From 6389474709779cb02ef61ec705db2223ddeb8896 Mon Sep 17 00:00:00 2001
From: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
Date: Sun, 7 Feb 2016 17:03:06 -0500
Subject: [PATCH 1/2] update lib

---
 lib/lexer.js | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/lib/lexer.js b/lib/lexer.js
index a0a62434d..38a2ea00b 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -900,11 +900,6 @@ exports.doLiteral = function(code, index){
     }
     tag = 'UNARY';
     break;
-  case '&':
-    if (!able(this.tokens)) {
-      tag = 'LITERAL';
-    }
-    break;
   case '|':
     tag = 'BITWISE';
     break;

From 4a207180f4f4613be1d6de83e441b37b2b1ae3d4 Mon Sep 17 00:00:00 2001
From: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
Date: Sun, 7 Feb 2016 17:12:34 -0500
Subject: [PATCH 2/2] add robustness to generated loop code

Certain expressions--integers (with or without a preceding +/-), null,
and void--when used as sources of for loops resulted in illegal
JavaScript being generated. While (42).length is a silly but legal thing
to do, 42.length is an actual SyntaxError in JS. This commit adds checks
to wrap potentially problematic expressions in parentheses.
---
 lib/ast.js   | 12 ++++++++----
 src/ast.ls   |  8 +++++---
 test/loop.ls | 10 ++++++++++
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/lib/ast.js b/lib/ast.js
index 79c9dc90a..a6f801be1 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -274,10 +274,14 @@ SourceNode::to-string = (...args) ->
       return [sub, ref, [ref.value]];
     }
   },
-  compileLoopReference: function(o, name, ret){
-    var ref$, asn, tmp;
+  compileLoopReference: function(o, name, ret, safeAccess){
+    var ref$, code, asn, tmp;
     if (this instanceof Var && o.scope.check(this.value) || this instanceof Unary && ((ref$ = this.op) === '+' || ref$ === '-') && (-1 / 0 < (ref$ = +this.it.value) && ref$ < 1 / 0) || this instanceof Literal && !this.isComplex()) {
-      return [ref$ = this.compile(o), ref$];
+      code = this.compile(o, LEVEL_PAREN);
+      if (safeAccess && !(this instanceof Var)) {
+        code = "(" + code + ")";
+      }
+      return [code, code];
     }
     asn = Assign(Var(tmp = o.scope.temporary(name)), this);
     ret || (asn['void'] = true);
@@ -3695,7 +3699,7 @@ exports.For = For = (function(superclass){
         this.item = Var(o.scope.temporary('x'));
       }
       if (this.item || this.object && this.own || this['let']) {
-        ref$ = this.source.compileLoopReference(o, 'ref', !this.object), svar = ref$[0], srcPart = ref$[1];
+        ref$ = this.source.compileLoopReference(o, 'ref', !this.object, true), svar = ref$[0], srcPart = ref$[1];
         svar === srcPart || temps.push(svar);
       } else {
         svar = srcPart = this.source.compile(o, LEVEL_PAREN);
diff --git a/src/ast.ls b/src/ast.ls
index dd9d98472..3cf6c3e1a 100644
--- a/src/ast.ls
+++ b/src/ast.ls
@@ -199,11 +199,13 @@ SourceNode::to-string = (...args) ->
         if once then [sub, ref <<< {+temp}] else [sub, ref, [ref.value]]
 
     # Compiles to a variable/source pair suitable for looping.
-    compile-loop-reference: (o, name, ret) ->
+    compile-loop-reference: (o, name, ret, safe-access) ->
         if this instanceof Var   and o.scope.check @value
         or this instanceof Unary and @op in <[ + - ]> and -1/0 < +@it.value < 1/0
         or this instanceof Literal and not @is-complex!
-            return [@compile o] * 2
+            code = @compile o, LEVEL_PAREN
+            code = "(#code)" if safe-access and this not instanceof Var
+            return [code] * 2
         asn = Assign Var(tmp = o.scope.temporary name), this
         ret or asn.void = true
         [tmp; asn.compile o, if ret then LEVEL_CALL else LEVEL_PAREN]
@@ -2352,7 +2354,7 @@ class exports.For extends While
         else
             @item = Var o.scope.temporary \x if @ref
             if @item or @object and @own or @let
-                [svar, srcPart] = @source.compile-loop-reference o, \ref, not @object
+                [svar, srcPart] = @source.compile-loop-reference o, \ref, not @object, true
                 svar is srcPart or temps.push svar
             else
                 svar = srcPart = @source.compile o, LEVEL_PAREN
diff --git a/test/loop.ls b/test/loop.ls
index 5ff9939a2..6f3b03365 100644
--- a/test/loop.ls
+++ b/test/loop.ls
@@ -686,3 +686,13 @@ eq 1, i
 o = { [k, -> v] for let k, v of {a: 1, b: 2} }
 eq 1 o.a!
 eq 2 o.b!
+
+# Certain literals could result in illegal JavaScript if not carefully
+# handled. These are all nonsensical use cases and could just as easily
+# be LiveScript syntax errors. The thing to avoid is for them to be JavaScript
+# syntax errors; lsc should never produce illegal JavaScript on any input,
+# silly or otherwise.
+deep-equal [] [0 for x in 42]
+deep-equal [] [0 for x in -42]
+throws "Cannot read property 'length' of null" -> [0 for x in null]
+throws "Cannot read property 'length' of undefined" -> [0 for x in void]