The following should be legal Objective-C++ as far as I can tell. But it does not compile:
/*
* compile:
*
* gcc -c $(gnustep-config --objc-flags) -x objective-c++
*
* fails for gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.1)
*
* works with -DNO_SECOND or -x objective-c
*/
#import <Foundation/Foundation.h>
/*
* if defined, use only one argument
*/
#ifdef NO_SECOND
# define X(_)
#else
# define X(_) _
#endif
@interface Foo : NSObject
@end
@implementation Foo : NSObject
int a0, a1;
-(id)initWith: (int)a0_in X(: (int)a1_in) {
a0 = a0_in;
X(a1 = a1_in;)
return [super init];
}
-(int)a0 {return a0;}
X(-(int)a1 {return a1;})
@end
int main() {
int a0 = 0;
X(int a1 = 1;)
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
id bar = [Foo alloc];
bar = [bar initWith:a0 X(:a1)];
NSLog(@"%i", [bar a0]);
X(NSLog(@"%i", [bar a1]);)
[pool drain];
return 0;
}
The problem seems to be the message initWith sent to bar. The The compiler complains:
m.mm: In function ‘int main()’:
m.mm:46:27: error: found ‘:’ in nested-name-specifier, expected ‘::’
bar = [bar initWith:a0 X(:a1)];
^
m.mm:24:15: note: in definition of macro ‘X’
# define X(_) _
^
m.mm:46:22: warning: no ‘-initWith:’ method found
bar = [bar initWith:a0 X(:a1)];
^
m.mm:46:22: warning: (Messages without a matching method signature
m.mm:46:22: warning: will be assumed to return ‘id’ and accept
m.mm:46:22: warning: ‘...’ as arguments.)
m.mm:46:13: error: expected ‘,’ before ‘initWith’
bar = [bar initWith:a0 X(:a1)];
^
m.mm:46:13: error: ‘initWith’ was not declared in this scope
m.mm:46:21: error: expected ‘,’ before ‘:’ token
bar = [bar initWith:a0 X(:a1)];
^
m.mm:46:21: error: expected identifier before ‘:’ token
m.mm: In lambda function:
m.mm:46:32: error: expected ‘{’ before ‘;’ token
bar = [bar initWith:a0 X(:a1)];
^
m.mm: In function ‘int main()’:
m.mm:46:32: warning: lambda expressions only available with -std=c++11 or -std=gnu++11
m.mm:46:6: error: cannot convert ‘main()::<lambda()>’ to ‘objc_object*’ in assignment
bar = [bar initWith:a0 X(:a1)];
^
m.mm:43:8: warning: unused variable ‘a1’ [-Wunused-variable]
X(int a1 = 1;)
^
m.mm:24:15: note: in definition of macro ‘X’
# define X(_) _
^
Somehow the compiler thinks this is a C++ lambda. The code works fine however, if initWith has only one parameter (try this by using -DNO_SECOND).
Note that this code is accepted as Objective-C code: Compile with -x objective-c. Link with $(gnustep-config --base-libs). Run and read:
2016-08-05 10:59:36.251 m[21666] 0
2016-08-05 10:59:36.252 m[21666] 1
What am I doing wrong? Or is Objective-C++ broken and will not fix?
