Enum AttrKey 

pub enum AttrKey {
    Static(Symbol),
    Dynamic(Expr),
}

One component of an attribute path, after constant-folding.

The static/dynamic split is a constant-fold on node kind, not “quoted vs unquoted” — which is the trap that makes intuition wrong here:

a          Ident        -> STATIC
"a"        Str, no interpolation
                        -> STATIC   (`{ "a" = 1; a = 2; }` is a duplicate)
${"a"}     Dynamic wrapping a pure Str
                        -> STATIC   (`{ ${"a"} = 1; a = 2; }` is a duplicate)
"${"a"}"   Str WITH interpolation
                        -> DYNAMIC  (parses fine; errors only when FORCED)
${"a"+""}  Dynamic wrapping a non-Str
                        -> DYNAMIC

Getting this wrong in the permissive direction turns a currently-correct answer into a throw: { a = {p=1;}; ${"a"} = {q=2;}; } merges in nix, and sui already agrees with it today.

Variants

Static(Symbol)

Folded to a compile-time-known name.

Dynamic(Expr)

Genuinely dynamic — resolved, and checked for collisions, only when the enclosing attrset is FORCED. Never participates in a parse-time merge.

Trait Implementations

impl Clone for AttrKey

fn clone(&self) -> AttrKey

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AttrKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.