[Bug objc/94637] New: @selector() broken for selectors containing repeated colons

["rfm at gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94637

            Bug ID: 94637
           Summary: @selector() broken for selectors containing repeated
                    colons
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: objc
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rfm at gnu dot org
  Target Milestone: ---

The compiler fails to compile legal Objective-C programs which use the
@selector() syntax to send message to objects, if those messages have multiple
parameters and the method does not describe each one.

eg. when given @selector(styleoffsets::::::) the compiler errors with the
message
 error: expected ‘)’ before ‘::’ token

Within @selector() each colon marks the position at which an argument would be
inserted in a method invocation (when a message is sent to an object).  It is
therefore not legal for the compiler to consider a pair of colons to be a token
in this context.

In the above example, the method declaration looks like this:

- (void) styleoffsets: (float*)l : (float*)r : (float*)t : (float*)b
                     : (unsigned int)style;

While imo it would be better coding style to describe parameters as part of the
method name, it's certainly correct/legal objective-c to have multiple
parameters each preceded only by a colon.

A trivial program to demonstrate the bug would be

#include <stdio.h>
#include <objc/objc.h>

int main()
{
  SEL   s = @selector(example::);
  printf("%s\n", sel_getName(s));
  return 0;
}


This program, if built with the command 'gcc program.m -lobjc' should produce
an a.out which just prints the selector name.