fix comments output & improve /*@__PURE__*/

- fix whitespace around comments
- fix comment parsing around parentheses
- consider parentheses when parsing `/*@__PURE__*/`
- remove all `/*@__PURE__*/` on output

fixes #2638

lib/compress.js

@@ -2292,29 +2292,13 @@ merge(Compressor.prototype, {
         });
     });
 
-    AST_Call.DEFMETHOD("has_pure_annotation", function(compressor) {
-        if (!compressor.option("side_effects")) return false;
-        if (this.pure !== undefined) return this.pure;
-        var pure = false;
-        var comments, pure_comment;
-        if (this.start
-            && (comments = this.start.comments_before)
-            && comments.length
-            && (pure_comment = find_if(function (comment) {
-                return /[@#]__PURE__/.test(comment.value);
-            }, comments))) {
-            pure = pure_comment;
-        }
-        return this.pure = pure;
-    });
-
     var global_pure_fns = makePredicate("Boolean decodeURI decodeURIComponent Date encodeURI encodeURIComponent Error escape EvalError isFinite isNaN Number Object parseFloat parseInt RangeError ReferenceError String SyntaxError TypeError unescape URIError");
     AST_Call.DEFMETHOD("is_expr_pure", function(compressor) {
         if (compressor.option("unsafe")) {
             var expr = this.expression;
             if (is_undeclared_ref(expr) && global_pure_fns(expr.name)) return true;
         }
-        return this.has_pure_annotation(compressor) || !compressor.pure_funcs(this);
+        return this.pure || !compressor.pure_funcs(this);
     });
 
     // determine if expression has side effects
@@ -3164,7 +3148,6 @@ merge(Compressor.prototype, {
             }
             if (this.pure) {
                 compressor.warn("Dropping __PURE__ call [{file}:{line},{col}]", this.start);
-                this.pure.value = this.pure.value.replace(/[@#]__PURE__/g, ' ');
             }
             var args = trim(this.args, compressor, first_in_statement);
             return args && make_sequence(this, args);
@@ -3961,7 +3944,7 @@ merge(Compressor.prototype, {
                         && (def = exp.definition()).references.length == 1
                         && !recursive_ref(compressor, def)
                         && fn.is_constant_expression(exp.scope))
-                && !self.has_pure_annotation(compressor)
+                && !self.pure
                 && !fn.contains_this()
                 && (scope = can_flatten_args(fn))
                 && (value = flatten_body(stat))) {

lib/output.js

@@ -201,6 +201,8 @@ function OutputStream(options) {
     var might_need_semicolon = false;
     var might_add_newline = 0;
     var need_newline_indented = false;
+    var need_space = false;
+    var newline_insert = -1;
     var last = "";
     var mapping_token, mapping_name, mappings = options.source_map && [];
 
@@ -266,6 +268,13 @@ function OutputStream(options) {
                 indent();
             }
         }
+        if (need_space && ch) {
+            need_space = false;
+            if (!/[\s;})]/.test(ch)) {
+                space();
+            }
+        }
+        newline_insert = -1;
         var prev = last.charAt(last.length - 1);
         if (might_need_semicolon) {
             might_need_semicolon = false;
@@ -364,7 +373,13 @@ function OutputStream(options) {
     } : function(col, cont) { return cont() };
 
     var newline = options.beautify ? function() {
-        print("\n");
+        if (newline_insert < 0) return print("\n");
+        if (OUTPUT[newline_insert] != "\n") {
+            OUTPUT = OUTPUT.slice(0, newline_insert) + "\n" + OUTPUT.slice(newline_insert);
+            current_pos++;
+            current_line++;
+        }
+        newline_insert++;
     } : options.max_line_len ? function() {
         ensure_line_len();
         might_add_newline = OUTPUT.length;
@@ -495,11 +510,11 @@ function OutputStream(options) {
                     }
                 }
                 if (/comment[134]/.test(c.type)) {
-                    print("//" + c.value + "\n");
+                    print("//" + c.value.replace(/[@#]__PURE__/g, ' ') + "\n");
                     indent();
                     last_nlb = true;
                 } else if (c.type == "comment2") {
-                    print("/*" + c.value + "*/");
+                    print("/*" + c.value.replace(/[@#]__PURE__/g, ' ') + "*/");
                     last_nlb = false;
                 }
             });
@@ -521,21 +536,28 @@ function OutputStream(options) {
         var comments = token[tail ? "comments_before" : "comments_after"];
         if (comments && comments._dumped !== self) {
             comments._dumped = self;
+            var insert = OUTPUT.length;
             comments.filter(comment_filter, node).forEach(function(c, i) {
-                if (need_newline_indented || c.nlb) {
+                need_space = false;
+                if (need_newline_indented) {
                     print("\n");
                     indent();
                     need_newline_indented = false;
+                } else if (c.nlb && (i > 0 || !/(^|\n) *$/.test(OUTPUT))) {
+                    print("\n");
+                    indent();
                 } else if (i > 0 || !tail) {
                     space();
                 }
                 if (/comment[134]/.test(c.type)) {
-                    print("//" + c.value);
+                    print("//" + c.value.replace(/[@#]__PURE__/g, ' '));
                     need_newline_indented = true;
                 } else if (c.type == "comment2") {
-                    print("/*" + c.value + "*/");
+                    print("/*" + c.value.replace(/[@#]__PURE__/g, ' ') + "*/");
+                    need_space = true;
                 }
             });
+            if (OUTPUT.length > insert) newline_insert = insert;
         }
     }
 

lib/parse.js

@@ -1276,8 +1276,17 @@ function parse($TEXT, options) {
               case "(":
                 next();
                 var ex = expression(true);
-                [].push.apply(start.comments_before, ex.start.comments_before);
+                var len = start.comments_before.length;
-                ex.start.comments_before = start.comments_before;
+                [].unshift.apply(ex.start.comments_before, start.comments_before);
+                start.comments_before = ex.start.comments_before;
+                start.comments_before_length = len;
+                if (len == 0 && start.comments_before.length > 0) {
+                    var comment = start.comments_before[0];
+                    if (!comment.nlb) {
+                        comment.nlb = start.nlb;
+                        start.nlb = false;
+                    }
+                }
                 start.comments_after = ex.start.comments_after;
                 ex.start = start;
                 expect(")");
@@ -1286,6 +1295,7 @@ function parse($TEXT, options) {
                 [].push.apply(ex.end.comments_after, end.comments_after);
                 end.comments_after = ex.end.comments_after;
                 ex.end = end;
+                if (ex instanceof AST_Call) mark_pure(ex);
                 return subscripts(ex, allow_calls);
               case "[":
                 return subscripts(array_(), allow_calls);
@@ -1433,6 +1443,19 @@ function parse($TEXT, options) {
         return sym;
     };
 
+    function mark_pure(call) {
+        var start = call.start;
+        var comments = start.comments_before;
+        var i = HOP(start, "comments_before_length") ? start.comments_before_length : comments.length;
+        while (--i >= 0) {
+            var comment = comments[i];
+            if (/[@#]__PURE__/.test(comment.value)) {
+                call.pure = comment;
+                break;
+            }
+        }
+    }
+
     var subscripts = function(expr, allow_calls) {
         var start = expr.start;
         if (is("punc", ".")) {
@@ -1457,12 +1480,14 @@ function parse($TEXT, options) {
         }
         if (allow_calls && is("punc", "(")) {
             next();
-            return subscripts(new AST_Call({
+            var call = new AST_Call({
                 start      : start,
                 expression : expr,
                 args       : expr_list(")"),
                 end        : prev()
-            }), true);
+            });
+            mark_pure(call);
+            return subscripts(call, true);
         }
         return expr;
     };

test/compress/pure_funcs.js

@@ -298,19 +298,27 @@ issue_2629_1: {
     options = {
         side_effects: true,
     }
+    beautify = {
+        comments: "all",
+    }
     input: {
         /*@__PURE__*/ a();
         /*@__PURE__*/ (b());
         (/*@__PURE__*/ c)();
         (/*@__PURE__*/ d());
     }
-    expect: {}
+    expect_exact: [
+        "/* */c();",
+    ]
 }
 
 issue_2629_2: {
     options = {
         side_effects: true,
     }
+    beautify = {
+        comments: "all",
+    }
     input: {
         /*@__PURE__*/ a(1)(2)(3);
         /*@__PURE__*/ (b(1))(2)(3);
@@ -321,30 +329,44 @@ issue_2629_2: {
         (/*@__PURE__*/ g(1)(2))(3);
         (/*@__PURE__*/ h(1)(2)(3));
     }
-    expect: {}
+    expect_exact: [
+        "/* */e(1)(2)(3);",
+        "/* */f(1)(2)(3);",
+        "/* */g(1)(2)(3);",
+    ]
 }
 
 issue_2629_3: {
     options = {
         side_effects: true,
     }
+    beautify = {
+        comments: "all",
+    }
     input: {
         /*@__PURE__*/ a.x(1).y(2).z(3);
-        /*@__PURE__*/ (a.x)(1).y(2).z(3);
+        /*@__PURE__*/ (b.x)(1).y(2).z(3);
-        /*@__PURE__*/ (a.x(1)).y(2).z(3);
+        /*@__PURE__*/ (c.x(1)).y(2).z(3);
-        /*@__PURE__*/ (a.x(1).y)(2).z(3);
+        /*@__PURE__*/ (d.x(1).y)(2).z(3);
-        /*@__PURE__*/ (a.x(1).y(2)).z(3);
+        /*@__PURE__*/ (e.x(1).y(2)).z(3);
-        /*@__PURE__*/ (a.x(1).y(2).z)(3);
+        /*@__PURE__*/ (f.x(1).y(2).z)(3);
-        /*@__PURE__*/ (a.x(1).y(2).z(3));
+        /*@__PURE__*/ (g.x(1).y(2).z(3));
-        (/*@__PURE__*/ a).x(1).y(2).z(3);
+        (/*@__PURE__*/ h).x(1).y(2).z(3);
-        (/*@__PURE__*/ a.x)(1).y(2).z(3);
+        (/*@__PURE__*/ i.x)(1).y(2).z(3);
-        (/*@__PURE__*/ a.x(1)).y(2).z(3);
+        (/*@__PURE__*/ j.x(1)).y(2).z(3);
-        (/*@__PURE__*/ a.x(1).y)(2).z(3);
+        (/*@__PURE__*/ k.x(1).y)(2).z(3);
-        (/*@__PURE__*/ a.x(1).y(2)).z(3);
+        (/*@__PURE__*/ l.x(1).y(2)).z(3);
-        (/*@__PURE__*/ a.x(1).y(2).z)(3);
+        (/*@__PURE__*/ m.x(1).y(2).z)(3);
-        (/*@__PURE__*/ a.x(1).y(2).z(3));
+        (/*@__PURE__*/ n.x(1).y(2).z(3));
     }
-    expect: {}
+    expect_exact: [
+        "/* */h.x(1).y(2).z(3);",
+        "/* */i.x(1).y(2).z(3);",
+        "/* */j.x(1).y(2).z(3);",
+        "/* */k.x(1).y(2).z(3);",
+        "/* */l.x(1).y(2).z(3);",
+        "/* */m.x(1).y(2).z(3);",
+    ]
 }
 
 issue_2629_4: {
@@ -375,3 +397,20 @@ issue_2629_5: {
         w(), y();
     }
 }
+
+issue_2638: {
+    options = {
+        side_effects: true,
+    }
+    beautify = {
+        comments: "all",
+    }
+    input: {
+        /*@__PURE__*/(g() || h())(x(), y());
+        (/*@__PURE__*/ (a() || b()))(c(), d());
+    }
+    expect_exact: [
+        "/* */x(),y();",
+        "/* */(a()||b())(c(),d());",
+    ]
+}

test/mocha/minify.js

@@ -247,7 +247,7 @@ describe("minify", function() {
             var code = result.code;
             assert.strictEqual(code, "//  comment1   comment2\nbar();");
         });
-        it("should not drop #__PURE__ hint if function is retained", function() {
+        it("should drop #__PURE__ hint if function is retained", function() {
             var result = Uglify.minify("var a = /*#__PURE__*/(function(){ foo(); })();", {
                 output: {
                     comments: "all",
@@ -255,7 +255,7 @@ describe("minify", function() {
                 }
             });
             var code = result.code;
-            assert.strictEqual(code, "var a=/*#__PURE__*/function(){foo()}();");
+            assert.strictEqual(code, "var a=/* */function(){foo()}();");
         })
     });