Xcode, ObjC, properties and linker

Either I am going crazy or Xcode behaves at least very different from the previous versions.

Checked with Xcode 12.2 and 12.3 beta.

Issue 1

You can do something like this without @implementation

Code Block 
@interface Bar : NSObject
- (void)foo;
@end

and project compiles


Issue 2 (or part of issue 1).

Foo is just an empty object with one no-op method -(void)bar.
Foo.m is not included in compiled sources.

Code Block 
#import "ViewController.h"
#import "Foo.h"
@interface ViewController ()
@property (nonatomic, strong) Foo *fooProperty;
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
/**
 Issue #2 (or maybe 1 part deux)
The star of the show is Foo *fooProperty.
Foo.m is not included in compiled sources.
But for some reason, there is no mention of it during the linking stage.
Uncomment next two lines and compilation fails
	Foo *fooInstance = [Foo new];
	[fooInstance bar];
Or you can uncomment this
	self.fooProperty = [Foo new];
**/
    [self.fooProperty bar];
}