From 23f8f4ba6d769f65da7b9dd1308f65d218300e36 Mon Sep 17 00:00:00 2001
From: Tan Li Hau <tanhauhau@users.noreply.github.com>
Date: Wed, 14 Jul 2021 01:33:55 +0800
Subject: [PATCH] [feat] centralise parse errors (#6519)

Co-authored-by: pngwn <hello@pngwn.io>
---
 src/compiler/parse/errors.ts                  | 192 ++++++++++++++++++
 src/compiler/parse/index.ts                   |  27 +--
 src/compiler/parse/read/context.ts            |  17 +-
 src/compiler/parse/read/expression.ts         |   6 +-
 src/compiler/parse/read/script.ts             |  19 +-
 src/compiler/parse/read/style.ts              |  29 +--
 src/compiler/parse/state/mustache.ts          |  71 +++----
 src/compiler/parse/state/tag.ts               | 104 +++-------
 .../samples/error-comment-unclosed/error.json |   2 +-
 9 files changed, 277 insertions(+), 190 deletions(-)
 create mode 100644 src/compiler/parse/errors.ts

diff --git a/src/compiler/parse/errors.ts b/src/compiler/parse/errors.ts
new file mode 100644
index 0000000000..b563b7572a
--- /dev/null
+++ b/src/compiler/parse/errors.ts
@@ -0,0 +1,192 @@
+// All parser errors should be listed and accessed from here
+
+import list from '../utils/list';
+
+/**
+ * @internal
+ */
+export default {
+	css_syntax_error: (message) => ({
+		code: 'css-syntax-error',
+		message
+	}),
+	duplicate_attribute: {
+		code: 'duplicate-attribute',
+		message: 'Attributes need to be unique'
+	},
+	duplicate_element: (slug: string, name: string) => ({
+		code: `duplicate-${slug}`,
+		message: `A component can only have one <${name}> tag`
+	}),
+	duplicate_style: {
+		code: 'duplicate-style',
+		message: 'You can only have one top-level <style> tag per component'
+	},
+	empty_attribute_shorthand: {
+		code: 'empty-attribute-shorthand',
+		message: 'Attribute shorthand cannot be empty'
+	},
+	empty_directive_name: (type: string) => ({
+		code: 'empty-directive-name',
+		message: `${type} name cannot be empty`
+	}),
+	empty_global_selector: {
+		code: 'css-syntax-error',
+		message: ':global() must contain a selector'
+	},
+	expected_block_type: {
+		code: 'expected-block-type',
+		message: 'Expected if, each or await'
+	},
+	expected_name: {
+		code: 'expected-name',
+		message: 'Expected name'
+	},
+	invalid_catch_placement_unclosed_block: (block) => ({
+		code: 'invalid-catch-placement',
+		message: `Expected to close ${block} before seeing {:catch} block`
+	}),
+	invalid_catch_placement_without_await: {
+		code: 'invalid-catch-placement',
+		message: 'Cannot have an {:catch} block outside an {#await ...} block'
+	},
+	invalid_component_definition: {
+		code: 'invalid-component-definition',
+		message: 'invalid component definition'
+	},
+	invalid_closing_tag_unopened: (name: string) => ({
+		code: 'invalid-closing-tag',
+		message: `</${name}> attempted to close an element that was not open`
+	}),
+	invalid_closing_tag_autoclosed: (name: string, reason: string) => ({
+		code: 'invalid-closing-tag',
+		message: `</${name}> attempted to close <${name}> that was already automatically closed by <${reason}>`
+	}),
+	invalid_debug_args: {
+		code: 'invalid-debug-args',
+		message:
+			'{@debug ...} arguments must be identifiers, not arbitrary expressions'
+	},
+	invalid_declaration: {
+		code: 'invalid-declaration',
+		message: 'Declaration cannot be empty'
+	},
+	invalid_directive_value: {
+		code: 'invalid-directive-value',
+		message: 'Directive value must be a JavaScript expression enclosed in curly braces'
+	},
+	invalid_elseif: {
+		code: 'invalid-elseif',
+		message: '\'elseif\' should be \'else if\''
+	},
+	invalid_elseif_placement_outside_if: {
+		code: 'invalid-elseif-placement',
+		message: 'Cannot have an {:else if ...} block outside an {#if ...} block'
+	},
+	invalid_elseif_placement_unclosed_block: (block) => ({
+		code: 'invalid-elseif-placement',
+		message: `Expected to close ${block} before seeing {:else if ...} block`
+	}),
+	invalid_else_placement_outside_if: {
+		code: 'invalid-else-placement',
+		message: 'Cannot have an {:else} block outside an {#if ...} or {#each ...} block'
+	},
+	invalid_else_placement_unclosed_block: (block) => ({
+		code: 'invalid-else-placement',
+		message: `Expected to close ${block} before seeing {:else} block`
+	}),
+	invalid_element_content: (slug: string, name: string) => ({
+		code: `invalid-${slug}-content`,
+		message: `<${name}> cannot have children`
+	}),
+	invalid_element_placement: (slug: string, name: string) => ({
+		code: `invalid-${slug}-placement`,
+		message: `<${name}> tags cannot be inside elements or blocks`
+	}),
+	invalid_ref_directive: (name: string) => ({
+		code: 'invalid-ref-directive',
+		message: `The ref directive is no longer supported — use \`bind:this={${name}}\` instead`
+	}),
+	invalid_ref_selector: {
+		code: 'invalid-ref-selector',
+		message: 'ref selectors are no longer supported'
+	},
+	invalid_self_placement: {
+		code: 'invalid-self-placement',
+		message: '<svelte:self> components can only exist inside {#if} blocks, {#each} blocks, or slots passed to components'
+	},
+	invalid_script_instance: {
+		code: 'invalid-script',
+		message: 'A component can only have one instance-level <script> element'
+	},
+	invalid_script_module: {
+		code: 'invalid-script',
+		message: 'A component can only have one <script context="module"> element'
+	},
+	invalid_script_context_attribute: {
+		code: 'invalid-script',
+		message: 'context attribute must be static'
+	},
+	invalid_script_context_value: {
+		code: 'invalid-script',
+		message: 'If the context attribute is supplied, its value must be "module"'
+	},
+	invalid_tag_name: {
+		code: 'invalid-tag-name',
+		message: 'Expected valid tag name'
+	},
+	invalid_tag_name_svelte_element: (tags: string[], match: string) => ({
+		code: 'invalid-tag-name',
+		message: `Valid <svelte:...> tag names are ${list(tags)}${
+			match ? ' (did you mean ' + match + '?)' : ''
+		}`
+	}),
+	invalid_then_placement_unclosed_block: (block) => ({
+		code: 'invalid-then-placement',
+		message: `Expected to close ${block} before seeing {:then} block`
+	}),
+	invalid_then_placement_without_await: {
+		code: 'invalid-then-placement',
+		message: 'Cannot have an {:then} block outside an {#await ...} block'
+	},
+	invalid_void_content: (name: string) => ({
+		code: 'invalid-void-content',
+		message: `<${name}> is a void element and cannot have children, or a closing tag`
+	}),
+	missing_component_definition: {
+		code: 'missing-component-definition',
+		message: '<svelte:component> must have a \'this\' attribute'
+	},
+	unclosed_script: {
+		code: 'unclosed-script',
+		message: '<script> must have a closing tag'
+	},
+	unclosed_style: {
+		code: 'unclosed-style',
+		message: '<style> must have a closing tag'
+	},
+	unclosed_comment: {
+		code: 'unclosed-comment',
+		message: 'comment was left open, expected -->'
+	},
+	unexpected_block_close: {
+		code: 'unexpected-block-close',
+		message: 'Unexpected block closing tag'
+	},
+	unexpected_eof: {
+		code: 'unexpected-eof',
+		message: 'Unexpected end of input'
+	},
+	unexpected_eof_token: (token: string) => ({
+		code: 'unexpected-eof',
+		message: `Unexpected ${token}`
+	}),
+	unexpected_token: (token: string) => ({
+		code: 'unexpected-token',
+		message: `Expected ${token}`
+	}),
+	unexpected_token_destructure: {
+		code: 'unexpected-token',
+		message: 'Expected identifier or destructure pattern'
+	}
+};
diff --git a/src/compiler/parse/index.ts b/src/compiler/parse/index.ts
index 27067caf26..836fb670cf 100644
--- a/src/compiler/parse/index.ts
+++ b/src/compiler/parse/index.ts
@@ -5,6 +5,7 @@ import { reserved } from '../utils/names';
 import full_char_code_at from '../utils/full_char_code_at';
 import { TemplateNode, Ast, ParserOptions, Fragment, Style, Script } from '../interfaces';
 import error from '../utils/error';
+import parser_errors from './errors';
 
 type ParserState = (parser: Parser) => (ParserState | void);
 
@@ -106,17 +107,18 @@ export class Parser {
 		});
 	}
 
-	eat(str: string, required?: boolean, message?: string) {
+	eat(str: string, required?: boolean, error?: { code: string, message: string }) {
 		if (this.match(str)) {
 			this.index += str.length;
 			return true;
 		}
 
 		if (required) {
-			this.error({
-				code: `unexpected-${this.index === this.template.length ? 'eof' : 'token'}`,
-				message: message || `Expected ${str}`
-			});
+			this.error(error ||
+				(this.index === this.template.length
+					? parser_errors.unexpected_eof_token(str)
+					: parser_errors.unexpected_token(str))
+			);
 		}
 
 		return false;
@@ -218,27 +220,18 @@ export default function parse(
 	// TODO we may want to allow multiple <style> tags —
 	// one scoped, one global. for now, only allow one
 	if (parser.css.length > 1) {
-		parser.error({
-			code: 'duplicate-style',
-			message: 'You can only have one top-level <style> tag per component'
-		}, parser.css[1].start);
+		parser.error(parser_errors.duplicate_style, parser.css[1].start);
 	}
 
 	const instance_scripts = parser.js.filter(script => script.context === 'default');
 	const module_scripts = parser.js.filter(script => script.context === 'module');
 
 	if (instance_scripts.length > 1) {
-		parser.error({
-			code: 'invalid-script',
-			message: 'A component can only have one instance-level <script> element'
-		}, instance_scripts[1].start);
+		parser.error(parser_errors.invalid_script_instance, instance_scripts[1].start);
 	}
 
 	if (module_scripts.length > 1) {
-		parser.error({
-			code: 'invalid-script',
-			message: 'A component can only have one <script context="module"> element'
-		}, module_scripts[1].start);
+		parser.error(parser_errors.invalid_script_module, module_scripts[1].start);
 	}
 
 	return {
diff --git a/src/compiler/parse/read/context.ts b/src/compiler/parse/read/context.ts
index a11dfb25c5..1e97baf8a7 100644
--- a/src/compiler/parse/read/context.ts
+++ b/src/compiler/parse/read/context.ts
@@ -9,6 +9,7 @@ import {
 } from '../utils/bracket';
 import { parse_expression_at } from '../acorn';
 import { Pattern } from 'estree';
+import parser_errors from '../errors';
 
 export default function read_context(
 	parser: Parser
@@ -27,10 +28,7 @@ export default function read_context(
 	}
 
 	if (!is_bracket_open(code)) {
-		parser.error({
-			code: 'unexpected-token',
-			message: 'Expected identifier or destructure pattern'
-		});
+		parser.error(parser_errors.unexpected_token_destructure);
 	}
 
 	const bracket_stack = [code];
@@ -42,12 +40,11 @@ export default function read_context(
 			bracket_stack.push(code);
 		} else if (is_bracket_close(code)) {
 			if (!is_bracket_pair(bracket_stack[bracket_stack.length - 1], code)) {
-				parser.error({
-					code: 'unexpected-token',
-					message: `Expected ${String.fromCharCode(
-						get_bracket_close(bracket_stack[bracket_stack.length - 1])
-					)}`
-				});
+				parser.error(
+					parser_errors.unexpected_token(
+						String.fromCharCode(get_bracket_close(bracket_stack[bracket_stack.length - 1]))
+					)
+				);
 			}
 			bracket_stack.pop();
 			if (bracket_stack.length === 0) {
diff --git a/src/compiler/parse/read/expression.ts b/src/compiler/parse/read/expression.ts
index f0f4e15c7a..5464a950ce 100644
--- a/src/compiler/parse/read/expression.ts
+++ b/src/compiler/parse/read/expression.ts
@@ -2,6 +2,7 @@ import { parse_expression_at } from '../acorn';
 import { Parser } from '../index';
 import { Node } from 'estree';
 import { whitespace } from '../../utils/patterns';
+import parser_errors from '../errors';
 
 export default function read_expression(parser: Parser): Node {
 	try {
@@ -20,10 +21,7 @@ export default function read_expression(parser: Parser): Node {
 			if (char === ')') {
 				num_parens -= 1;
 			} else if (!whitespace.test(char)) {
-				parser.error({
-					code: 'unexpected-token',
-					message: 'Expected )'
-				}, index);
+				parser.error(parser_errors.unexpected_token(')'), index);
 			}
 
 			index += 1;
diff --git a/src/compiler/parse/read/script.ts b/src/compiler/parse/read/script.ts
index db76cb8892..c9ac4ac344 100644
--- a/src/compiler/parse/read/script.ts
+++ b/src/compiler/parse/read/script.ts
@@ -2,25 +2,20 @@ import * as acorn from '../acorn';
 import { Parser } from '../index';
 import { Script } from '../../interfaces';
 import { Node, Program } from 'estree';
+import parser_errors from '../errors';
 
 function get_context(parser: Parser, attributes: any[], start: number): string {
 	const context = attributes.find(attribute => attribute.name === 'context');
 	if (!context) return 'default';
 
 	if (context.value.length !== 1 || context.value[0].type !== 'Text') {
-		parser.error({
-			code: 'invalid-script',
-			message: 'context attribute must be static'
-		}, start);
+		parser.error(parser_errors.invalid_script_context_attribute, start);
 	}
 
 	const value = context.value[0].data;
 
 	if (value !== 'module') {
-		parser.error({
-			code: 'invalid-script',
-			message: 'If the context attribute is supplied, its value must be "module"'
-		}, context.start);
+		parser.error(parser_errors.invalid_script_context_value, context.start);
 	}
 
 	return value;
@@ -28,13 +23,9 @@ function get_context(parser: Parser, attributes: any[], start: number): string {
 
 export default function read_script(parser: Parser, start: number, attributes: Node[]): Script {
 	const script_start = parser.index;
-	const error_message = {
-		code: 'unclosed-script',
-		message: '<script> must have a closing tag'
-	};
-	const data = parser.read_until(/<\/script\s*>/, error_message);
+	const data = parser.read_until(/<\/script\s*>/, parser_errors.unclosed_script);
 	if (parser.index >= parser.template.length) {
-		parser.error(error_message);
+		parser.error(parser_errors.unclosed_script);
 	}
 
 	const source = parser.template.slice(0, script_start).replace(/[^\n]/g, ' ') + data;
diff --git a/src/compiler/parse/read/style.ts b/src/compiler/parse/read/style.ts
index c951fa08c1..e4a885a8cc 100644
--- a/src/compiler/parse/read/style.ts
+++ b/src/compiler/parse/read/style.ts
@@ -3,18 +3,15 @@ import { walk } from 'estree-walker';
 import { Parser } from '../index';
 import { Node } from 'estree';
 import { Style } from '../../interfaces';
+import parser_errors from '../errors';
 
 export default function read_style(parser: Parser, start: number, attributes: Node[]): Style {
 	const content_start = parser.index;
-	const error_message = {
-		code: 'unclosed-style',
-		message: '<style> must have a closing tag'
-	};
 
-	const styles = parser.read_until(/<\/style\s*>/, error_message);
+	const styles = parser.read_until(/<\/style\s*>/, parser_errors.unclosed_style);
 
 	if (parser.index >= parser.template.length) {
-		parser.error(error_message);
+		parser.error(parser_errors.unclosed_style);
 	}
 
 	const content_end = parser.index;
@@ -31,10 +28,7 @@ export default function read_style(parser: Parser, start: number, attributes: No
 		});
 	} catch (err) {
 		if (err.name === 'SyntaxError') {
-			parser.error({
-				code: 'css-syntax-error',
-				message: err.message
-			}, err.offset);
+			parser.error(parser_errors.css_syntax_error(err.message), err.offset);
 		} else {
 			throw err;
 		}
@@ -52,26 +46,17 @@ export default function read_style(parser: Parser, start: number, attributes: No
 					const b = node.children[i + 1];
 
 					if (is_ref_selector(a, b)) {
-						parser.error({
-							code: 'invalid-ref-selector',
-							message: 'ref selectors are no longer supported'
-						}, a.loc.start.offset);
+						parser.error(parser_errors.invalid_ref_selector, a.loc.start.offset);
 					}
 				}
 			}
 
 			if (node.type === 'Declaration' && node.value.type === 'Value' && node.value.children.length === 0) {
-				parser.error({
-					code: 'invalid-declaration',
-					message: 'Declaration cannot be empty'
-				}, node.start);
+				parser.error(parser_errors.invalid_declaration, node.start);
 			}
 
 			if (node.type === 'PseudoClassSelector' && node.name === 'global' && node.children === null) {
-				parser.error({
-					code: 'css-syntax-error',
-					message: ':global() must contain a selector'
-				}, node.loc.start.offset);
+				parser.error(parser_errors.empty_global_selector, node.loc.start.offset);
 			}
 
 			if (node.loc) {
diff --git a/src/compiler/parse/state/mustache.ts b/src/compiler/parse/state/mustache.ts
index ccb2d1d487..cc3c24349c 100644
--- a/src/compiler/parse/state/mustache.ts
+++ b/src/compiler/parse/state/mustache.ts
@@ -6,6 +6,7 @@ import { trim_start, trim_end } from '../../utils/trim';
 import { to_string } from '../utils/node';
 import { Parser } from '../index';
 import { TemplateNode } from '../../interfaces';
+import parser_errors from '../errors';
 
 function trim_whitespace(block: TemplateNode, trim_before: boolean, trim_after: boolean) {
 	if (!block.children || block.children.length === 0) return; // AwaitBlock
@@ -66,10 +67,7 @@ export default function mustache(parser: Parser) {
 		} else if (block.type === 'KeyBlock') {
 			expected = 'key';
 		} else {
-			parser.error({
-				code: 'unexpected-block-close',
-				message: 'Unexpected block closing tag'
-			});
+			parser.error(parser_errors.unexpected_block_close);
 		}
 
 		parser.eat(expected, true);
@@ -98,10 +96,7 @@ export default function mustache(parser: Parser) {
 		parser.stack.pop();
 	} else if (parser.eat(':else')) {
 		if (parser.eat('if')) {
-			parser.error({
-				code: 'invalid-elseif',
-				message: "'elseif' should be 'else if'"
-			});
+			parser.error(parser_errors.invalid_elseif);
 		}
 
 		parser.allow_whitespace();
@@ -110,12 +105,11 @@ export default function mustache(parser: Parser) {
 		if (parser.eat('if')) {
 			const block = parser.current();
 			if (block.type !== 'IfBlock') {
-				parser.error({
-					code: 'invalid-elseif-placement',
-					message: parser.stack.some(block => block.type === 'IfBlock')
-						? `Expected to close ${to_string(block)} before seeing {:else if ...} block`
-						: 'Cannot have an {:else if ...} block outside an {#if ...} block'
-				});
+				parser.error(
+					parser.stack.some(block => block.type === 'IfBlock') 
+						? parser_errors.invalid_elseif_placement_unclosed_block(to_string(block)) 
+						: parser_errors.invalid_elseif_placement_outside_if
+				);
 			}
 
 			parser.require_whitespace();
@@ -146,12 +140,11 @@ export default function mustache(parser: Parser) {
 			// :else
 			const block = parser.current();
 			if (block.type !== 'IfBlock' && block.type !== 'EachBlock') {
-				parser.error({
-					code: 'invalid-else-placement',
-					message: parser.stack.some(block => block.type === 'IfBlock' || block.type === 'EachBlock')
-						? `Expected to close ${to_string(block)} before seeing {:else} block`
-						: 'Cannot have an {:else} block outside an {#if ...} or {#each ...} block'
-				});
+				parser.error(
+					parser.stack.some(block => block.type === 'IfBlock' || block.type === 'EachBlock') 
+						? parser_errors.invalid_else_placement_unclosed_block(to_string(block)) 
+						: parser_errors.invalid_else_placement_outside_if
+				);
 			}
 
 			parser.allow_whitespace();
@@ -172,21 +165,18 @@ export default function mustache(parser: Parser) {
 
 		if (is_then) {
 			if (block.type !== 'PendingBlock') {
-				parser.error({
-					code: 'invalid-then-placement',
-					message: parser.stack.some(block => block.type === 'PendingBlock')
-						? `Expected to close ${to_string(block)} before seeing {:then} block`
-						: 'Cannot have an {:then} block outside an {#await ...} block'
-				});
+				parser.error(
+					parser.stack.some(block => block.type === 'PendingBlock')
+						? parser_errors.invalid_then_placement_unclosed_block(to_string(block)) 
+						: parser_errors.invalid_then_placement_without_await 
+				);
 			}
 		} else {
 			if (block.type !== 'ThenBlock' && block.type !== 'PendingBlock') {
-				parser.error({
-					code: 'invalid-catch-placement',
-					message: parser.stack.some(block => block.type === 'ThenBlock' || block.type === 'PendingBlock')
-						? `Expected to close ${to_string(block)} before seeing {:catch} block`
-						: 'Cannot have an {:catch} block outside an {#await ...} block'
-				});
+				parser.error(parser.stack.some(block => block.type === 'ThenBlock' || block.type === 'PendingBlock')
+						? parser_errors.invalid_catch_placement_unclosed_block(to_string(block)) 
+						: parser_errors.invalid_catch_placement_without_await 
+				);
 			}
 		}
 
@@ -224,10 +214,7 @@ export default function mustache(parser: Parser) {
 		} else if (parser.eat('key')) {
 			type = 'KeyBlock';
 		} else {
-			parser.error({
-				code: 'expected-block-type',
-				message: 'Expected if, each, await or key'
-			});
+			parser.error(parser_errors.expected_block_type);
 		}
 
 		parser.require_whitespace();
@@ -286,12 +273,7 @@ export default function mustache(parser: Parser) {
 			if (parser.eat(',')) {
 				parser.allow_whitespace();
 				block.index = parser.read_identifier();
-				if (!block.index) {
-					parser.error({
-						code: 'expected-name',
-						message: 'Expected name'
-					});
-				}
+				if (!block.index) parser.error(parser_errors.expected_name);
 
 				parser.allow_whitespace();
 			}
@@ -371,10 +353,7 @@ export default function mustache(parser: Parser) {
 
 			identifiers.forEach(node => {
 				if (node.type !== 'Identifier') {
-					parser.error({
-						code: 'invalid-debug-args',
-						message: '{@debug ...} arguments must be identifiers, not arbitrary expressions'
-					}, node.start);
+					parser.error(parser_errors.invalid_debug_args, node.start);
 				}
 			});
 
diff --git a/src/compiler/parse/state/tag.ts b/src/compiler/parse/state/tag.ts
index 5aacc3e8b2..c7def68f6e 100644
--- a/src/compiler/parse/state/tag.ts
+++ b/src/compiler/parse/state/tag.ts
@@ -6,7 +6,7 @@ import { is_void } from '../../utils/names';
 import { Parser } from '../index';
 import { Directive, DirectiveType, TemplateNode, Text } from '../../interfaces';
 import fuzzymatch from '../../utils/fuzzymatch';
-import list from '../../utils/list';
+import parser_errors from '../errors';
 
 // eslint-disable-next-line no-useless-escape
 const valid_tag_name = /^\!?[a-zA-Z]{1,}:?[a-zA-Z0-9\-]*/;
@@ -58,7 +58,7 @@ export default function tag(parser: Parser) {
 
 	if (parser.eat('!--')) {
 		const data = parser.read_until(/-->/);
-		parser.eat('-->', true, 'comment was left open, expected -->');
+		parser.eat('-->', true, parser_errors.unclosed_comment);
 
 		parser.current().children.push({
 			start,
@@ -81,24 +81,18 @@ export default function tag(parser: Parser) {
 				(name === 'svelte:window' || name === 'svelte:body') &&
 				parser.current().children.length
 			) {
-				parser.error({
-					code: `invalid-${slug}-content`,
-					message: `<${name}> cannot have children`
-				}, parser.current().children[0].start);
+				parser.error(
+					parser_errors.invalid_element_content(slug, name), 
+					parser.current().children[0].start
+				);
 			}
 		} else {
 			if (name in parser.meta_tags) {
-				parser.error({
-					code: `duplicate-${slug}`,
-					message: `A component can only have one <${name}> tag`
-				}, start);
+				parser.error(parser_errors.duplicate_element(slug, name), start);
 			}
 
 			if (parser.stack.length > 1) {
-				parser.error({
-					code: `invalid-${slug}-placement`,
-					message: `<${name}> tags cannot be inside elements or blocks`
-				}, start);
+				parser.error(parser_errors.invalid_element_placement(slug, name), start);
 			}
 
 			parser.meta_tags[name] = true;
@@ -125,10 +119,7 @@ export default function tag(parser: Parser) {
 
 	if (is_closing_tag) {
 		if (is_void(name)) {
-			parser.error({
-				code: 'invalid-void-content',
-				message: `<${name}> is a void element and cannot have children, or a closing tag`
-			}, start);
+			parser.error(parser_errors.invalid_void_content(name), start);
 		}
 
 		parser.eat('>', true);
@@ -136,13 +127,10 @@ export default function tag(parser: Parser) {
 		// close any elements that don't have their own closing tags, e.g. <div><p></div>
 		while (parent.name !== name) {
 			if (parent.type !== 'Element') {
-				const message = parser.last_auto_closed_tag && parser.last_auto_closed_tag.tag === name
-					? `</${name}> attempted to close <${name}> that was already automatically closed by <${parser.last_auto_closed_tag.reason}>`
-					: `</${name}> attempted to close an element that was not open`;
-				parser.error({
-					code: 'invalid-closing-tag',
-					message
-				}, start);
+				const error = parser.last_auto_closed_tag && parser.last_auto_closed_tag.tag === name
+					? parser_errors.invalid_closing_tag_autoclosed(name, parser.last_auto_closed_tag.reason)
+					: parser_errors.invalid_closing_tag_unopened(name);
+				parser.error(error, start);
 			}
 
 			parent.end = start;
@@ -180,18 +168,12 @@ export default function tag(parser: Parser) {
 	if (name === 'svelte:component') {
 		const index = element.attributes.findIndex(attr => attr.type === 'Attribute' && attr.name === 'this');
 		if (!~index) {
-			parser.error({
-				code: 'missing-component-definition',
-				message: "<svelte:component> must have a 'this' attribute"
-			}, start);
+			parser.error(parser_errors.missing_component_definition, start);
 		}
 
 		const definition = element.attributes.splice(index, 1)[0];
 		if (definition.value === true || definition.value.length !== 1 || definition.value[0].type === 'Text') {
-			parser.error({
-				code: 'invalid-component-definition',
-				message: 'invalid component definition'
-			}, definition.start);
+			parser.error(parser_errors.invalid_component_definition, definition.start);
 		}
 
 		element.expression = definition.value[0].expression;
@@ -256,10 +238,7 @@ function read_tag_name(parser: Parser) {
 		}
 
 		if (!legal) {
-			parser.error({
-				code: 'invalid-self-placement',
-				message: '<svelte:self> components can only exist inside {#if} blocks, {#each} blocks, or slots passed to components'
-			}, start);
+			parser.error(parser_errors.invalid_self_placement, start);
 		}
 
 		return 'svelte:self';
@@ -276,20 +255,14 @@ function read_tag_name(parser: Parser) {
 	if (name.startsWith('svelte:')) {
 		const match = fuzzymatch(name.slice(7), valid_meta_tags);
 
-		let message = `Valid <svelte:...> tag names are ${list(valid_meta_tags)}`;
-		if (match) message += ` (did you mean '${match}'?)`;
-
-		parser.error({
-			code: 'invalid-tag-name',
-			message
-		}, start);
+		parser.error(
+			parser_errors.invalid_tag_name_svelte_element(valid_meta_tags, match), 
+			start
+		);
 	}
 
 	if (!valid_tag_name.test(name)) {
-		parser.error({
-			code: 'invalid-tag-name',
-			message: 'Expected valid tag name'
-		}, start);
+		parser.error(parser_errors.invalid_tag_name, start);
 	}
 
 	return name;
@@ -300,10 +273,7 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 
 	function check_unique(name: string) {
 		if (unique_names.has(name)) {
-			parser.error({
-				code: 'duplicate-attribute',
-				message: 'Attributes need to be unique'
-			}, start);
+			parser.error(parser_errors.duplicate_attribute, start);
 		}
 		unique_names.add(name);
 	}
@@ -331,10 +301,7 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 			parser.eat('}', true);
 
 			if (name === null) {
-				parser.error({
-					code: 'empty-attribute-shorthand',
-					message: 'Attribute shorthand cannot be empty'
-				}, start);
+				parser.error(parser_errors.empty_attribute_shorthand, start);
 			}
 
 			check_unique(name);
@@ -376,20 +343,14 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 		value = read_attribute_value(parser);
 		end = parser.index;
 	} else if (parser.match_regex(/["']/)) {
-		parser.error({
-			code: 'unexpected-token',
-			message: 'Expected ='
-		}, parser.index);
+		parser.error(parser_errors.unexpected_token('='), parser.index);
 	}
 
 	if (type) {
 		const [directive_name, ...modifiers] = name.slice(colon_index + 1).split('|');
 
 		if (directive_name === '') {
-			parser.error({
-				code: 'empty-directive-name',
-				message: `${type} name cannot be empty`
-			}, start + colon_index + 1);
+			parser.error(parser_errors.empty_directive_name(type), start + colon_index + 1);
 		}
 
 		if (type === 'Binding' && directive_name !== 'this') {
@@ -399,18 +360,12 @@ function read_attribute(parser: Parser, unique_names: Set<string>) {
 		}
 
 		if (type === 'Ref') {
-			parser.error({
-				code: 'invalid-ref-directive',
-				message: `The ref directive is no longer supported — use \`bind:this={${directive_name}}\` instead`
-			}, start);
+			parser.error(parser_errors.invalid_ref_directive(directive_name), start);
 		}
 
 		if (value[0]) {
 			if ((value as any[]).length > 1 || value[0].type === 'Text') {
-				parser.error({
-					code: 'invalid-directive-value',
-					message: 'Directive value must be a JavaScript expression enclosed in curly braces'
-				}, value[0].start);
+				parser.error(parser_errors.invalid_directive_value, value[0].start);
 			}
 		}
 
@@ -530,8 +485,5 @@ function read_sequence(parser: Parser, done: () => boolean): TemplateNode[] {
 		}
 	}
 
-	parser.error({
-		code: 'unexpected-eof',
-		message: 'Unexpected end of input'
-	});
+	parser.error(parser_errors.unexpected_eof);
 }
diff --git a/test/parser/samples/error-comment-unclosed/error.json b/test/parser/samples/error-comment-unclosed/error.json
index 8e355fb821..95fa28c35a 100644
--- a/test/parser/samples/error-comment-unclosed/error.json
+++ b/test/parser/samples/error-comment-unclosed/error.json
@@ -1,5 +1,5 @@
 {
-	"code": "unexpected-eof",
+	"code": "unclosed-comment",
 	"message": "comment was left open, expected -->",
 	"start": {
 		"line": 1,