Never produce -0 when evaluating expressions (like -"")

Fix for #1085. The major case was already there, but more expressions can result in -0.

2 files changed, 12 insertions, 3 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 6436796f..e8c42c04 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1029,9 +1029,9 @@ merge(Compressor.prototype, {
               case "void": return void ev(e, compressor);
               case "~": return ~ev(e, compressor);
               case "-":
-                e = ev(e, compressor);
-                if (e === 0) throw def;
-                return -e;
+                e = -ev(e, compressor);
+                if (e === -0) throw def;
+                return e;
               case "+": return +ev(e, compressor);
             }
             throw def;
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
new file mode 100644
index 00000000..9aa6b3d3
--- /dev/null
+++ b/test/compress/evaluate.js
@@ -0,0 +1,9 @@
+negative_zero: {
+    options = { evaluate: true }
+    input: {
+        assert.sameValue(-"", -0, '-""');
+    }
+    expect: {
+        assert.sameValue(-"", -0, '-""');
+    }
+}