[gnutls-devel] libtasn1 | Cross compilation issue (#28)

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Roman Bolshakov commented:


I'm not sure if the issue is fixed. I can reproduce if libtasn1 is compiled with -O1.
Neither libgnu.a nor c-ctype.o have symbol of `c_isdigit`:
```
$ nm lib/gl/.libs/libgnu.a

lib/gl/.libs/libgnu.a(c-ctype.o):
0000000000000000 t ltmp0

lib/gl/.libs/libgnu.a(strverscmp.o):
0000000000000000 T _strverscmp
00000000000000ec s _strverscmp.next_state
00000000000000f8 s _strverscmp.result_type
0000000000000000 t ltmp0
00000000000000ec s ltmp1
0000000000000120 s ltmp2
$ nm lib/gl/c-ctype.o
0000000000000000 t ltmp0
```

If c-ctype.c is compiled with -E flag we can see that `c_isdigit` is declared as `static __attribute__ ((__unused__))`:
```
static __attribute__ ((__unused__)) _Bool
c_isdigit (int c)
{
  switch (c)
    {
    case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
      return 1;
    default:
      return 0;
    }
}
```

The function is static and compiler doesn't see if it's used so it optimizes it out and that's why the symbol is not available in c-ctype.o.
If we look closer how `c_isdigit` is defined we can notice it's defined with `C_CTYPE_INLINE`:
```
C_CTYPE_INLINE bool
c_isdigit (int c)
{
  switch (c)
    {
    _C_CTYPE_DIGIT:
      return true;
    default:
      return false;
    }
}
```

The symbol is assigned to `_GL_EXTERN_INLINE` in c-ctype.c:
```
#include <config.h>
#define C_CTYPE_INLINE _GL_EXTERN_INLINE
#include "c-ctype.h"
```

_GL_EXTERN_INLINE is supposed to be [portable "extern inline"](https://www.gnu.org/software/gnulib/manual/html_node/extern-inline.html) but it doesn't seem to work as intended on modern macOS. I think the issue is caused by incorrect _GL_EXTERN_INLINE definition inside gnulib.

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