builtin types could be usable as UDA, without being enclosed in parens

[dlangBugzillaToGithub]

basile-z reported this on 2019-12-22T17:32:13Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=20464

CC List

• Mathias LANG (@Geod24)

Description

Minor enhancement suggestion

---
template BasicTypeUDA(T)
{
    @T(0) int v1;
    @int(0) int v2; // not accepted by the parser but this is the same as v1 attribute when  `T` is an `int`.
}

alias WithInt = BasicTypeUDA!int;
---

possible by simplifying the current rule for UDA this way:

UserDefinedAttribute:
    @ ( ArgumentList )
-    @ Identifier
-    @ Identifier ( ArgumentListopt )
-    @ TemplateInstance
-    @ TemplateInstance ( ArgumentListopt )
+    @ BasicType
+    @ BasicType ( ArgumentListopt )

since BasicType covers Identifier, TemplateInstance, builtin types and even more. (https://dlang.org/spec/declaration.html#BasicType)

The @ guarantees that parsing will not become ambiguous.
This would simplify a bit the language by generalizing the use of the construction syntax, although we all know that `@Type(args)` is just the short for `@(Type(args))`.

[dlangBugzillaToGithub]

b2.temp commented on 2021-09-28T04:54:09Z

*** Issue 22338 has been marked as a duplicate of this issue. ***