fix(syntax): allow block comments between members

`skipTrivia` skipped `// line comments` but not `/* block comments */`, so one
written between two page or component members failed with a bare "Unexpected
character '/'". Block comments inside a braced body already worked, which made
the failure look arbitrary: the same comment parsed or did not depending on
whether it happened to sit inside a block.

`startsWithBlockComment` now skips only whitespace and line comments, so
`props {}` keeps refusing block comments with its own explained error rather
than silently swallowing one and dropping the declaration after it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/syntax/src/tokenizer.ts

@@ -163,8 +163,13 @@ export class Lexer {
   pos = 0;
   constructor(public readonly src: string) {}
 
-  /** Skip whitespace and `// line comments`. */
-  private skipTrivia(): void {
+  /**
+   * Skip whitespace and `// line comments`, but NOT block comments.
+   *
+   * Kept separate from `skipTrivia` so `startsWithBlockComment` can still see a
+   * block comment that `skipTrivia` would otherwise consume.
+   */
+  private skipWhitespaceAndLineComments(): void {
     const { src } = this;
     while (this.pos < src.length) {
       const c = src[this.pos]!;
@@ -180,9 +185,35 @@ export class Lexer {
     }
   }
 
-  /** True when the next non-trivia characters open a block comment. */
+  /**
+   * Skip whitespace, line comments and block comments.
+   *
+   * Block comments used to be skipped only inside a braced body, so one written
+   * between two members failed with a bare "Unexpected character '/'" -- the
+   * same comment parsed or did not depending on where it sat.
+   */
+  private skipTrivia(): void {
+    const { src } = this;
+    while (this.pos < src.length) {
+      this.skipWhitespaceAndLineComments();
+      if (src[this.pos] === "/" && src[this.pos + 1] === "*") {
+        const close = src.indexOf("*/", this.pos + 2);
+        this.pos = close === -1 ? src.length : close + 2;
+        continue;
+      }
+      break;
+    }
+  }
+
+  /**
+   * True when the next non-trivia characters open a block comment.
+   *
+   * Deliberately skips only whitespace and line comments: `props {}` refuses
+   * block comments with an explained error, and that check must run before
+   * `skipTrivia` would swallow the comment and drop a declaration silently.
+   */
   startsWithBlockComment(): boolean {
-    this.skipTrivia();
+    this.skipWhitespaceAndLineComments();
     return this.src[this.pos] === "/" && this.src[this.pos + 1] === "*";
   }
 

packages/syntax/test/syntax.test.ts

@@ -286,3 +286,54 @@ test("division is not treated as a regex literal", () => {
 `;
   expect(parse(source).name).toBe("P");
 });
+
+// `skipTrivia` skipped `// line comments` but not `/* block comments */`, so a
+// block comment between page or component members failed with a bare
+// "Unexpected character '/'". Block comments inside a braced body already
+// worked, which made the failure look arbitrary: the same comment moved a few
+// lines parsed or did not depending on whether it sat inside a block.
+test("block comments are allowed between members", () => {
+  const page = `page P {
+  /* Explains the state below. */
+  state x = 1
+
+  /* Explains the view below. */
+  view { <div>{x}</div> }
+}
+`;
+  expect(parse(page).name).toBe("P");
+
+  const component = `component C {
+  /* A note about this component. */
+  state y = 2
+  view { <p>{y}</p> }
+}
+`;
+  expect(parse(component).name).toBe("C");
+
+  // A block comment before the opening brace, and a multi-line one.
+  const spaced = `/* Leading note. */
+page Q {
+  /*
+   * A multi-line note about the view.
+   */
+  view { <div>ok</div> }
+}
+`;
+  expect(parse(spaced).name).toBe("Q");
+});
+
+// Block comments inside props {} stay a deliberate, explained error -- the
+// props parser cannot represent them, and silently skipping one would drop a
+// declaration the author believed was there.
+test("a block comment inside props is still refused with its own message", () => {
+  const source = `component C {
+  props {
+    /* not allowed here */
+    name: string
+  }
+  view { <p>{name}</p> }
+}
+`;
+  expect(() => parse(source)).toThrow("Block comments are not allowed inside props");
+});