SizedBox's layout behavior with incompatible constraints

main.dart

import 'package:flutter/widgets.dart';

void main() {
  final tight_200x200 = BoxConstraints.tight(Size(200, 200));
  final tight_100x100 = BoxConstraints.tight(Size(100, 100));
  final loose_0x0_to_200x200 = BoxConstraints.loose(Size(200, 200));
  
  // Mimic this example:
  //
  // SizeBox(
  //   width: 200,
  //   height: 200,
  //   SizedBox(
  //     width: 100,
  //     height: 100,
  //   ),
  // ),
  //
  // This:
  // 1. SizedBox#1 creates tight constraints 200x200
  // 2. SizedBox#2 attempts to apply additional tight constraints 100x100.
  //    These are two tight constraints with no overlap, so the additional constraints
  //    are ignored.
  print(tight_200x200.applyAdditionalConstraints(tight_100x100)); // 200x200
  
  // Mimic this example:
  //
  // SizeBox(
  //   width: 200,
  //   height: 200,
  //   Center(
  //     child: SizedBox(
  //       width: 100,
  //       height: 100,
  //     ),
  //   ),
  // ),
  //
  // This:
  // 1. SizedBox#1 creates tight constraints 200x200
  // 2. Center accepts tight constraints 200x200 and sizes itself 200x200.
  //    It creates loose constraints 0x0 to 200x200 and passes that down to its child.
  // 3. SizedBox#2 attempts to apply additional tight constraints 100x100.
  //    This _is_ within 0x0 to 200x200, so the resulting constraints are 100x100.
  print(loose_0x0_to_200x200.applyAdditionalConstraints(tight_100x100)); // 100x100
}

extension on BoxConstraints {
  BoxConstraints applyAdditionalConstraints(BoxConstraints additional) {
    // BoxConstraints.enforce respects the given constraints while trying to be
    // as close as possible to the additional constraints.
    return additional.enforce(this);
  }
}