Fix #1726: expression in property access causes unexpected results (#…

…4851) * fix #1726 * Explain what's happening, rather than just linking to an issue * Updated output * Optimization
jashkenas · Jan 16, 2018 · 0217ed5 · 0217ed5
1 parent e53307b
commit 0217ed5
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Showing 3 changed files with 22 additions and 6 deletions.
diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
diff --git a/src/nodes.coffee b/src/nodes.coffee
@@ -1406,8 +1406,12 @@ exports.Slice = class Slice extends Base
   # `9e9` should be safe because `9e9` > `2**32`, the max array length.
   compileNode: (o) ->
     {to, from} = @range
-    fromCompiled = from and from.compileToFragments(o, LEVEL_PAREN) or [@makeCode '0']
-    # TODO: jwalton - move this into the 'if'?
+    # Handle an expression in the property access, e.g. `a[!b in c..]`.
+    if from?.shouldCache()
+      from = new Value new Parens from
+    if to?.shouldCache()
+      to = new Value new Parens to
+    fromCompiled = from?.compileToFragments(o, LEVEL_PAREN) or [@makeCode '0']
     if to
       compiled     = to.compileToFragments o, LEVEL_PAREN
       compiledText = fragmentsToText compiled

diff --git a/test/slicing_and_splicing.coffee b/test/slicing_and_splicing.coffee
@@ -165,3 +165,9 @@ test "#2953: methods on endpoints in assignment from array splice literal", ->
   delete Number.prototype.same
 
   arrayEq [0, 5, 9], list
+
+test "#1726: `Op` expression in property access causes unexpected results", ->
+  a = [0..2]
+  arrayEq a, a[(!1 in a)..]
+  arrayEq a, a[!1 in a..]
+  arrayEq a[(!1 in a)..], a[(!1 in a)..]