test/Sema/type_eraser.swift

// RUN: %target-swift-frontend -typecheck -disable-availability-checking -dump-ast %s | %FileCheck %s

class AnyP: P {
  init<T: P>(erasing: T) {}
}

@_typeEraser(AnyP)
protocol P {}

struct ConcreteP: P, Hashable {}

// CHECK-LABEL: testBasic
dynamic func testBasic() -> some P {
  // CHECK: underlying_to_opaque_expr{{.*}}'some P'
  // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
  // CHECK: call_expr type='ConcreteP'
  ConcreteP()
}

// CHECK-LABEL: testTypeAlias
typealias AliasForP = P
dynamic func testTypeAlias() -> some AliasForP {
  // CHECK: underlying_to_opaque_expr{{.*}}'some P'
  // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
  // CHECK: call_expr type='ConcreteP'
  ConcreteP()
}

// CHECK-LABEL: testNoDynamic
func testNoDynamic() -> some P {
  // CHECK: underlying_to_opaque_expr{{.*}}'some P'
  // CHECK-NEXT: call_expr type='ConcreteP'
  ConcreteP()
}

// CHECK-LABEL: testNoOpaque
dynamic func testNoOpaque() -> P {
  // CHECK: erasure_expr implicit type='P'
  // CHECK-NEXT: normal_conformance type=ConcreteP protocol=P
  // CHECK-NEXT: call_expr type='ConcreteP'
  ConcreteP()
}

// CHECK-LABEL: testComposition
typealias Composition = P & Hashable
dynamic func testComposition() -> some Composition {
  // CHECK: underlying_to_opaque_expr{{.*}}'some Hashable & P'
  // CHECK-NEXT: call_expr type='ConcreteP'
  ConcreteP()
}

// CHECK-LABEL: struct_decl{{.*}}Builder
@resultBuilder
struct Builder {
  static func buildBlock(_ params: P...) -> ConcreteP {
    return ConcreteP()
  }
}

// CHECK-LABEL: TestResultBuilder
class TestResultBuilder {
  // CHECK-LABEL: testTransformFnBody
  @Builder dynamic var testTransformFnBody: some P {
    // CHECK: return_stmt
    // CHECK-NEXT: underlying_to_opaque_expr implicit type='some P'
    // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
    // CHECK: declref_expr implicit type='@lvalue ConcreteP'
    ConcreteP()
  }

  // CHECK-LABEL: func_decl{{.*}}takesBuilder
  func takesBuilder(@Builder closure: () -> ConcreteP) -> ConcreteP { closure() }

  // CHECK-LABEL: testClosureBuilder
  dynamic var testClosureBuilder: some P {
    // CHECK: underlying_to_opaque_expr implicit type='some P'
    // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
    // CHECK: closure_expr type='() -> ConcreteP'
    takesBuilder {
      // CHECK: return_stmt
      // CHECK-NEXT: load_expr implicit type='ConcreteP'
      ConcreteP()
    }
  }
}

// CHECK-LABEL: class_decl{{.*}}DynamicReplacement
class DynamicReplacement {
  dynamic func testDynamicReplaceable() -> some P {
    // CHECK: underlying_to_opaque_expr implicit type='some P'
    // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
    // CHECK: call_expr type='ConcreteP'
    ConcreteP()
  }
}

// CHECK-LABEL: extension_decl{{.*}}DynamicReplacement
extension DynamicReplacement {
  // CHECK-LABEL: testDynamicReplacement
  @_dynamicReplacement(for: testDynamicReplaceable)
  func testDynamicReplacement() -> some P {
    print("not single expr return")
    // CHECK: return_stmt
    // CHECK-NEXT: underlying_to_opaque_expr implicit type='some P'
    // CHECK-NEXT: call_expr implicit type='AnyP'{{.*}}arg_labels=erasing:
    // CHECK: call_expr type='ConcreteP'
    return ConcreteP()
  }
}