better error message for invalid logic block placement

src/compiler/parse/errors.ts

@@ -107,6 +107,10 @@ export default {
 		code: `invalid-${slug}-placement`,
 		message: `<${name}> tags cannot be inside elements or blocks`
 	}),
+	invalid_logic_block_placement: (location: string, name: string) => ({
+		code: 'invalid-logic-block-placement',
+		message: `{#${name}} logic block cannot be ${location}`
+	}),
 	invalid_ref_directive: (name: string) => ({
 		code: 'invalid-ref-directive',
 		message: `The ref directive is no longer supported — use \`bind:this={${name}}\` instead`

src/compiler/parse/state/tag.ts

@@ -219,7 +219,8 @@ export default function tag(parser: Parser) {
 		element.children = read_sequence(
 			parser,
 			() =>
-				/^<\/textarea(\s[^>]*)?>/i.test(parser.template.slice(parser.index))
+				/^<\/textarea(\s[^>]*)?>/i.test(parser.template.slice(parser.index)),
+			'inside <textarea>'
 		);
 		parser.read(/^<\/textarea(\s[^>]*)?>/i);
 		element.end = parser.index;
@@ -473,7 +474,7 @@ function read_attribute_value(parser: Parser) {
 
 	let value;
 	try {
-		value = read_sequence(parser, () => !!parser.match_regex(regex));
+		value = read_sequence(parser, () => !!parser.match_regex(regex), 'in attribute value');
 	} catch (error) {
 		if (error.code === 'parse-error') {
 			// if the attribute value didn't close + self-closing tag
@@ -495,7 +496,7 @@ function read_attribute_value(parser: Parser) {
 	return value;
 }
 
-function read_sequence(parser: Parser, done: () => boolean): TemplateNode[] {
+function read_sequence(parser: Parser, done: () => boolean, location: string): TemplateNode[] {
 	let current_chunk: Text = {
 		start: parser.index,
 		end: null,
@@ -521,6 +522,13 @@ function read_sequence(parser: Parser, done: () => boolean): TemplateNode[] {
 			flush(parser.index);
 			return chunks;
 		} else if (parser.eat('{')) {
+			if (parser.match('#')) {
+				const index = parser.index - 1;
+				parser.eat('#');
+				const name = parser.read_until(/[^a-z]/);
+				parser.error(parser_errors.invalid_logic_block_placement(location, name), index);
+			}
+
 			flush(parser.index - 1);
 
 			parser.allow_whitespace();

test/validator/samples/logic-block-in-attribute/errors.json

@@ -0,0 +1,9 @@
+[
+	{
+		"code": "invalid-logic-block-placement",
+		"message": "{#if} logic block cannot be in attribute value",
+		"start": { "line": 1, "column": 12, "character": 12 },
+		"end": { "line": 1, "column": 12, "character": 12 },
+		"pos": 12
+	}
+]

test/validator/samples/logic-block-in-attribute/input.svelte

@@ -0,0 +1 @@
+<div style="{#if condition}a{/if}" />

test/validator/samples/logic-block-in-textarea/errors.json

@@ -0,0 +1,9 @@
+[
+	{
+		"code": "invalid-logic-block-placement",
+		"message": "{#each} logic block cannot be inside <textarea>",
+		"start": { "line": 2, "column": 1, "character": 12 },
+		"end": { "line": 2, "column": 1, "character": 12 },
+		"pos": 12
+	}
+]

test/validator/samples/logic-block-in-textarea/input.svelte

@@ -0,0 +1,5 @@
+<textarea>
+	{#each fruits as fruit}
+		{fruit}
+	{/each}
+</textarea>