5 files changed, 86 insertions, 9 deletions

diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 0c232aa0..f99e0124 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -8164,3 +8164,34 @@ issue_3927: {
     }
     expect_stdout: "PASS"
 }
+
+operator_in: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function log(msg) {
+            console.log(msg);
+        }
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            0 in null;
+            log("FAIL", a);
+        } catch (e) {}
+        log(a);
+    }
+    expect: {
+        function log(msg) {
+            console.log(msg);
+        }
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            0 in null;
+            log("FAIL", a);
+        } catch (e) {}
+        log(a);
+    }
+    expect_stdout: "PASS"
+}
diff --git a/test/compress/pure_funcs.js b/test/compress/pure_funcs.js
index d65399f1..09f0bd45 100644
--- a/test/compress/pure_funcs.js
+++ b/test/compress/pure_funcs.js
@@ -136,7 +136,7 @@ relational: {
         side_effects :true,
     }
     input: {
-        foo() in foo();
+        foo() in new foo();
         foo() instanceof bar();
         foo() < "bar";
         bar() > foo();
diff --git a/test/compress/side_effects.js b/test/compress/side_effects.js
index 63282660..b7ffe47a 100644
--- a/test/compress/side_effects.js
+++ b/test/compress/side_effects.js
@@ -274,3 +274,26 @@ drop_value: {
         foo(), bar();
     }
 }
+
+operator_in: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        try {
+            "foo" in true;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            0 in true;
+            console.log("FAIL");
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}
diff --git a/test/mocha/operator.js b/test/mocha/operator.js
index d36d3a1d..8dfea547 100644
--- a/test/mocha/operator.js
+++ b/test/mocha/operator.js
@@ -486,4 +486,19 @@ describe("operator", function() {
             assert.strictEqual(UglifyJS.parse(exp[0]).print_to_string(), exp[1] + ";");
         });
     });
+    it("Should preserve space between /regex/ and `in`", function() {
+        [
+            "/regex/ in {}",
+            "/regex/g in {}",
+            "0 + /regex/ in {}",
+            "0 + /regex/g in {}",
+        ].forEach(function(exp) {
+            var code = UglifyJS.parse(exp).print_to_string();
+            try {
+                assert.strictEqual(UglifyJS.parse(code).print_to_string(), code);
+            } catch (ex) {
+                assert.fail("Failed to reparse: " + exp + "\n" + ex);
+            }
+        });
+    });
 });
diff --git a/test/ufuzz/index.js b/test/ufuzz/index.js
index edd2ab80..eec4ab4a 100644
--- a/test/ufuzz/index.js
+++ b/test/ufuzz/index.js
@@ -168,7 +168,7 @@ var VALUES = [
     "this",
 ];
 
-var BINARY_OPS_NO_COMMA = [
+var BINARY_OPS = [
     " + ", // spaces needed to disambiguate with ++ cases (could otherwise cause syntax errors)
     " - ",
     "/",
@@ -190,9 +190,14 @@ var BINARY_OPS_NO_COMMA = [
     "%",
     "&&",
     "||",
-    "^" ];
-
-var BINARY_OPS = [","].concat(BINARY_OPS_NO_COMMA);
+    "^",
+    ",",
+];
+BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
+BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
+BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
+BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
+BINARY_OPS.push(" in ");
 
 var ASSIGNMENTS = [
     "=",
@@ -879,7 +884,7 @@ function createNestedBinaryExpr(recurmax, noComma, stmtDepth, canThrow) {
 }
 function _createBinaryExpr(recurmax, noComma, stmtDepth, canThrow) {
     return "(" + _createSimpleBinaryExpr(recurmax, noComma, stmtDepth, canThrow)
-        + createBinaryOp(noComma) + _createSimpleBinaryExpr(recurmax, noComma, stmtDepth, canThrow) + ")";
+        + createBinaryOp(noComma, canThrow) + _createSimpleBinaryExpr(recurmax, noComma, stmtDepth, canThrow) + ")";
 }
 function _createSimpleBinaryExpr(recurmax, noComma, stmtDepth, canThrow) {
     // intentionally generate more hardcore ops
@@ -929,9 +934,12 @@ function createValue() {
     return VALUES[rng(VALUES.length)];
 }
 
-function createBinaryOp(noComma) {
-    if (noComma) return BINARY_OPS_NO_COMMA[rng(BINARY_OPS_NO_COMMA.length)];
-    return BINARY_OPS[rng(BINARY_OPS.length)];
+function createBinaryOp(noComma, canThrow) {
+    var op;
+    do {
+        op = BINARY_OPS[rng(BINARY_OPS.length)];
+    } while (noComma && op == "," || !canThrow && op == " in ");
+    return op;
 }
 
 function createAssignment() {