fix corner case in `evaluate` (#4143)

fixes #4142

diff --git a/lib/compress.js b/lib/compress.js
index cf46e47..f66b718 100644 (file)
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -7767,12 +7767,11 @@ merge(Compressor.prototype, {
                 associative = compressor.option("unsafe_math");
                 // +a - b => a - b
                 // a - +b => a - b
-                [ "left", "right" ].forEach(function(operand) {
+                if (self.operator != "+") [ "left", "right" ].forEach(function(operand) {
                     var node = self[operand];
                     if (node instanceof AST_UnaryPrefix && node.operator == "+") {
                         var exp = node.expression;
-                        if (exp.is_boolean(compressor) || exp.is_number(compressor)
-                            || self.operator != "+" && exp.is_string(compressor)) {
+                        if (exp.is_boolean(compressor) || exp.is_number(compressor) || exp.is_string(compressor)) {
                             self[operand] = exp;
                         }
                     }

diff --git a/test/compress/numbers.js b/test/compress/numbers.js
index 7f355a1..c7aab68 100644 (file)
--- a/test/compress/numbers.js
+++ b/test/compress/numbers.js
@@ -1322,3 +1322,16 @@ issue_4137: {
     }
     expect_stdout: "0"
 }
+
+issue_4142: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        console.log("" + +(0 === console));
+    }
+    expect: {
+        console.log("" + +(0 === console));
+    }
+    expect_stdout: "0"
+}