[timotheeguerin]

Stacked on top of the declarations-as-expressions work (microsoft#11019, branch decl-expr).

Enables applying decorators inline to model, enum, union, and scalar declarations used in expression position.

model Foo {
  status: @doc("the current status") enum { active, inactive };
  inner: @doc("nested model") model Inner { x: string };
}

Changes

• Parser (parser.ts): the @ case in parsePrimaryExpression now parses a decorator list and, when followed by a model/enum/union/scalar keyword, dispatches to the corresponding parse*Statement (with pos captured at @ so the node span includes the decorators). Decorators before any other expression still report invalid-decorator-location ("Cannot decorate expression.").
• Grammar spec (spec.emu.html): added the optional DecoratorList? prefix to the four *DeclarationExpression productions.
• Formatter (printer.ts): the four print*Statement printers now pass tryInline: isInExpressionPosition(path), keeping decorators on the same line in expression position while statement-position decorators still break to their own line. Output is idempotent.

Tests

• 5 checker tests: @doc applies to anonymous enum, named model, keyword union, and scalar declaration expressions (verified via getDoc), plus a negative case (decorator before a string reference still rejected).
• 6 formatter tests covering inline decorators on each kind.
• Full compiler suite: 4034 passed / 6 skipped.

Discussion

• No checker changes were required — parse*Statement already plumbs decorators onto the AST node and the checker already applies node.decorators. The only blocker was the parser discarding decorators in expression position.

[timotheeguerin]

Closing in favor of bundling this work directly into the base declaration-expressions PR microsoft#11019. Following a design-meeting decision, inline decorators (and augment decorators) on declaration expressions are now part of that single feature rather than a separate stacked change. The changes have been moved onto the decl-expr branch (commit 03f837d).