[cfe-dev] uninitialized variable warning, etc

[rdogra at earthlink.net]

given following code:
~/clang-test-> cat test.c

#include <stdio.h>

int main (void)  {
  int a = 0,  b;

  a = b + a;
  printf ("a = %s", a);
  return 0;
}


/clang-test-> gcc -Wall -Wno-switch -Wdisabled-optimization -Wpointer- 
arith -Wredundant-decls -Wno-pointer-sign -Wcast-qual -Wwrite-strings - 
O3 -fno-math-errno -std=c99 test.c
test.c: In function ‘main’:
test.c:8: warning: format ‘%s’ expects type ‘char *’, but argument 2  
has type ‘int’
test.c:7: warning: ‘b’ is used uninitialized in this function

~/clang-test-> ccc -Wall -Wno-switch -Wdisabled-optimization -Wpointer- 
arith -Wredundant-decls -Wno-pointer-sign -Wcast-qual -Wwrite-strings - 
O3 -fno-math-errno -std=c99 test.c

~/clang-test-> gcc -Wall -std=c99 test.c test.c: In function ‘main’:
test.c:8: warning: format ‘%s’ expects type ‘char *’, but argument 2  
has type ‘int’

~/clang-test-> gcc -Wall  -O3 test.c
test.c: In function ‘main’:
test.c:8: warning: format ‘%s’ expects type ‘char *’, but argument 2  
has type ‘int’
test.c:7: warning: ‘b’ is used uninitialized in this function

~/clang-test-> ccc -Wall -O3 -std=c99 test.c
~/clang-test->



Also clang warns on the following but gcc doesn't??
libavcodec/dsputil.c:177:8: warning: use of unary operator that may be  
intended as compound assignment (-=)
    end=-1;
       ^~
libavcodec/dsputil.c:3966:10: warning: use of unary operator that may  
be intended as compound assignment (-=)
    for(i=-len, j=len-1; i<0; i++, j--) {
         ^~