fixes & improvements to [].join()

fixes
- [a].join() => "" + a
- ["a", , "b"].join() => "a,,b"
- ["a", null, "b"].join() => "a,,b"
- ["a", undefined, "b"].join() => "a,,b"

improvements
- ["a", "b"].join(null) => "anullb"
- ["a", "b"].join(undefined) => "a,b"
- [a + "b", c].join("") => a + "b" + c

closes #1453

1 files changed, 53 insertions, 0 deletions

diff --git a/test/compress/arrays.js b/test/compress/arrays.js
index 77ef761a..2e1f86ed 100644
--- a/test/compress/arrays.js
+++ b/test/compress/arrays.js
@@ -21,10 +21,19 @@ constant_join: {
     input: {
         var a = [ "foo", "bar", "baz" ].join("");
         var a1 = [ "foo", "bar", "baz" ].join();
+        var a2 = [ "foo", "bar", "baz" ].join(null);
+        var a3 = [ "foo", "bar", "baz" ].join(void 0);
+        var a4 = [ "foo", , "baz" ].join();
+        var a5 = [ "foo", null, "baz" ].join();
+        var a6 = [ "foo", void 0, "baz" ].join();
         var b = [ "foo", 1, 2, 3, "bar" ].join("");
         var c = [ boo(), "foo", 1, 2, 3, "bar", bar() ].join("");
         var c1 = [ boo(), bar(), "foo", 1, 2, 3, "bar", bar() ].join("");
         var c2 = [ 1, 2, "foo", "bar", baz() ].join("");
+        var c3 = [ boo() + bar() + "foo", 1, 2, 3, "bar", bar() + "foo" ].join("");
+        var c4 = [ 1, 2, null, undefined, "foo", "bar", baz() ].join("");
+        var c5 = [ boo() + bar() + "foo", 1, 2, 3, "bar", bar() + "foo" ].join();
+        var c6 = [ 1, 2, null, undefined, "foo", "bar", baz() ].join();
         var d = [ "foo", 1 + 2 + "bar", "baz" ].join("-");
         var e = [].join(foo + bar);
         var f = [].join("");
@@ -33,10 +42,19 @@ constant_join: {
     expect: {
         var a = "foobarbaz";
         var a1 = "foo,bar,baz";
+        var a2 = "foonullbarnullbaz";
+        var a3 = "foo,bar,baz";
+        var a4 = "foo,,baz";
+        var a5 = "foo,,baz";
+        var a6 = "foo,,baz";
         var b = "foo123bar";
         var c = boo() + "foo123bar" + bar();
         var c1 = "" + boo() + bar() + "foo123bar" + bar();
         var c2 = "12foobar" + baz();
+        var c3 = boo() + bar() + "foo123bar" + (bar() + "foo");
+        var c4 = "12foobar" + baz();
+        var c5 = [ boo() + bar() + "foo", 1, 2, 3, "bar", bar() + "foo" ].join();
+        var c6 = [ "1,2,,,foo,bar", baz() ].join();
         var d = "foo-3bar-baz";
         var e = [].join(foo + bar);
         var f = "";
@@ -73,6 +91,41 @@ constant_join_2: {
     }
 }
 
+constant_join_3: {
+    options = {
+        unsafe: true,
+        evaluate: true,
+    };
+    input: {
+        var a = [ null ].join();
+        var b = [ , ].join();
+        var c = [ , 1, , 3 ].join();
+        var d = [ foo ].join();
+        var e = [ foo, null, undefined, bar ].join("-");
+        var f = [ foo, bar ].join("");
+        var g = [ null, "foo", null, bar + "baz" ].join("");
+        var h = [ null, "foo", null, bar + "baz" ].join("-");
+        var i = [ "foo" + bar, null, baz + "moo" ].join("");
+        var j = [ foo + "bar", baz ].join("");
+        var k = [ foo, "bar" + baz ].join("");
+        var l = [ foo, bar + "baz" ].join("");
+    }
+    expect: {
+        var a = "";
+        var b = "";
+        var c = ",1,,3";
+        var d = "" + foo;
+        var e = [ foo, "-", bar ].join("-");
+        var f = "" + foo + bar;
+        var g = "foo" + (bar + "baz");
+        var h = [ "-foo-", bar + "baz" ].join("-");
+        var i = "foo" + bar + (baz + "moo");
+        var j = foo + "bar" + baz;
+        var k = foo + ("bar" + baz);
+        var l = foo + (bar + "baz");
+    }
+}
+
 for_loop: {
     options = {
         unsafe      : true,