separate keep_classnames & keep_fnames (#2510)

fixes #2418

bin/uglifyjs

@@ -46,6 +46,7 @@ program.option("--config-file <file>", "Read minify() options from JSON file.");
 program.option("-d, --define <expr>[=value]", "Global definitions.", parse_js("define"));
 program.option("--ecma <version>", "Specify ECMAScript release: 5, 6, 7 or 8.");
 program.option("--ie8", "Support non-standard Internet Explorer 8.");
+program.option("--keep-classnames", "Do not mangle/drop class names.");
 program.option("--keep-fnames", "Do not mangle/drop function names. Useful for code relying on Function.prototype.name.");
 program.option("--name-cache <file>", "File to hold mangled name mappings.");
 program.option("--self", "Build UglifyJS as a library (implies --wrap UglifyJS)");
@@ -95,6 +96,9 @@ if (program.define) {
         options.compress.global_defs[expr] = program.define[expr];
     }
 }
+if (program.keepClassnames) {
+    options.keep_classnames = true;
+}
 if (program.keepFnames) {
     options.keep_fnames = true;
 }

lib/compress.js

@@ -69,6 +69,7 @@ function Compressor(options, false_by_default) {
         if_return     : !false_by_default,
         inline        : !false_by_default,
         join_vars     : !false_by_default,
+        keep_classnames: false,
         keep_fargs    : true,
         keep_fnames   : false,
         keep_infinity : false,
@@ -2610,8 +2611,9 @@ merge(Compressor.prototype, {
         // pass 3: we should drop declarations not in_use
         var tt = new TreeTransformer(
             function before(node, descend, in_list) {
-                if (!compressor.option("keep_fnames")
+                if (node.name
-                    && node.name && (node instanceof AST_Function || node instanceof AST_ClassExpression)) {
+                    && (!compressor.option("keep_classnames") && node instanceof AST_ClassExpression
+                        || !compressor.option("keep_fnames") && node instanceof AST_Function)) {
                     var def = node.name.definition();
                     // any declarations with same name will overshadow
                     // name of this anonymous function and can therefore

lib/minify.js

@@ -51,6 +51,7 @@ function minify(files, options) {
             compress: {},
             ecma: undefined,
             ie8: false,
+            keep_classnames: undefined,
             keep_fnames: false,
             mangle: {},
             nameCache: null,
@@ -65,8 +66,12 @@ function minify(files, options) {
         var timings = options.timings && {
             start: Date.now()
         };
+        if (options.keep_classnames === undefined) {
+            options.keep_classnames = options.keep_fnames;
+        }
         set_shorthand("ecma", options, [ "parse", "compress", "output" ]);
         set_shorthand("ie8", options, [ "compress", "mangle", "output" ]);
+        set_shorthand("keep_classnames", options, [ "compress", "mangle" ]);
         set_shorthand("keep_fnames", options, [ "compress", "mangle" ]);
         set_shorthand("toplevel", options, [ "compress", "mangle" ]);
         set_shorthand("warnings", options, [ "compress" ]);

test/compress/drop-unused.js

@@ -1574,3 +1574,101 @@ issue_2288: {
         }
     }
 }
+
+issue_2418_1: {
+    options = {
+        unused: true,
+    }
+    input: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+    expect: {
+        class C {}
+        function F() {}
+        (class {});
+        (function() {});
+    }
+}
+
+issue_2418_2: {
+    options = {
+        keep_classnames: false,
+        keep_fnames: false,
+        unused: true,
+    }
+    input: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+    expect: {
+        class C {}
+        function F() {}
+        (class {});
+        (function() {});
+    }
+}
+
+issue_2418_3: {
+    options = {
+        keep_classnames: false,
+        keep_fnames: true,
+        unused: true,
+    }
+    input: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+    expect: {
+        class C {}
+        function F() {}
+        (class {});
+        (function f() {});
+    }
+}
+
+issue_2418_4: {
+    options = {
+        keep_classnames: true,
+        keep_fnames: false,
+        unused: true,
+    }
+    input: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+    expect: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function() {});
+    }
+}
+
+issue_2418_5: {
+    options = {
+        keep_classnames: true,
+        keep_fnames: true,
+        unused: true,
+    }
+    input: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+    expect: {
+        class C {}
+        function F() {}
+        (class c {});
+        (function f() {});
+    }
+}

test/compress/hoist_props.js

@@ -389,6 +389,7 @@ hoist_class: {
         evaluate: true,
         hoist_props: true,
         inline: true,
+        keep_classnames: true,
         keep_fnames: true,
         passes: 2,
         reduce_funcs: true,
@@ -432,6 +433,7 @@ hoist_class_with_new: {
         evaluate: true,
         hoist_props: true,
         inline: true,
+        keep_classnames: true,
         keep_fnames: true,
         passes: 2,
         reduce_funcs: true,