Swift ran through the C-style lexical patterns, which never recognize
`func`. On a small file (`func realTarget()`, `func ghost()`, a class
method `caller` that calls `realTarget()` below a `/* ghost() */`
comment) the preview reported:
a.swift -> ghost (a.swift:2 declaration, a.swift:5 in a comment)
a.swift -> caller (its declaration line)
a.swift -> realTarget (its declaration line)
and missed the real call. Now:
caller -> realTarget (a.swift:7)
- Swift gets its own patterns: `func` declarations (with attributes and
modifiers), class/struct/enum/protocol/actor/extension declarations
(`class func` / `class var` are members, not classes), and imports.
- Block comments are masked across lines, nested as Swift allows, and a
`/*` inside a string literal does not open one. The masker is salvaged
from the unmerged language-parity branch (543bafc).
- Calls are attributed to their enclosing function through the existing
brace-scoped scopes, now that functions are recognized.
Test: tests/swift_preview.rs (functions and a class recognized, the call
attributed to `caller`, nothing from comments, nothing from the file
node); it failed before this change.
