Consider this minimal Objective-C header: ```obj-c #import <Foundation/Foundation.h> @interface Foo : NSObject /** */- (void)foo; @end ``` If I run clang-format on it once, I get this diff against the original file: ```diff @@ -3,6 +3,7 @@ @interface Foo : NSObject /** - */- (void)foo; + */ +-(void)foo; @end ``` If I now run it again, I get this diff against the output of the first run: ```diff @@ -4,6 +4,6 @@ /** */ --(void)foo; +- (void)foo; @end ``` Ideally, running clang-format would be idempotent, so that CI that runs clang-format on the tree and fails on any observed changes can work correctly.