drop argument value after collapse_vars (#2190)

lib/compress.js

@@ -902,6 +902,14 @@ merge(Compressor.prototype, {
             }
 
             function remove_candidate(expr) {
+                if (expr.name instanceof AST_SymbolFunarg) {
+                    var index = compressor.self().argnames.indexOf(expr.name);
+                    var args = compressor.parent().args;
+                    if (args[index]) args[index] = make_node(AST_Number, args[index], {
+                        value: 0
+                    });
+                    return true;
+                }
                 var found = false;
                 return statements[stat_index].transform(new TreeTransformer(function(node, descend, in_list) {
                     if (found) return node;
@@ -3205,7 +3213,7 @@ merge(Compressor.prototype, {
             var value = stat.value;
             if (!value || value.is_constant_expression()) {
                 var args = self.args.concat(value || make_node(AST_Undefined, self));
-                return make_sequence(self, args).transform(compressor);
+                return make_sequence(self, args).optimize(compressor);
             }
         }
         if (exp instanceof AST_Function) {
@@ -3246,12 +3254,12 @@ merge(Compressor.prototype, {
                 }
                 if (value) {
                     var args = self.args.concat(value);
-                    return make_sequence(self, args).transform(compressor);
+                    return make_sequence(self, args).optimize(compressor);
                 }
             }
             if (compressor.option("side_effects") && all(exp.body, is_empty)) {
                 var args = self.args.concat(make_node(AST_Undefined, self));
-                return make_sequence(self, args).transform(compressor);
+                return make_sequence(self, args).optimize(compressor);
             }
         }
         if (compressor.option("drop_console")) {

test/compress/collapse_vars.js

@@ -2187,7 +2187,7 @@ compound_assignment: {
     expect_stdout: "4"
 }
 
-issue_2187: {
+issue_2187_1: {
     options = {
         collapse_vars: true,
         unused: true,
@@ -2217,3 +2217,42 @@ issue_2187: {
         "2",
     ]
 }
+
+issue_2187_2: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var b = 1;
+        console.log(function(a) {
+            return a && ++b;
+        }(b--));
+    }
+    expect: {
+        var b = 1;
+        console.log(function(a) {
+            return b-- && ++b;
+        }());
+    }
+    expect_stdout: "1"
+}
+
+issue_2187_3: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        unused: true,
+    }
+    input: {
+        var b = 1;
+        console.log(function(a) {
+            return a && ++b;
+        }(b--));
+    }
+    expect: {
+        var b = 1;
+        console.log(b-- && ++b);
+    }
+    expect_stdout: "1"
+}

test/compress/drop-unused.js

@@ -1113,7 +1113,7 @@ issue_2105: {
     options = {
         collapse_vars: true,
         inline: true,
-        passes: 2,
+        passes: 3,
         reduce_vars: true,
         side_effects: true,
         unused: true,