This commit introduces support for unhygienic macro expansion using the
`~ident` syntax. When an identifier is prefixed with a tilde (`~`)
within a macro template, it is no longer subject to hygienic renaming.
Instead, it directly refers to a binding in the call site's environment.
This allows macros to interact with variables defined outside the
macro's scope, such as:
- Modifying call-site variables.
- Capturing call-site variables as upvalues in closures.
- Defining new variables that are visible in the call site.
A new test case `test_macro_tilde_nonparam_assign` has been added to
verify this functionality. Previously, unhygienic escapes were
implicitly handled by `SyntaxKind::Identifier` if they were not macro
parameters. This change makes this behavior explicit and correctly
handles non-parameter identifiers by returning a bare symbol.
Brummel
9c5506b83e