handle comments around parentheses

fixes #2629

lib/parse.js

@@ -1276,9 +1276,16 @@ function parse($TEXT, options) {
               case "(":
                 next();
                 var ex = expression(true);
+                [].push.apply(start.comments_before, ex.start.comments_before);
+                ex.start.comments_before = start.comments_before;
+                start.comments_after = ex.start.comments_after;
                 ex.start = start;
-                ex.end = S.token;
                 expect(")");
+                var end = prev();
+                end.comments_before = ex.end.comments_before;
+                [].push.apply(ex.end.comments_after, end.comments_after);
+                end.comments_after = ex.end.comments_after;
+                ex.end = end;
                 return subscripts(ex, allow_calls);
               case "[":
                 return subscripts(array_(), allow_calls);

test/compress/pure_funcs.js

@@ -293,3 +293,16 @@ unary: {
         bar();
     }
 }
+
+issue_2629: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        /*@__PURE__*/ f1();
+        (/*@__PURE__*/ f2)();
+        /*@__PURE__*/ (f3());
+        (/*@__PURE__*/ f4());
+    }
+    expect: {}
+}

test/mocha/comment.js

@@ -207,4 +207,16 @@ describe("Comment", function() {
         if (result.error) throw result.error;
         assert.strictEqual(result.code, code);
     });
+
+    it("Should preserve comments around IIFE", function() {
+        var result = uglify.minify("/*a*/(/*b*/function(){/*c*/}/*d*/)/*e*/();", {
+            compress: false,
+            mangle: false,
+            output: {
+                comments: "all",
+            },
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, "/*a*/ /*b*/(function(){/*c*/}/*d*/ /*e*/)();");
+    });
 });