introduce `merge_vars` (#4100)

1 files changed, 233 insertions, 0 deletions

diff --git a/test/compress/merge_vars.js b/test/compress/merge_vars.js
new file mode 100644
index 00000000..8ef186cf
--- /dev/null
+++ b/test/compress/merge_vars.js
@@ -0,0 +1,233 @@
+merge: {
+    options = {
+        merge_vars: true,
+        toplevel: false,
+    }
+    input: {
+        var a = "foo";
+        console.log(a);
+        function f(b) {
+            var c;
+            console.log(b);
+            c = "bar";
+            console.log(c);
+        }
+        f("baz");
+        var d = "moo";
+        console.log(d);
+    }
+    expect: {
+        var a = "foo";
+        console.log(a);
+        function f(c) {
+            var c;
+            console.log(c);
+            c = "bar";
+            console.log(c);
+        }
+        f("baz");
+        var d = "moo";
+        console.log(d);
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "bar",
+        "moo",
+    ]
+}
+
+merge_toplevel: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "foo";
+        console.log(a);
+        function f(b) {
+            var c;
+            console.log(b);
+            c = "bar";
+            console.log(c);
+        }
+        f("baz");
+        var d = "moo";
+        console.log(d);
+    }
+    expect: {
+        var d = "foo";
+        console.log(d);
+        function f(c) {
+            var c;
+            console.log(c);
+            c = "bar";
+            console.log(c);
+        }
+        f("baz");
+        var d = "moo";
+        console.log(d);
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "bar",
+        "moo",
+    ]
+}
+
+init_scope_vars: {
+    options = {
+        merge_vars: true,
+        unsafe_proto: true,
+    }
+    input: {
+        Function.prototype.call();
+    }
+    expect: {
+        (function() {}).call();
+    }
+    expect_stdout: true
+}
+
+binary_branch: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            a && (c = b);
+            return c || "PASS";
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            a && (c = b);
+            return c || "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+conditional_branch: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            a ? (c = b) : void 0;
+            return c || "PASS";
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            a ? (c = b) : void 0;
+            return c || "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+if_branch: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            if (a) c = b;
+            return c || "PASS";
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            if (a) c = b;
+            return c || "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+switch_branch: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            switch (a) {
+              case 1:
+                c = b;
+                break;
+            }
+            return c || "PASS";
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            var b = "FAIL", c;
+            switch (a) {
+              case 1:
+                c = b;
+                break;
+            }
+            return c || "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+read_before_assign_1: {
+    options = {
+        inline: true,
+        merge_vars: true,
+        sequences: true,
+        toplevel: true,
+    }
+    input: {
+        var c = 0;
+        c = 0;
+        (function() {
+            var a = console.log(++a);
+            a;
+        })();
+        c;
+    }
+    expect: {
+        var c = 0;
+        var a;
+        c = 0,
+        a = console.log(++a);
+    }
+    expect_stdout: "NaN"
+}
+
+read_before_assign_2: {
+    options = {
+        dead_code: true,
+        loops: true,
+        merge_vars: true,
+    }
+    input: {
+        console.log(function(a, a) {
+            while (b)
+                return "FAIL";
+            var b = 1;
+            return "PASS";
+        }(0, []));
+    }
+    expect: {
+        console.log(function(a, a) {
+            if (b)
+                return "FAIL";
+            var b = 1;
+            return "PASS";
+        }(0, []));
+    }
+    expect_stdout: "PASS"
+}