diff --git a/.changeset/fix-type-identifier-in-tag.md b/.changeset/fix-type-identifier-in-tag.md
new file mode 100644
index 0000000000..8e88843536
--- /dev/null
+++ b/.changeset/fix-type-identifier-in-tag.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't mistake expressions starting with `type` (e.g. `{type === 'all' ? a : b}`) for TypeScript `type` declarations in tags
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/tag.js b/packages/svelte/src/compiler/phases/1-parse/state/tag.js
index 3c8eba4b26..de17183920 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/tag.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/tag.js
@@ -12,9 +12,9 @@ import { find_matching_bracket, match_bracket } from '../utils/bracket.js';
const regex_whitespace_with_closing_curly_brace = /\s*}/y;
const regex_supported_declaration = /(?:let|const)\b/y;
-// All except `type` are reserved keywords and cannot be used as variable names.
-// For type we check if it's not something like `type .x` / `type ()` / `type % 2` / ...
-const regex_unsupported_declaration = /(?:(?:var|interface|enum)\b)|(?:type\s+[^?.(`<[&|%^}])/y;
+const regex_unsupported_declaration = /(?:var|interface|enum)\b/y;
+// `type` is a contextual keyword; this is just a shape hint, confirmed by parsing.
+const regex_maybe_type_declaration = /type\s+[\p{ID_Start}_$]/uy;
const pointy_bois = { '<': '>' };
@@ -77,6 +77,26 @@ function read_declaration(parser) {
e.declaration_tag_invalid_type({ start, end: start + unsupported.length });
}
+ const type_alias_match = parser.match_regex(regex_maybe_type_declaration);
+ if (type_alias_match) {
+ const initial_comment_count = parser.root.comments.length;
+ /** @type {{ type: string; start: number; end: number } | undefined} */
+ let statement;
+ try {
+ statement = /** @type {{ type: string; start: number; end: number }} */ (
+ /** @type {unknown} */ (parse_statement_at(parser, parser.template, start))
+ );
+ } catch {
+ e.declaration_tag_invalid_type({ start, end: start + type_alias_match.length });
+ }
+ if (statement.type !== 'ExpressionStatement') {
+ e.declaration_tag_invalid_type(statement);
+ }
+ // discard probe comments so `read_expression` doesn't re-add them
+ parser.root.comments.length = initial_comment_count;
+ return null;
+ }
+
if (!parser.match_regex(regex_supported_declaration)) {
return null;
}
diff --git a/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/input.svelte b/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/input.svelte
new file mode 100644
index 0000000000..fa4195996e
--- /dev/null
+++ b/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/input.svelte
@@ -0,0 +1 @@
+{type instanceof /* probe */ Object}
diff --git a/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/output.json b/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/output.json
new file mode 100644
index 0000000000..4fe6468742
--- /dev/null
+++ b/packages/svelte/tests/parser-modern/samples/tag-type-identifier-probe-comment/output.json
@@ -0,0 +1,92 @@
+{
+ "css": null,
+ "js": [],
+ "start": 0,
+ "end": 36,
+ "type": "Root",
+ "fragment": {
+ "type": "Fragment",
+ "nodes": [
+ {
+ "type": "ExpressionTag",
+ "start": 0,
+ "end": 36,
+ "expression": {
+ "type": "BinaryExpression",
+ "start": 1,
+ "end": 35,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 1
+ },
+ "end": {
+ "line": 1,
+ "column": 35
+ }
+ },
+ "left": {
+ "type": "Identifier",
+ "start": 1,
+ "end": 5,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 1
+ },
+ "end": {
+ "line": 1,
+ "column": 5
+ }
+ },
+ "name": "type"
+ },
+ "operator": "instanceof",
+ "right": {
+ "type": "Identifier",
+ "start": 29,
+ "end": 35,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 29
+ },
+ "end": {
+ "line": 1,
+ "column": 35
+ }
+ },
+ "name": "Object",
+ "leadingComments": [
+ {
+ "type": "Block",
+ "value": " probe ",
+ "start": 17,
+ "end": 28
+ }
+ ]
+ }
+ }
+ }
+ ]
+ },
+ "options": null,
+ "comments": [
+ {
+ "type": "Block",
+ "value": " probe ",
+ "start": 17,
+ "end": 28,
+ "loc": {
+ "start": {
+ "line": 1,
+ "column": 17
+ },
+ "end": {
+ "line": 1,
+ "column": 28
+ }
+ }
+ }
+ ]
+}
diff --git a/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/_config.js b/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/_config.js
new file mode 100644
index 0000000000..52841fd48d
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/_config.js
@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+ html: `cast
generic-call
generic-call-space
`
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/main.svelte b/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/main.svelte
new file mode 100644
index 0000000000..693a360f55
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/declaration-tag-type-identifier/main.svelte
@@ -0,0 +1,16 @@
+
+
+
+ {#each assetTypes as type (type)}
+ - {type === 'all' ? 'All types' : type}
+ {/each}
+
+
+{'cast' as string}
+{type('generic-call')}
+{type ('generic-call-space')}
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/errors.json b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/errors.json
index 052636cddb..c1603f4139 100644
--- a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/errors.json
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/errors.json
@@ -3,11 +3,11 @@
"code": "declaration_tag_invalid_type",
"message": "Declaration tags must be `let` or `const` declarations",
"start": {
- "line": 14,
+ "line": 25,
"column": 2
},
"end": {
- "line": 14,
+ "line": 25,
"column": 8
}
}
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/input.svelte b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/input.svelte
index 129a8ac7ba..772c0931c0 100644
--- a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/input.svelte
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-2/input.svelte
@@ -10,6 +10,17 @@
{type ()}
{type [1]}
{type `tag`}
+ {type === 'all' ? 'All types' : type}
+ {type !== 'all'}
+ {type == 'all'}
+ {type != 'all'}
+ {type + 1}
+ {type - 1}
+ {type * 2}
+ {type / 2}
+ {type > 1}
+ {type instanceof Foo}
+ {type in foo}
{type foo = boolean}
{/if}
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/errors.json b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/errors.json
new file mode 100644
index 0000000000..a60f0055ae
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/errors.json
@@ -0,0 +1,14 @@
+[
+ {
+ "code": "declaration_tag_invalid_type",
+ "message": "Declaration tags must be `let` or `const` declarations",
+ "start": {
+ "line": 2,
+ "column": 1
+ },
+ "end": {
+ "line": 2,
+ "column": 33
+ }
+ }
+]
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/input.svelte b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/input.svelte
new file mode 100644
index 0000000000..2e5465b786
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-generic/input.svelte
@@ -0,0 +1,2 @@
+
+{type Foo = T[]}
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/errors.json b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/errors.json
new file mode 100644
index 0000000000..fb4ef28f3a
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/errors.json
@@ -0,0 +1,14 @@
+[
+ {
+ "code": "declaration_tag_invalid_type",
+ "message": "Declaration tags must be `let` or `const` declarations",
+ "start": {
+ "line": 2,
+ "column": 1
+ },
+ "end": {
+ "line": 2,
+ "column": 16
+ }
+ }
+]
diff --git a/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/input.svelte b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/input.svelte
new file mode 100644
index 0000000000..baae707898
--- /dev/null
+++ b/packages/svelte/tests/validator/samples/declaration-tag-invalid-type-unicode/input.svelte
@@ -0,0 +1,2 @@
+
+{type Ω = string}