Hello,
I would like to report about two (probably, self-connected) bugs in the
__typeof__ C function.
These bugs are reproduced when I am trying to compile a simple code with
XLC compiler on AIX 5.2. Please, look at the code snippets below.
1. typeof_example_1.c
long Func(int x) { return x; }
int main()
{
int y, z = 1;
y = (__typeof__(Func(z)))0;
return 0;
}
cc_r typeof_example_1.c
"typeof_example_1.c", line 5.26: 1506-045 (S) Undeclared identifier z.
The 'z' variable is obviously defined, so "Undeclared identifier" message
is wrong.
2. typeof_example_2.c (fails on 64bit compilation only)
long Func(int x) { return x; }
int main()
{
int y, z = 1;
y = (__typeof__(Func((__typeof__(z))z)))0;
return 0;
}
cc_r -q64 typeof_example_2.c
"typeof_example_2.c", line 5.21: 1506-343 (S) Redeclaration of Func differs
from previous declaration on line 1 of "typeof_example_2.c".
"typeof_example_2.c", line 5.21: 1506-050 (I) Return type "int" in
redeclaration is not compatible with the previous return type "long".
Here the compiler erroneously considers the line as a function declaration,
but is is a call and not a declaration. This works although for 32bit
compilation.
Both code snippets work with GCC compiler in both 32-bit and 64bit modes.
What is interesting, we use cc_r, but not xlc binary in our build system
(it is probably due to historical reasons and persons who can answer me why
exactly cc_r have gone many years ago). But with xlc both code snippets
also fail, however with other error messages (no matter, 32 or 64bit).
xlc typeof_example_1.c
"typeof_example_1.c", line 5.30: 1506-275 (S) Unexpected text integer
constant encountered.
xlc typeof_example_2.c
"typeof_example_2.c", line 5.41: 1506-275 (S) Unexpected text z encountered.
"typeof_example_2.c", line 5.45: 1506-275 (S) Unexpected text integer
constant encountered.
Environment:
uname -a
AIX pavo 2 5 00C9E74E4C00
which cc_r
/usr/vac/bin/cc_r
which xlc
/usr/vac/bin/xlc
ls /usr/vac/bin/
CreateExportList cc128 cc_r4 cleanpdf
xlc128 xlc_r4
c89 cc128_r cc_r7 resetpdf
xlc128_r xlc_r7
cc cc_r cforaixhelp xlc
xlc_r
Use case:
These issues were discovered at attempt to build FreeType 2.7.0 with XLC
compiler.
The link to the FreeType issue: http://savannah.nongnu.org/bugs/?49448.
I have contacted FreeType developers and got a feedback that TYPEOF
implementation is taken from gnulib's intprops.h, that is why my question
is addressed to gnu.org mail list.
I do understand that the OS AIX 5.2 is legacy and the best way is to
migrate to a newer one, but we cannot do it right now because customers
request builds for this OS.
I would be happy if you could give some clue why __typeof__ works
completely differently for XLC.
Thanks in advance!
--
Best Regards,
Alexander Samoilov,
Build & Integration Ingenieur,
Compart AG (Böblingen, Germany)
