unified: Desugar capture declaration list

Author: asgerf

unified/extractor/src/languages/swift/swift.rs

@@ -795,7 +795,7 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
                 body: (block stmt: {body}))
         ),
         // A closure capture (`[weak self]`, `[x]`, `[y = expr]`). The optional
-        // ownership specifier (`weak`/`unowned`) becomes a modifier; the
+        // ownership specifier (`weak`/`unowned`) becomes a modifier and a unary_expr; the
         // captured name becomes the bound `name_node`; an explicit capture
         // initializer (`[y = expr]`) becomes the bound value.
         rule!(
@@ -807,7 +807,18 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
             (variable_declaration
                 modifier: (modifier #{spec})?
                 pattern: (identifier #{name})
-                value: {val})
+                value: {
+                    // Expand [x] into [x = x]
+                    let value = match val {
+                        Some(val) => val,
+                        None => tree!((identifier #{name})),
+                    };
+                    // Expand [weak x] into a unary_expr, to represent the boxing in Optional.same
+                    match spec {
+                        Some(spec) => tree!((unary_expr operator: (prefix_operator #{spec}) operand: {value})),
+                        None => value,
+                    }
+                })
         ),
         // A closure parameter clause (`(x: Int, y)`) unwraps to its parameters.
         rule!((closureParameterClause parameters: _* @params) => parameter* { params }),

unified/extractor/tests/corpus/swift/closures/closure-with-capture-list.output

@@ -70,9 +70,13 @@ top_level source="⟨body⟩"
           value:
             function_expr source="{ [⟨capture_declaration⟩] in ⟨body⟩ }"
               capture_declaration:
-                variable_declaration source="⟨modifier⟩ ⟨pattern⟩"
+                variable_declaration source="⟨modifier⟩⟨value⟩⟨pattern⟩"
                   modifier: modifier "weak" source="weak"
                   pattern: identifier "self" source="self"
+                  value:
+                    unary_expr source="⟨operator⟩ ⟨operand⟩"
+                      operand: identifier "self" source="self"
+                      operator: prefix_operator "weak" source="weak"
               body:
                 block source="⟨stmt⟩"
                   stmt: