[LLVMbugs] [Bug 5984] New: Bogus 'use of undeclared identifier' error causing compilation to fail

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=5984

           Summary: Bogus 'use of undeclared identifier' error causing
                    compilation to fail
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: parser
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: richard at tiptree.demon.co.uk
                CC: llvmbugs at cs.uiuc.edu


Created an attachment (id=4019)
 --> (http://llvm.org/bugs/attachment.cgi?id=4019)
sys/wait.h header from centos-5.4 with glibc-2.11.1 built from source

When compiling the gnustep-base library (objective-c ) I encountered
compilation failure related to sys/wait.h
It appears that something about the wait definitions causes clang to lose track
of the visibility of the objective-c class instance variable being used.
I simplified this to a tiny test program:

#include <sys/wait.h>
#include <objc/Object.h>

@interface      MyClass : Object
{
  int myStatus;
}
- (int) test;
@end

@implementation MyClass
- (int) test
{
  if (WIFEXITED(myStatus))
    return 1;
  return 0;
}
@end

int
main()
{
}


When I compile this test using clang (and a -I option to tell it where my
objective-c headers are) I get the following:

clang a.m -I /usr/GNUstep/Local/Library/Headers -lobjc
a.m:14:7: error: use of undeclared identifier 'myStatus'
  if (WIFEXITED(myStatus))
      ^
In file included from a.m:1:
/usr/include/sys/wait.h:85:28: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                ^
In file included from a.m:1:
In file included from /usr/include/sys/wait.h:80:
/usr/include/bits/waitstatus.h:38:30: note: instantiated from:
#define __WIFEXITED(status)     (__WTERMSIG(status) == 0)
                                 ^
a.m:14:7: note: instantiated from:
  if (WIFEXITED(myStatus))
      ^
In file included from a.m:1:
/usr/include/sys/wait.h:85:28: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                ^
a.m:14:7: note: instantiated from:
  if (WIFEXITED(myStatus))
      ^
In file included from a.m:1:
/usr/include/sys/wait.h:85:41: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                             ^
a.m:14:7: note: instantiated from:
  if (WIFEXITED(myStatus))
      ^
a.m:14:17: note: instantiated from:
  if (WIFEXITED(myStatus))
                ^
a.m:14:7: error: member reference base type 'void' is not a structure or union
  if (WIFEXITED(myStatus))
      ^~~~~~~~~~~~~~~~~~~
In file included from a.m:1:
/usr/include/sys/wait.h:85:28: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                ^
In file included from a.m:1:
In file included from /usr/include/sys/wait.h:80:
/usr/include/bits/waitstatus.h:38:30: note: instantiated from:
#define __WIFEXITED(status)     (__WTERMSIG(status) == 0)
                                 ^
a.m:14:7: note: instantiated from:
  if (WIFEXITED(myStatus))
      ^
In file included from a.m:1:
/usr/include/sys/wait.h:85:28: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                ^
a.m:14:7: note: instantiated from:
  if (WIFEXITED(myStatus))
      ^
In file included from a.m:1:
/usr/include/sys/wait.h:85:41: note: instantiated from:
# define WIFEXITED(status)      __WIFEXITED (__WAIT_INT (status))
                                             ^
/usr/include/sys/wait.h:48:42: note: instantiated from:
                   { .__in = (status) }).__i))
                   ~~~~~~~~~~~~~~~~~~~~~ ^
2 diagnostics generated.




As you can see, the compiler appears to have forgotten about the myStatus
instance variable.

An easy workaround is to copy myStatus to a local integer variable, and use
that copy as the argument to WIFEXITED, so this bug is annoying, but not
critical.

I attach a copy of the sys/wait.h file involved.


-- 
Configure bugmail: http://llvm.org/bugs/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.