Compile the source code pasted below with "-Os -Wuninitialized" using C++.  You should get the 
following warnings:

uninit.cpp: In function 'int foo()':
uninit.cpp:13: warning: 'range$begin' is used uninitialized in this function
uninit.cpp: In function 'int bar()':
uninit.cpp:21: warning: 'range$end' may be used uninitialized in this function

where the '.' has been secretly replaced by '$'.  This used to be a problem with C and ObjC in the past 
also, but appears fixed now.

============ uninit.cpp ==================
/* Contributed by Ziemowit Laski <zlaski@apple.com> */
/* Check that unused warnings triggered by the optimizer contain '.' rather than '$' in them.  */
/* { dg-do compile } */
/* { dg-options "-Os -Wuninitialized" } */

typedef struct Range {
   long begin, end;
} Range;

int foo(void) {
  Range range;

  while(range.begin != 0) { } /* { dg-warning ".range\\.begin. is used uninitialized in this function" } */

  return 0;
}

extern int baz(void);

int bar(void) {
  Range range;  /* { dg-warning ".range\\.end. may be used uninitialized in this function" } */
  
  do {
    if(baz()) range.end = 2;
  }
  while(range.end != 0);
  
  return 0;
}