Unified: Synthesize implicit Swift initializers

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: hvitved

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

@@ -1228,7 +1228,8 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
             =>
             (equality_type_constraint left: {left} right: {right})
         ),
-        // Class declaration with body containing members
+        // Class declaration with body containing members. If the class has no
+        // explicit initializer, add Swift's implicit parameter-less `init`.
         rule!(
             (classDecl
                 classKeyword: @@kind
@@ -1241,15 +1242,29 @@ fn translation_rules() -> Vec<Rule<SwiftContext>> {
                 genericWhereClause: (genericWhereClause requirements: _* @declaration_constraints)?
                 memberBlock: (memberBlock members: _* @members))
             =>
-            (class_like_declaration
-                modifier: (modifier #{kind})
-                modifier: {mods}
-                name_node: (identifier #{name})
-                type_parameter: {params}
-                type_constraint: {parameter_constraints}
-                type_constraint: {declaration_constraints}
-                base_type: {bases.into_iter().map(|ty| tree!((base_type type: {ty})))}
-                member: {members})
+            class_like_declaration {
+                let has_explicit_initializer = members.iter().any(|member| {
+                    ctx.ast
+                        .get_node(*member)
+                        .is_some_and(|node| node.kind_name() == "constructor_declaration")
+                });
+                let implicit_initializer = (!has_explicit_initializer).then(|| {
+                    tree!((constructor_declaration
+                        modifier: (modifier "generated")
+                        name_node: (identifier "init")
+                        body: (block)))
+                });
+                tree!((class_like_declaration
+                    modifier: (modifier #{kind})
+                    modifier: {mods}
+                    name_node: (identifier #{name})
+                    type_parameter: {params}
+                    type_constraint: {parameter_constraints}
+                    type_constraint: {declaration_constraints}
+                    base_type: {bases.into_iter().map(|ty| tree!((base_type type: {ty})))}
+                    member: {members}
+                    member: {implicit_initializer}))
+            }
         ),
         // Enum class declaration: same as a regular class but with an enum body.
         rule!(

unified/extractor/tests/corpus/swift/expressions/super-expression.output

@@ -157,6 +157,10 @@ top_level source="⟨body⟩"
             function_declaration source="func ⟨name_node⟩() ⟨body⟩"
               name_node: identifier "update" source="update"
               body: block "{}" source="{}"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""
         class_like_declaration source="⟨modifier⟩ ⟨name_node⟩: ⟨base_type⟩ {\n  ⟨member⟩\n}"
           modifier: modifier "class" source="class"
           name_node: identifier "Derived" source="Derived"
@@ -182,3 +186,7 @@ top_level source="⟨body⟩"
                         member_access_expr source="⟨base⟩.⟨member_name_node⟩"
                           base: super_expr "super" source="super"
                           member_name_node: identifier "update" source="update"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/functions/constructor-call-with-type-arguments.output

@@ -83,12 +83,22 @@ top_level source="⟨body⟩"
         class_like_declaration source="⟨modifier⟩ ⟨name_node⟩ {}"
           modifier: modifier "class" source="class"
           name_node: identifier "Foo" source="Foo"
+          member:
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""
         class_like_declaration source="⟨modifier⟩ ⟨name_node⟩<⟨type_parameter⟩> {}"
           modifier: modifier "class" source="class"
           name_node: identifier "C" source="C"
           type_parameter:
             type_parameter source="⟨name_node⟩"
               name_node: identifier "T" source="T"
+          member:
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""
         variable_declaration source="⟨modifier⟩ ⟨pattern⟩ = ⟨value⟩"
           modifier: modifier "let" source="let"
           pattern: identifier "x" source="x"

unified/extractor/tests/corpus/swift/types/class-function.output

@@ -55,3 +55,7 @@ top_level source="⟨body⟩"
               modifier: modifier "class" source="class"
               name_node: identifier "make" source="make"
               body: block "{}" source="{}"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/class-inheritance.output

@@ -38,3 +38,8 @@ top_level source="⟨body⟩"
           base_type:
             base_type source="⟨type⟩"
               type: identifier "Animal" source="Animal"
+          member:
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/class-with-method.output

@@ -94,3 +94,7 @@ top_level source="⟨body⟩"
                       left: identifier "n" source="n"
                       operator: infix_operator "+=" source="+="
                       right: int_literal "1" source="1"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/class-with-multiple-base-types.output

@@ -45,3 +45,8 @@ top_level source="⟨body⟩"
               type: identifier "Control" source="Control"
             base_type source="⟨type⟩"
               type: identifier "Drawable" source="Drawable"
+          member:
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/class-with-stored-properties.output

@@ -73,3 +73,7 @@ top_level source="⟨body⟩"
               modifier: modifier "var" source="var"
               pattern: identifier "y" source="y"
               type: identifier "Int" source="Int"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/computed-property.output

@@ -127,3 +127,7 @@ top_level source="⟨body⟩"
                           left: identifier "w" source="w"
                           operator: infix_operator "*" source="*"
                           right: identifier "h" source="h"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""

unified/extractor/tests/corpus/swift/types/conditional-compilation-in-class-body.output

@@ -84,4 +84,9 @@ top_level source="⟨body⟩"
         class_like_declaration source="⟨modifier⟩ ⟨name_node⟩ {\n⟨member⟩\n}"
           modifier: modifier "class" source="class"
           name_node: identifier "C" source="C"
-          member: unsupported_node "#if DEBUG\n    init(x: Int) {}\n    deinit {}\n#endif" source="#if DEBUG\n    init(x: Int) {}\n    deinit {}\n#endif"
+          member:
+            unsupported_node "#if DEBUG\n    init(x: Int) {}\n    deinit {}\n#endif" source="#if DEBUG\n    init(x: Int) {}\n    deinit {}\n#endif"
+            constructor_declaration source=""
+              modifier: modifier "generated" source=""
+              name_node: identifier "init" source=""
+              body: block source=""