diff options
Diffstat (limited to 'libobjc')
| -rw-r--r-- | libobjc/nil_method.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/libobjc/nil_method.c b/libobjc/nil_method.c index 47201d69cc1..5e37c4d5dfb 100644 --- a/libobjc/nil_method.c +++ b/libobjc/nil_method.c @@ -29,10 +29,25 @@ Boston, MA 02111-1307, USA. */ #include "runtime.h" -/* nil_method is declared with variable arguments but the runtime calls it - in a way that does not setup the variable arguments correctly. Some Architectures - that have special arg calling conventions like x86-64 do need every function with - variable arguments called the correct way. */ +/* When the receiver of a method invocation is nil, the runtime + returns nil_method() as the method implementation. This function + will be casted to whatever function was supposed to be executed to + execute that method (that function will take an id, followed by a + SEL, followed by who knows what arguments, depends on the method), + and executed. + + For this reason, nil_method() should be a function which can be + called in place of any function taking an 'id' argument followed by + a 'SEL' argument, followed by zero, or one, or any number of + arguments (both a fixed number, or a variable number !). + + There is no "proper" implementation of such a nil_method function + in C, however in all existing implementations it does not matter + when extra arguments are present, so we can simply create a function + taking a receiver and a selector, and all other arguments will be + ignored. :-) +*/ + id nil_method (id receiver, SEL op __attribute__ ((__unused__))) { |