On Sat, Mar 20, 2010 at 5:40 PM, Tadashi Koike <tadash...@gmail.com> wrote:
> Hi all,
> (* I am weak in English, so pleas forgive my English mistake.)
>
> Please teach me about a behavior of -save-temps=obj option
> on gcc 4.5. A behavior I found is whether bug or specification ?
>
> [ summary ]
> compiling is failed when more than two source file are
> specified with both -save-temps=obj and -o options.
>
> 1) Environment
> -------------------------------------------------------
> [System]: Fedora release 12 (Constantine)
> [gcc version]:
> % /usr/local/bin/gcc -v
> Using built-in specs.
> COLLECT_GCC=/usr/local/bin/gcc
>
> COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/lto-wrapper
> Target: x86_64-unknown-linux-gnu
> Configured with: ../gcc-4.5-20100304-src/configure
> --prefix=/usr/local --mandir=/usr/local/share/man
> --infodir=/usr/local/share/info --enable-languages=c,c++ --disable-nls
> Thread model: posix
> gcc version 4.5.0 20100304 (experimental) (GCC)
> -------------------------------------------------------
>
> 2) Source files I used are bellow:
> [main.c]
> +------------------------------------------------------
> |extern int func(const char *);
> |int main () {
> | func("hello world!\n");
> |}
> +------------------------------------------------------
> [func.c]
> +------------------------------------------------------
> |#include <stdio.h>
> |int func (const char *str) {
> | return(fprintf(stdout, str));
> |}
> +------------------------------------------------------
>
> 3) Files/Directory structure is bellow:
> /tmp/test/hellow.c
> /func.c
> /obj_dir/
>
> 4) Test operations.
> I tryed bellow operations at /tmp/test directory.
> -------------------------------------------------------
> [[ operations being successful ]]
> % gcc main.c func.c
> % gcc -o obj_dir/hello main.c func.c
> % gcc -save-temps=cwd main.c func.c
> % gcc -save-temps=cwd -o obj_dir/hello main.c func.c
> % gcc -save-temps=obj main.c func.c
>
> [[ operations being error ]]
> % gcc -save-temps=obj -o hellow main.c func.c
> % gcc -save-temps=obj -o obj_dir/hellow main.c func.c
>
> // example error messages //
> obj_dir/hello.o: In function `func':
> func.c:(.text+0x0): multiple definition of `func'
> obj_dir/hello.o:func.c:(.text+0x0): first defined here
> /usr/lib/../lib64/crt1.o: In function `_start':
> (.text+0x20): undefined reference to `main'
> collect2: ld returned 1 exit status
>
> // more information//
> * in this error case, temporary files are nemed as
> 'hello.i' and that content is from 'func.c', but
> contents of 'hello.s' is perhaps from 'main.c'.
> -------------------------------------------------------
>
> I think that two understanding are possible.
> A) this behavior is a specification like '-o' option with
> using -c option.
>
> [ operation example ]
> % gcc -c -o obj_dir/hello.o main.c func.c
> gcc: cannot specify -o with -c, -S or -E with multiple files
>
> B) this behavior is a bug.
> [ reason ]
> In below case, temporary files are made in current
> directory. names of these files are based on 'source
> file'.
>
> % gcc -save-temps=cwd -o obj_dir/hello main.c func.c
>
> When -save-temps=cwd option is exchanged to
> -save-temps=obj, I expect to keep names of temporary
> files as from 'source file', and only a place to save
> temporary files are exchanged to object directory.
>
> Because I don't understand that this behavior is whether
> bug or specification, so I don't report this to bugzilla
> yet.
>
> I feel that function of -save-temps=obj option is great!
> I would like to know how to use -save-temps=obj option.
> So pleas teach me true behavior about -save-temps=obj.
It should be an error to use -save-temps=obj with multiple
input files. Mike, can you look at this?
Thanks,
Richard.
> Best regards,
> Tadashi Koike
>
