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[Bug tree-optimization/80397] New: missing -Wformat-overflow with arguments of enum types


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80397

            Bug ID: 80397
           Summary: missing -Wformat-overflow with arguments of enum types
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: msebor at gcc dot gnu.org
  Target Milestone: ---

GCC issues a warning for the buffer overflow in the call to sprintf in function
f in the test case below but it fails to do the same thing for the equivalent
function g.  This is because the format_integer function that extracts the
range of the integral argument tests for the argument's type being INTEGER_TYPE
rather than using the INTEGRAL_TYPE_P() macro as it should be.

$ cat z.c && gcc -O2 -S -Wall -Wextra -Wpedantic z.c
char d[1];

enum E { e10 = 10, e99 = 99 };

int f (int i)
{
  if (i < e10 || e99 < i)
    i = e10;

  return __builtin_sprintf (d, "%i", i);   // warning (ok)
}

int g (enum E i)
{
  if (i < e10 || e99 < i)
    i = e10;

  return __builtin_sprintf (d, "%i", i);   // missing warning (bug)
}
z.c: In function ‘f’:
z.c:10:33: warning: ‘%i’ directive writing 2 bytes into a region of size 1
[-Wformat-overflow=]
   return __builtin_sprintf (d, "%i", i);   // warning (ok)
                                 ^~
z.c:10:32: note: directive argument in the range [10, 99]
   return __builtin_sprintf (d, "%i", i);   // warning (ok)
                                ^~~~
z.c:10:10: note: ‘__builtin_sprintf’ output 3 bytes into a destination of size
1
   return __builtin_sprintf (d, "%i", i);   // warning (ok)
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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