[gentoo-user] Strange GCC behavior
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Now see this:
nilesh@Linux ~ $ cat /tmp/foo.c
int func(int a = 1) {}
nilesh@Linux ~ $ gcc /tmp/foo.c
/tmp/foo.c:1:16: error: expected ‘;’, ‘,’ or ‘)’ before ‘=’ token
nilesh@Linux ~ $ g++ /tmp/foo.c
/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/../../../../lib64/crt1.o: In
function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
nilesh@Linux ~ $ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
nilesh@Linux ~ $ g++ -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
Why is this happening? O_o
--
Nilesh Govindarajan
http://nileshgr.com
Re: [gentoo-user] Strange GCC behavior
On Thu, Sep 29, 2011 at 1:27 PM, Nilesh Govindarajan
cont...@nileshgr.com wrote:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Now see this:
nilesh@Linux ~ $ cat /tmp/foo.c
int func(int a = 1) {}
nilesh@Linux ~ $ gcc /tmp/foo.c
/tmp/foo.c:1:16: error: expected ‘;’, ‘,’ or ‘)’ before ‘=’ token
nilesh@Linux ~ $ g++ /tmp/foo.c
/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/../../../../lib64/crt1.o: In
function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
nilesh@Linux ~ $ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
nilesh@Linux ~ $ g++ -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
Why is this happening? O_o
First guess, you need an int main() function, or you need to tell gcc
not to look for one.
--
:wq
Re: [gentoo-user] Strange GCC behavior
* Nilesh Govindarajan cont...@nileshgr.com [110929 13:33]:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
No they're not. C doesn't have default function arguments.
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Uh, no it's not.
Why is this happening? O_o
Because it's not correct C.
Todd
Re: [gentoo-user] Strange GCC behavior
On Thu 29 Sep 2011 11:10:00 PM IST, Michael Mol wrote:
On Thu, Sep 29, 2011 at 1:27 PM, Nilesh Govindarajan
cont...@nileshgr.com wrote:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Now see this:
nilesh@Linux ~ $ cat /tmp/foo.c
int func(int a = 1) {}
nilesh@Linux ~ $ gcc /tmp/foo.c
/tmp/foo.c:1:16: error: expected ‘;’, ‘,’ or ‘)’ before ‘=’ token
nilesh@Linux ~ $ g++ /tmp/foo.c
/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/../../../../lib64/crt1.o: In
function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
nilesh@Linux ~ $ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
nilesh@Linux ~ $ g++ -v
Using built-in specs.
COLLECT_GCC=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3/g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/4.5.3/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with:
/media/500GB/gentoo_portage/tmp/portage/sys-devel/gcc-4.5.3-r1/work/gcc-4.5.3/configure
--prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.5.3
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.3/include/g++-v4
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec
--disable-fixed-point --without-ppl --without-cloog --disable-lto
--enable-nls --without-included-gettext --with-system-zlib
--disable-werror --enable-secureplt --enable-multilib
--enable-libmudflap --disable-libssp --enable-libgomp --enable-cld
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.5.3/python
--enable-checking=release --disable-libgcj
--enable-languages=c,c++,fortran --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu
--with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.5.3-r1
p1.0, pie-0.4.5'
Thread model: posix
gcc version 4.5.3 (Gentoo 4.5.3-r1 p1.0, pie-0.4.5)
Why is this happening? O_o
First guess, you need an int main() function, or you need to tell gcc
not to look for one.
Syntax error doesn't depend on existence of main. I just posted this as
a snippet, I'd been working on one of my practical programs and
spotted this problem with a function I'd just made. And yeah, my
program had main().
--
Nilesh Govindarajan
http://nileshgr.com
Re: [gentoo-user] Strange GCC behavior
On Thu, Sep 29, 2011 at 1:43 PM, Todd Goodman t...@bonedaddy.net wrote:
* Nilesh Govindarajan cont...@nileshgr.com [110929 13:33]:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
No they're not. C doesn't have default function arguments.
That's another problem. (I don't know if gcc extends C to that end, though)
This may be useful once he gets there:
https://gustedt.wordpress.com/2010/06/03/default-arguments-for-c99/
--
:wq
Re: [gentoo-user] Strange GCC behavior
On Thu 29 Sep 2011 11:13:54 PM IST, Todd Goodman wrote:
* Nilesh Govindarajan cont...@nileshgr.com [110929 13:33]:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
No they're not. C doesn't have default function arguments.
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Uh, no it's not.
Why is this happening? O_o
Because it's not correct C.
Todd
Gah! so that's the reason. I've been coding C++ and other languages
with default arguments that I forgot C.
--
Nilesh Govindarajan
http://nileshgr.com
Re: [gentoo-user] Strange GCC behavior
On Thu, 29 Sep 2011 22:57:25 +0530, Nilesh Govindarajan wrote about
[gentoo-user] Strange GCC behavior:
Default function arguments in C are specified like this:
int func(int a = 10) {} // just a dummy function
Now I save that in a file called foo.c
The above piece of code is valid in C as well as C++
Not in C90. The default grammar does not permit default values for
arguments in C, only C++.
Why is this happening? O_o
Try adding -std=gnu99 as a compiler switch. That switches the grammar
from C90 to C99, with Gnu extensions too.
--
Regards,
Dave [RLU #314465]
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
dwn...@ntlworld.com (David W Noon)
*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
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