http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57627
Bug ID: 57627
Summary: -Wsizeof-pointer-memaccess should make an exception
for character types
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: harald at gigawatt dot nl
$ cat test.c
void f1(int *dst, int *src)
{ __builtin_memcpy(dst, src, sizeof(int *)); }
void f2(char *dst, char *src)
{ __builtin_memcpy(dst, src, sizeof(char *)); }
void f3(unsigned char *dst, unsigned char *src)
{ __builtin_memcpy(dst, src, sizeof(unsigned char *)); }
$ gcc -c test.c -Wall
test.c: In function ‘f1’:
test.c:2:36: warning: argument to ‘sizeof’ in ‘__builtin_memcpy’ call is the
same pointer type ‘int *’ as the destination; expected ‘int’ or an explicit
length [-Wsizeof-pointer-memaccess]
{ __builtin_memcpy(dst, src, sizeof(int *)); }
^
test.c: In function ‘f2’:
test.c:5:36: warning: argument to ‘sizeof’ in ‘__builtin_memcpy’ call is the
same pointer type ‘char *’ as the destination; expected ‘char’ or an explicit
length [-Wsizeof-pointer-memaccess]
{ __builtin_memcpy(dst, src, sizeof(char *)); }
^
test.c: In function ‘f3’:
test.c:8:36: warning: argument to ‘sizeof’ in ‘__builtin_memcpy’ call is the
same pointer type ‘unsigned char *’ as the destination; expected ‘unsigned
char’ or an explicit length [-Wsizeof-pointer-memaccess]
{ __builtin_memcpy(dst, src, sizeof(unsigned char *)); }
^
$ gcc --version
gcc (GCC) 4.8.1 20130603 (Red Hat 4.8.1-1)
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
The warning makes sense for most types (f1), but for character types, I don't
think GCC should give any warning (f2 and f3). I'm seeing this warning for
correct code that stores pointers in raw byte buffers, and I would be surprised
if that is less common than code that really means to memcpy a single byte.
