Re: libtool & GCC 3.0

[Robert Boehne]

Steve:

The patch looks fine to me, does anyone else object to it?
I would really like to know why anyone would declare main() as
returning char, but there must have been some reason for it, right?
Anybody know of such a reason? I'd like to hear it.

Robert


Steve Ellcey wrote:
> 
> I was testing libtool with GCC 3.0 and ran into a configuration problem.
> I finally tracked it down to a problem with declaring main to be of type
> "char", older GCC's allowed this, GCC 3.0 does not.
> 
> At around line 3928 of configure a C++ program is generated that
> contains a table with symbol names extracted from another program.  Here
> is the program that my configure run generated:
> 
>         #ifdef __cplusplus
>         extern "C" {
>         #endif
> 
>         extern char nm_test_var;
>         extern char main();
>         extern char nm_test_func();
>         #if defined (__STDC__) && __STDC__
>         # define lt_ptr_t void *
>         #else
>         # define lt_ptr_t char *
>         # define const
>         #endif
> 
>         /* The mapping between symbol names and symbols. */
>         const struct {
>           const char *name;
>           lt_ptr_t address;
>         }
>         lt_preloaded_symbols[] =
>         {
>           {"nm_test_var", (lt_ptr_t) &nm_test_var},
>           {"main", (lt_ptr_t) &main},
>           {"nm_test_func", (lt_ptr_t) &nm_test_func},
>           {0, (lt_ptr_t) 0}
>         };
> 
>         #ifdef __cplusplus
>         }
>         #endif
> 
> When this program is compiled with g++ 3.0 I get the following:
> 
> [hpsje] $ g++ -c conftest.cc
> conftest.cc:6: `main' must return `int'
> 
> And g++ returns an exit code of 1.
> 
> This messes up the rest of my configure/build resulting in a bad
> libtool.  This can be fixed by modifying
> lt_cv_sys_global_symbol_to_cdecl to declare things to be "int" instead
> of "char".  Does that sound like the right fix?
> 
> Here is a patch that can be used, if people think this is the right
> fix, I do not have write permission to CVS:
> 
> 2001-07-25  Steve Ellcey  <address@hidden>
> 
>         * libtool.m4 (lt_cv_sys_global_symbol_to_cdecl):  Change it from
>         "extern char" to "extern int" so that GCC 3.0 won't complain and
>         refuse to compile programs containing "extern char main()".
> 
> *** libtool.m4.orig     Wed Jul 25 10:54:14 2001
> --- libtool.m4  Wed Jul 25 10:37:05 2001
> *************** AC_CACHE_VAL([lt_cv_sys_global_symbol_pi
> *** 3583,3589 ****
>   symxfrm='\1 \2\3 \3'
> 
>   # Transform an extracted symbol line into a proper C declaration
> ! lt_cv_sys_global_symbol_to_cdecl="sed -n -e 's/^. .* \(.*\)$/extern char 
> \1;/p'"
> 
>   # Transform an extracted symbol line into symbol name and symbol address
>   lt_cv_sys_global_symbol_to_c_name_address="sed -n -e 's/^: \([[^ ]]*\) $/  
> {\\\"\1\\\", (lt_ptr) 0},/p' -e 's/^$symcode \([[^ ]]*\) \([[^ ]]*\)$/  
> {\"\2\", (lt_ptr) \&\2},/p'"
> --- 3583,3589 ----
>   symxfrm='\1 \2\3 \3'
> 
>   # Transform an extracted symbol line into a proper C declaration
> ! lt_cv_sys_global_symbol_to_cdecl="sed -n -e 's/^. .* \(.*\)$/extern int 
> \1;/p'"
> 
>   # Transform an extracted symbol line into symbol name and symbol address
>   lt_cv_sys_global_symbol_to_c_name_address="sed -n -e 's/^: \([[^ ]]*\) $/  
> {\\\"\1\\\", (lt_ptr) 0},/p' -e 's/^$symcode \([[^ ]]*\) \([[^ ]]*\)$/  
> {\"\2\", (lt_ptr) \&\2},/p'"
> *************** cygwin* | mingw* | pw32*)
> *** 3597,3603 ****
>     [symcode='[ABCDGISTW]']
>     ;;
>   hpux*) # Its linker distinguishes data from code symbols
> !   lt_cv_sys_global_symbol_to_cdecl="sed -n -e 's/^T .* \(.*\)$/extern char 
> \1();/p' -e 's/^$symcode* .* \(.*\)$/extern char \1;/p'"
>     lt_cv_sys_global_symbol_to_c_name_address="sed -n -e 's/^: \([[^ ]]*\) $/ 
>  {\\\"\1\\\", (lt_ptr) 0},/p' -e 's/^$symcode* \([[^ ]]*\) \([[^ ]]*\)$/  
> {\"\2\", (lt_ptr) \&\2},/p'"
>     ;;
>   irix*)
> --- 3597,3603 ----
>     [symcode='[ABCDGISTW]']
>     ;;
>   hpux*) # Its linker distinguishes data from code symbols
> !   lt_cv_sys_global_symbol_to_cdecl="sed -n -e 's/^T .* \(.*\)$/extern int 
> \1();/p' -e 's/^$symcode* .* \(.*\)$/extern int \1;/p'"
>     lt_cv_sys_global_symbol_to_c_name_address="sed -n -e 's/^: \([[^ ]]*\) $/ 
>  {\\\"\1\\\", (lt_ptr) 0},/p' -e 's/^$symcode* \([[^ ]]*\) \([[^ ]]*\)$/  
> {\"\2\", (lt_ptr) \&\2},/p'"
>     ;;
>   irix*)
> 
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-- 
Robert Boehne             Software Engineer
Ricardo Software   Chicago Technical Center
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