support spread syntax (#4328)

3 files changed, 431 insertions, 16 deletions

diff --git a/test/compress/spread.js b/test/compress/spread.js
new file mode 100644
index 00000000..b7a6f753
--- /dev/null
+++ b/test/compress/spread.js
@@ -0,0 +1,371 @@
+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        [ ...a = "PASS", "PASS"].slice();
+        console.log(a);
+    }
+    expect: {
+        var a;
+        [ ...a = "PASS", "PASS"].slice();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            [ ...42, "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            [ ...42, "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            [ ...(a = "PASS", 42), "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            [ ...(a = "PASS", 42), "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_4: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+dont_inline: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+do_inline: {
+    options = {
+        properties: true,
+        inline: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(("FAIL", "PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_empty_call_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        try {
+            (function() {})(...null);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            [ ...null ];
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_empty_call_2: {
+    options = {
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        (function() {})(...[ console.log("PASS") ]);
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+convert_hole: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log(...[ "PASS", , 42 ]);
+    }
+    expect: {
+        console.log("PASS", void 0, 42);
+    }
+    expect_stdout: "PASS undefined 42"
+    node_version: ">=6"
+}
+
+keep_property_access: {
+    options = {
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(function() {
+            return [ ..."foo" ][0];
+        }());
+    }
+    expect: {
+        console.log(function() {
+            return [ ..."foo" ][0];
+        }());
+    }
+    expect_stdout: "f"
+    node_version: ">=6"
+}
+
+keep_fargs: {
+    options = {
+        keep_fargs: "strict",
+        unused: true,
+    }
+    input: {
+        var a = [ "PASS" ];
+        (function(b, c) {
+            console.log(c);
+        })(console, ...a);
+    }
+    expect: {
+        var a = [ "PASS" ];
+        (function(b, c) {
+            console.log(c);
+        })(console, ...a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+reduce_vars_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+reduce_vars_2: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_object: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({ ...console.log("PASS") });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_getter: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            ...{
+                get p() {
+                    console.log("PASS");
+                },
+            },
+            get q() {
+                console.log("FAIL");
+            },
+        });
+    }
+    expect: {
+        ({
+            ...{
+                get p() {
+                    console.log("PASS");
+                },
+            },
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_accessor: {
+    options = {
+        properties: true,
+    }
+    input: {
+        var o = {
+            ...{
+                get p() {
+                    console.log("GET");
+                    return this.r;
+                },
+                set q(v) {
+                    console.log("SET", v);
+                },
+                r: 42,
+            },
+            r: null,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            ...{
+                get p() {
+                    console.log("GET");
+                    return this.r;
+                },
+                set q(v) {
+                    console.log("SET", v);
+                },
+                r: 42,
+            },
+            r: null,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "GET",
+        "p 42",
+        "q undefined",
+        "r null",
+    ]
+    node_version: ">=8"
+}
+
+unused_var_side_effects: {
+    options = {
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            var b = {
+                ...a,
+            };
+        })({
+            get p() {
+                console.log("PASS");
+            },
+        });
+    }
+    expect: {
+        (function(a) {
+            ({
+                ...a,
+            });
+        })({
+            get p() {
+                console.log("PASS");
+            },
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
diff --git a/test/reduce.js b/test/reduce.js
index 2b1b42e7..cda79f8a 100644
--- a/test/reduce.js
+++ b/test/reduce.js
@@ -135,7 +135,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 if (expr && !(expr instanceof U.AST_Hole)) {
                     node.start._permute++;
                     CHANGED = true;
-                    return expr;
+                    return expr instanceof U.AST_Spread ? expr.expression : expr;
                 }
             }
             else if (node instanceof U.AST_Binary) {
@@ -164,7 +164,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 ][ ((node.start._permute += step) * steps | 0) % 3 ];
                 if (expr) {
                     CHANGED = true;
-                    return expr;
+                    return expr instanceof U.AST_Spread ? expr.expression : expr;
                 }
                 if (node.expression instanceof U.AST_Function) {
                     // hoist and return expressions from the IIFE function expression
@@ -381,9 +381,8 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             }
 
             if (in_list) {
-                // special case to drop object properties and switch branches
-                if (parent instanceof U.AST_Object
-                    || parent instanceof U.AST_Switch && parent.expression != node) {
+                // drop switch branches
+                if (parent instanceof U.AST_Switch && parent.expression != node) {
                     node.start._permute++;
                     CHANGED = true;
                     return List.skip;
@@ -404,7 +403,9 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 }
 
                 // skip element/property from (destructured) array/object
-                if (parent instanceof U.AST_Array || parent instanceof U.AST_Destructured || parent instanceof AST_Object) {
+                if (parent instanceof U.AST_Array
+                    || parent instanceof U.AST_Destructured
+                    || parent instanceof U.AST_Object) {
                     node.start._permute++;
                     CHANGED = true;
                     return List.skip;
diff --git a/test/ufuzz/index.js b/test/ufuzz/index.js
index 0e56bb1d..7c76b348 100644
--- a/test/ufuzz/index.js
+++ b/test/ufuzz/index.js
@@ -371,9 +371,24 @@ function createParams(noDuplicate) {
 }
 
 function createArgs(recurmax, stmtDepth, canThrow) {
+    recurmax--;
     var args = [];
-    for (var n = rng(4); --n >= 0;) {
-        args.push(rng(2) ? createValue() : createExpression(recurmax - 1, COMMA_OK, stmtDepth, canThrow));
+    for (var n = rng(4); --n >= 0;) switch (rng(50)) {
+      case 0:
+      case 1:
+        var name = getVarName();
+        if (canThrow && rng(8) === 0) {
+            args.push("..." + name);
+        } else {
+            args.push('...("" + ' + name + ")");
+        }
+        break;
+      case 2:
+        args.push("..." + createArrayLiteral(recurmax, stmtDepth, canThrow));
+        break;
+      default:
+        args.push(rng(2) ? createValue() : createExpression(recurmax, COMMA_OK, stmtDepth, canThrow));
+        break;
     }
     return args.join(", ");
 }
@@ -1044,13 +1059,30 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
 
 function createArrayLiteral(recurmax, stmtDepth, canThrow) {
     recurmax--;
-    var arr = "[";
-    for (var i = rng(6); --i >= 0;) {
+    var arr = [];
+    for (var i = rng(6); --i >= 0;) switch (rng(50)) {
+      case 0:
+      case 1:
         // in rare cases produce an array hole element
-        var element = rng(20) ? createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) : "";
-        arr += element + ", ";
+        arr.push("");
+        break;
+      case 2:
+      case 3:
+        var name = getVarName();
+        if (canThrow && rng(8) === 0) {
+            arr.push("..." + name);
+        } else {
+            arr.push('...("" + ' + name + ")");
+        }
+        break;
+      case 4:
+        arr.push("..." + createArrayLiteral(recurmax, stmtDepth, canThrow));
+        break;
+      default:
+        arr.push(createExpression(recurmax, COMMA_OK, stmtDepth, canThrow));
+        break;
     }
-    return arr + "]";
+    return "[" + arr.join(", ") + "]";
 }
 
 var SAFE_KEYS = [
@@ -1135,13 +1167,20 @@ function createObjectFunction(recurmax, stmtDepth, canThrow) {
 function createObjectLiteral(recurmax, stmtDepth, canThrow) {
     recurmax--;
     var obj = ["({"];
-    for (var i = rng(6); --i >= 0;) switch (rng(30)) {
+    for (var i = rng(6); --i >= 0;) switch (rng(50)) {
       case 0:
-        obj.push(createObjectFunction(recurmax, stmtDepth, canThrow));
-        break;
       case 1:
         obj.push(getVarName() + ",");
         break;
+      case 2:
+        obj.push(createObjectFunction(recurmax, stmtDepth, canThrow));
+        break;
+      case 3:
+        obj.push("..." + getVarName() + ",");
+        break;
+      case 4:
+        obj.push("..." + createObjectLiteral(recurmax, stmtDepth, canThrow) + ",");
+        break;
       default:
         obj.push(createObjectKey(recurmax, stmtDepth, canThrow) + ":(" + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "),");
         break;
@@ -1591,6 +1630,9 @@ function patch_try_catch(orig, toplevel) {
             } else if (result.name == "TypeError" && /'in'/.test(result.message)) {
                 index = result.ufuzz_catch;
                 return orig.slice(0, index) + result.ufuzz_var + ' = new Error("invalid `in`");' + orig.slice(index);
+            } else if (result.name == "TypeError" && /not iterable/.test(result.message)) {
+                index = result.ufuzz_catch;
+                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("spread not iterable");' + orig.slice(index);
             } else if (result.name == "RangeError" && result.message == "Maximum call stack size exceeded") {
                 index = result.ufuzz_try;
                 return orig.slice(0, index) + 'throw new Error("skipping infinite recursion");' + orig.slice(index);
@@ -1656,6 +1698,7 @@ for (var round = 1; round <= num_iterations; round++) {
                 ok = sandbox.same_stdout(orig_result[toplevel ? 3 : 2], uglify_result);
             }
             // ignore difference in error message caused by `in`
+            // ignore difference in error message caused by spread syntax
             // ignore difference in depth of termination caused by infinite recursion
             if (!ok) {
                 var orig_skipped = patch_try_catch(original_code, toplevel);