improve error messages (#1506)

- better inheritance of `Error` sub-classes
- mark parse error against source in CLI

closes #235
closes #348
closes #524
closes #1356
closes #1405

15 files changed, 133 insertions, 48 deletions

diff --git a/bin/uglifyjs b/bin/uglifyjs
index d0c3abb2..367d66e2 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -364,7 +364,21 @@ async.eachLimit(files, 1, function (file, cb) {
                 } catch(ex) {
                     if (ex instanceof UglifyJS.JS_Parse_Error) {
                         print_error("Parse error at " + file + ":" + ex.line + "," + ex.col);
-                        print_error(ex.message);
+                        var col = ex.col;
+                        var line = code.split(/\r?\n/)[ex.line - (col ? 1 : 2)];
+                        if (line) {
+                            if (col > 40) {
+                                line = line.slice(col - 40);
+                                col = 40;
+                            }
+                            if (col) {
+                                print_error(line.slice(0, 80));
+                                print_error(line.slice(0, col).replace(/\S/g, " ") + "^");
+                            } else {
+                                print_error(line.slice(-40));
+                                print_error(line.slice(-40).replace(/\S/g, " ") + "^");
+                            }
+                        }
                         print_error(ex.stack);
                         process.exit(1);
                     }
@@ -390,7 +404,7 @@ async.eachLimit(files, 1, function (file, cb) {
         var compressor = COMPRESS && UglifyJS.Compressor(COMPRESS);
     } catch(ex) {
         if (ex instanceof UglifyJS.DefaultsError) {
-            print_error(ex.msg);
+            print_error(ex.message);
             print_error("Supported options:");
             print_error(sys.inspect(ex.defs));
             process.exit(1);
diff --git a/lib/parse.js b/lib/parse.js
index 37f06df7..9b198ccd 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -195,12 +195,11 @@ function JS_Parse_Error(message, filename, line, col, pos) {
     this.line = line;
     this.col = col;
     this.pos = pos;
-    this.stack = new Error().stack;
-};
-
-JS_Parse_Error.prototype.toString = function() {
-    return this.message + " (line: " + this.line + ", col: " + this.col + ", pos: " + this.pos + ")" + "\n\n" + this.stack;
 };
+JS_Parse_Error.prototype = Object.create(Error.prototype);
+JS_Parse_Error.prototype.constructor = JS_Parse_Error;
+JS_Parse_Error.prototype.name = "SyntaxError";
+configure_error_stack(JS_Parse_Error);
 
 function js_error(message, filename, line, col, pos) {
     throw new JS_Parse_Error(message, filename, line, col, pos);
@@ -350,13 +349,13 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         });
         if (prefix) num = prefix + num;
         if (RE_OCT_NUMBER.test(num) && next_token.has_directive("use strict")) {
-            parse_error("SyntaxError: Legacy octal literals are not allowed in strict mode");
+            parse_error("Legacy octal literals are not allowed in strict mode");
         }
         var valid = parse_js_number(num);
         if (!isNaN(valid)) {
             return token("num", valid);
         } else {
-            parse_error("SyntaxError: Invalid syntax: " + num);
+            parse_error("Invalid syntax: " + num);
         }
     };
 
@@ -395,7 +394,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         // Parse
         if (ch === "0") return "\0";
         if (ch.length > 0 && next_token.has_directive("use strict"))
-            parse_error("SyntaxError: Legacy octal escape sequences are not allowed in strict mode");
+            parse_error("Legacy octal escape sequences are not allowed in strict mode");
         return String.fromCharCode(parseInt(ch, 8));
     }
 
@@ -404,18 +403,18 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         for (; n > 0; --n) {
             var digit = parseInt(next(true), 16);
             if (isNaN(digit))
-                parse_error("SyntaxError: Invalid hex-character pattern in string");
+                parse_error("Invalid hex-character pattern in string");
             num = (num << 4) | digit;
         }
         return num;
     };
 
-    var read_string = with_eof_error("SyntaxError: Unterminated string constant", function(quote_char){
+    var read_string = with_eof_error("Unterminated string constant", function(quote_char){
         var quote = next(), ret = "";
         for (;;) {
             var ch = next(true, true);
             if (ch == "\\") ch = read_escaped_char(true);
-            else if (NEWLINE_CHARS(ch)) parse_error("SyntaxError: Unterminated string constant");
+            else if (NEWLINE_CHARS(ch)) parse_error("Unterminated string constant");
             else if (ch == quote) break;
             ret += ch;
         }
@@ -440,7 +439,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         return next_token;
     };
 
-    var skip_multiline_comment = with_eof_error("SyntaxError: Unterminated multiline comment", function(){
+    var skip_multiline_comment = with_eof_error("Unterminated multiline comment", function(){
         var regex_allowed = S.regex_allowed;
         var i = find("*/", true);
         var text = S.text.substring(S.pos, i).replace(/\r\n|\r|\u2028|\u2029/g, '\n');
@@ -460,9 +459,9 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
                 else break;
             }
             else {
-                if (ch != "u") parse_error("SyntaxError: Expecting UnicodeEscapeSequence -- uXXXX");
+                if (ch != "u") parse_error("Expecting UnicodeEscapeSequence -- uXXXX");
                 ch = read_escaped_char();
-                if (!is_identifier_char(ch)) parse_error("SyntaxError: Unicode char: " + ch.charCodeAt(0) + " is not valid in identifier");
+                if (!is_identifier_char(ch)) parse_error("Unicode char: " + ch.charCodeAt(0) + " is not valid in identifier");
                 name += ch;
                 backslash = false;
             }
@@ -474,10 +473,10 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         return name;
     };
 
-    var read_regexp = with_eof_error("SyntaxError: Unterminated regular expression", function(regexp){
+    var read_regexp = with_eof_error("Unterminated regular expression", function(regexp){
         var prev_backslash = false, ch, in_class = false;
         while ((ch = next(true))) if (NEWLINE_CHARS(ch)) {
-            parse_error("SyntaxError: Unexpected line terminator");
+            parse_error("Unexpected line terminator");
         } else if (prev_backslash) {
             regexp += "\\" + ch;
             prev_backslash = false;
@@ -498,7 +497,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         try {
           return token("regexp", new RegExp(regexp, mods));
         } catch(e) {
-          parse_error("SyntaxError: " + e.message);
+          parse_error(e.message);
         }
     });
 
@@ -599,7 +598,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             }
             break;
         }
-        parse_error("SyntaxError: Unexpected character '" + ch + "'");
+        parse_error("Unexpected character '" + ch + "'");
     };
 
     next_token.context = function(nc) {
@@ -756,14 +755,14 @@ function parse($TEXT, options) {
     function unexpected(token) {
         if (token == null)
             token = S.token;
-        token_error(token, "SyntaxError: Unexpected token: " + token.type + " (" + token.value + ")");
+        token_error(token, "Unexpected token: " + token.type + " (" + token.value + ")");
     };
 
     function expect_token(type, val) {
         if (is(type, val)) {
             return next();
         }
-        token_error(S.token, "SyntaxError: Unexpected token " + S.token.type + " «" + S.token.value + "»" + ", expected " + type + " «" + val + "»");
+        token_error(S.token, "Unexpected token " + S.token.type + " «" + S.token.value + "»" + ", expected " + type + " «" + val + "»");
     };
 
     function expect(punc) { return expect_token("punc", punc); };
@@ -892,7 +891,7 @@ function parse($TEXT, options) {
 
               case "return":
                 if (S.in_function == 0 && !options.bare_returns)
-                    croak("SyntaxError: 'return' outside of function");
+                    croak("'return' outside of function");
                 return new AST_Return({
                     value: ( is("punc", ";")
                              ? (next(), null)
@@ -909,7 +908,7 @@ function parse($TEXT, options) {
 
               case "throw":
                 if (S.token.nlb)
-                    croak("SyntaxError: Illegal newline after 'throw'");
+                    croak("Illegal newline after 'throw'");
                 return new AST_Throw({
                     value: (tmp = expression(true), semicolon(), tmp)
                 });
@@ -925,7 +924,7 @@ function parse($TEXT, options) {
 
               case "with":
                 if (S.input.has_directive("use strict")) {
-                    croak("SyntaxError: Strict mode may not include a with statement");
+                    croak("Strict mode may not include a with statement");
                 }
                 return new AST_With({
                     expression : parenthesised(),
@@ -945,7 +944,7 @@ function parse($TEXT, options) {
             // syntactically incorrect if it contains a
             // LabelledStatement that is enclosed by a
             // LabelledStatement with the same Identifier as label.
-            croak("SyntaxError: Label " + label.name + " defined twice");
+            croak("Label " + label.name + " defined twice");
         }
         expect(":");
         S.labels.push(label);
@@ -958,7 +957,7 @@ function parse($TEXT, options) {
             label.references.forEach(function(ref){
                 if (ref instanceof AST_Continue) {
                     ref = ref.label.start;
-                    croak("SyntaxError: Continue label `" + label.name + "` refers to non-IterationStatement.",
+                    croak("Continue label `" + label.name + "` refers to non-IterationStatement.",
                           ref.line, ref.col, ref.pos);
                 }
             });
@@ -978,11 +977,11 @@ function parse($TEXT, options) {
         if (label != null) {
             ldef = find_if(function(l){ return l.name == label.name }, S.labels);
             if (!ldef)
-                croak("SyntaxError: Undefined label " + label.name);
+                croak("Undefined label " + label.name);
             label.thedef = ldef;
         }
         else if (S.in_loop == 0)
-            croak("SyntaxError: " + type.TYPE + " not inside a loop or switch");
+            croak(type.TYPE + " not inside a loop or switch");
         semicolon();
         var stat = new type({ label: label });
         if (ldef) ldef.references.push(stat);
@@ -998,7 +997,7 @@ function parse($TEXT, options) {
                 : expression(true, true);
             if (is("operator", "in")) {
                 if (init instanceof AST_Var && init.definitions.length > 1)
-                    croak("SyntaxError: Only one variable declaration allowed in for..in loop");
+                    croak("Only one variable declaration allowed in for..in loop");
                 next();
                 return for_in(init);
             }
@@ -1148,7 +1147,7 @@ function parse($TEXT, options) {
             });
         }
         if (!bcatch && !bfinally)
-            croak("SyntaxError: Missing catch/finally blocks");
+            croak("Missing catch/finally blocks");
         return new AST_Try({
             body     : body,
             bcatch   : bcatch,
@@ -1242,7 +1241,7 @@ function parse($TEXT, options) {
             break;
           case "operator":
             if (!is_identifier_string(tok.value)) {
-                croak("SyntaxError: Invalid getter/setter name: " + tok.value,
+                croak("Invalid getter/setter name: " + tok.value,
                     tok.line, tok.col, tok.pos);
             }
             ret = _make_symbol(AST_SymbolRef);
@@ -1397,7 +1396,7 @@ function parse($TEXT, options) {
 
     function as_symbol(type, noerror) {
         if (!is("name")) {
-            if (!noerror) croak("SyntaxError: Name expected");
+            if (!noerror) croak("Name expected");
             return null;
         }
         var sym = _make_symbol(type);
@@ -1461,7 +1460,7 @@ function parse($TEXT, options) {
 
     function make_unary(ctor, op, expr) {
         if ((op == "++" || op == "--") && !is_assignable(expr))
-            croak("SyntaxError: Invalid use of " + op + " operator");
+            croak("Invalid use of " + op + " operator");
         return new ctor({ operator: op, expression: expr });
     };
 
@@ -1525,7 +1524,7 @@ function parse($TEXT, options) {
                     end      : prev()
                 });
             }
-            croak("SyntaxError: Invalid assignment");
+            croak("Invalid assignment");
         }
         return left;
     };
diff --git a/lib/utils.js b/lib/utils.js
index a0571d65..46adfd4c 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -78,13 +78,28 @@ function repeat_string(str, i) {
     return d;
 };
 
+function configure_error_stack(fn) {
+    Object.defineProperty(fn.prototype, "stack", {
+        get: function() {
+            var err = new Error(this.message);
+            err.name = this.name;
+            try {
+                throw err;
+            } catch(e) {
+                return e.stack;
+            }
+        }
+    });
+}
+
 function DefaultsError(msg, defs) {
-    Error.call(this, msg);
-    this.msg = msg;
+    this.message = msg;
     this.defs = defs;
 };
 DefaultsError.prototype = Object.create(Error.prototype);
 DefaultsError.prototype.constructor = DefaultsError;
+DefaultsError.prototype.name = "DefaultsError";
+configure_error_stack(DefaultsError);
 
 DefaultsError.croak = function(msg, defs) {
     throw new DefaultsError(msg, defs);
diff --git a/test/input/invalid/eof.js b/test/input/invalid/eof.js
new file mode 100644
index 00000000..330d5023
--- /dev/null
+++ b/test/input/invalid/eof.js
@@ -0,0 +1 @@
+foo, bar(
diff --git a/test/input/invalid/simple.js b/test/input/invalid/simple.js
new file mode 100644
index 00000000..98a07d20
--- /dev/null
+++ b/test/input/invalid/simple.js
@@ -0,0 +1 @@
+function f(a{}
diff --git a/test/input/invalid/tab.js b/test/input/invalid/tab.js
new file mode 100644
index 00000000..f209b8ee
--- /dev/null
+++ b/test/input/invalid/tab.js
@@ -0,0 +1 @@
+		foo(	xyz, 0abc);
diff --git a/test/mocha/cli.js b/test/mocha/cli.js
index 52c70935..c07eeee7 100644
--- a/test/mocha/cli.js
+++ b/test/mocha/cli.js
@@ -199,4 +199,43 @@ describe("bin/uglifyjs", function () {
             done();
         });
     });
+    it("Should fail with invalid syntax", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/simple.js';
+
+        exec(command, function (err, stdout, stderr) {
+            assert.ok(err);
+            var lines = stderr.split(/\n/);
+            assert.strictEqual(lines[0], "Parse error at test/input/invalid/simple.js:1,12");
+            assert.strictEqual(lines[1], "function f(a{}");
+            assert.strictEqual(lines[2], "            ^");
+            assert.strictEqual(lines[3], "SyntaxError: Unexpected token punc «{», expected punc «,»");
+            done();
+        });
+    });
+    it("Should fail with correct marking of tabs", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/tab.js';
+
+        exec(command, function (err, stdout, stderr) {
+            assert.ok(err);
+            var lines = stderr.split(/\n/);
+            assert.strictEqual(lines[0], "Parse error at test/input/invalid/tab.js:1,12");
+            assert.strictEqual(lines[1], "\t\tfoo(\txyz, 0abc);");
+            assert.strictEqual(lines[2], "\t\t    \t     ^");
+            assert.strictEqual(lines[3], "SyntaxError: Invalid syntax: 0abc");
+            done();
+        });
+    });
+    it("Should fail with correct marking at start of line", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/eof.js';
+
+        exec(command, function (err, stdout, stderr) {
+            assert.ok(err);
+            var lines = stderr.split(/\n/);
+            assert.strictEqual(lines[0], "Parse error at test/input/invalid/eof.js:2,0");
+            assert.strictEqual(lines[1], "foo, bar(");
+            assert.strictEqual(lines[2], "         ^");
+            assert.strictEqual(lines[3], "SyntaxError: Unexpected token: eof (undefined)");
+            done();
+        });
+    });
 });
diff --git a/test/mocha/comment.js b/test/mocha/comment.js
index 69cdb3d5..56470e0f 100644
--- a/test/mocha/comment.js
+++ b/test/mocha/comment.js
@@ -13,7 +13,7 @@ describe("Comment", function() {
 
         var fail = function(e) {
             return e instanceof uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Unexpected token: operator (>)" &&
+                e.message === "Unexpected token: operator (>)" &&
                 e.line === 2 &&
                 e.col === 0;
         }
@@ -36,7 +36,7 @@ describe("Comment", function() {
 
         var fail = function(e) {
             return e instanceof uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Unexpected token: operator (>)" &&
+                e.message === "Unexpected token: operator (>)" &&
                 e.line === 5 &&
                 e.col === 0;
         }
diff --git a/test/mocha/directives.js b/test/mocha/directives.js
index 82594758..bc763ae0 100644
--- a/test/mocha/directives.js
+++ b/test/mocha/directives.js
@@ -168,7 +168,7 @@ describe("Directives", function() {
                 throw new Error("Expected parser to fail");
             } catch (e) {
                 assert.strictEqual(e instanceof uglify.JS_Parse_Error, true);
-                assert.strictEqual(e.message, "SyntaxError: Unexpected token: punc (])");
+                assert.strictEqual(e.message, "Unexpected token: punc (])");
             }
 
             test_directive(tokenizer, tests[i]);
diff --git a/test/mocha/getter-setter.js b/test/mocha/getter-setter.js
index a292fa00..641a2026 100644
--- a/test/mocha/getter-setter.js
+++ b/test/mocha/getter-setter.js
@@ -71,7 +71,7 @@ describe("Getters and setters", function() {
         var fail = function(data) {
             return function (e) {
                 return e instanceof UglifyJS.JS_Parse_Error &&
-                    e.message === "SyntaxError: Invalid getter/setter name: " + data.operator;
+                    e.message === "Invalid getter/setter name: " + data.operator;
             };
         };
 
diff --git a/test/mocha/line-endings.js b/test/mocha/line-endings.js
index ef46bccd..10e2a1c5 100644
--- a/test/mocha/line-endings.js
+++ b/test/mocha/line-endings.js
@@ -50,7 +50,7 @@ describe("line-endings", function() {
         }
         var fail = function(e) {
             return e instanceof Uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Unexpected line terminator";
+                e.message === "Unexpected line terminator";
         }
         for (var i = 0; i < inputs.length; i++) {
             assert.throws(test(inputs[i]), fail);
diff --git a/test/mocha/minify.js b/test/mocha/minify.js
index 1b830cb5..0cf8c5c1 100644
--- a/test/mocha/minify.js
+++ b/test/mocha/minify.js
@@ -110,7 +110,7 @@ describe("minify", function() {
                     inSourceMap: "inline",
                     sourceMapInline: true
                 });
-            }, "multiple input and inline source map");
+            });
         });
         it("Should fail with SpiderMonkey and inline source map", function() {
             assert.throws(function() {
@@ -119,7 +119,7 @@ describe("minify", function() {
                     sourceMapInline: true,
                     spidermonkey: true
                 });
-            }, "SpiderMonkey and inline source map");
+            });
         });
     });
 
@@ -156,4 +156,19 @@ describe("minify", function() {
         });
     });
 
+    describe("JS_Parse_Error", function() {
+        it("should throw syntax error", function() {
+            assert.throws(function() {
+                Uglify.minify("function f(a{}", { fromString: true });
+            }, function(err) {
+                assert.ok(err instanceof Error);
+                assert.strictEqual(err.stack.split(/\n/)[0], "SyntaxError: Unexpected token punc «{», expected punc «,»");
+                assert.strictEqual(err.filename, 0);
+                assert.strictEqual(err.line, 1);
+                assert.strictEqual(err.col, 12);
+                return true;
+            });
+        });
+    });
+
 });
diff --git a/test/mocha/number-literal.js b/test/mocha/number-literal.js
index 8e05574a..e80a5313 100644
--- a/test/mocha/number-literal.js
+++ b/test/mocha/number-literal.js
@@ -15,7 +15,7 @@ describe("Number literals", function () {
         }
         var error = function(e) {
             return e instanceof uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Legacy octal literals are not allowed in strict mode";
+                e.message === "Legacy octal literals are not allowed in strict mode";
         }
         for (var i = 0; i < inputs.length; i++) {
             assert.throws(test(inputs[i]), error, inputs[i]);
diff --git a/test/mocha/string-literal.js b/test/mocha/string-literal.js
index eb9e6f1c..6e337a24 100644
--- a/test/mocha/string-literal.js
+++ b/test/mocha/string-literal.js
@@ -19,7 +19,7 @@ describe("String literals", function() {
 
         var error = function(e) {
             return e instanceof UglifyJS.JS_Parse_Error &&
-                e.message === "SyntaxError: Unterminated string constant";
+                e.message === "Unterminated string constant";
         };
 
         for (var input in inputs) {
@@ -49,7 +49,7 @@ describe("String literals", function() {
 
         var error = function(e) {
             return e instanceof UglifyJS.JS_Parse_Error &&
-                e.message === "SyntaxError: Legacy octal escape sequences are not allowed in strict mode";
+                e.message === "Legacy octal escape sequences are not allowed in strict mode";
         }
 
         for (var input in inputs) {
diff --git a/test/mocha/with.js b/test/mocha/with.js
index 734e1e13..a74ef41a 100644
--- a/test/mocha/with.js
+++ b/test/mocha/with.js
@@ -9,7 +9,7 @@ describe("With", function() {
         }
         var error = function(e) {
             return e instanceof uglify.JS_Parse_Error &&
-                e.message === "SyntaxError: Strict mode may not include a with statement";
+                e.message === "Strict mode may not include a with statement";
         }
         assert.throws(test, error);
     });