/expression/list_assignment.cpp
index 675d70636..e5c5c3a8b 100644
--- a/hphp/compiler/expression/list_assignment.cpp
+++ b/hphp/compiler/expression/list_assignment.cpp
@@ -73,6 +73,7 @@ static ListAssignment::RHSKind GetRHSKind(ExpressionPtr rhs) {
     case Expression::KindOfObjectMethodExpression:
     case Expression::KindOfNewObjectExpression:
     case Expression::KindOfAssignmentExpression:
+    case Expression::KindOfExpressionList:
     case Expression::KindOfIncludeExpression:
       return ListAssignment::Regular;
 
@@ -106,9 +107,24 @@ static ListAssignment::RHSKind GetRHSKind(ExpressionPtr rhs) {
     case Expression::KindOfQOpExpression:
       return ListAssignment::Checked;
 
-    default: break;
+    // invalid context
+    case Expression::KindOfArrayPairExpression:
+    case Expression::KindOfParameterExpression:
+    case Expression::KindOfModifierExpression:
+    case Expression::KindOfUserAttribute:
+      always_assert(false);
+
+    // non-arrays
+    case Expression::KindOfScalarExpression:
+    case Expression::KindOfConstantExpression:
+    case Expression::KindOfClassConstantExpression:
+    case Expression::KindOfEncapsListExpression:
+    case Expression::KindOfClosureExpression:
+      return ListAssignment::Null;
   }
-  return ListAssignment::Null;
+
+  // unreachable for known expression kinds
+  always_assert(false);
 }
 
 static bool AssignmentCouldSet(ExpressionListPtr vars, ExpressionPtr var) {