bug#65319: compilation error on Android (Termux)

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Bruno Haible <bruno@clisp.org> writes:

> Hi,
>
> Compiling a current Emacs checkout from today on Android, inside the Termux
> app, produces a compilation error:
>
> ../../src/dired.c:1140:16: warning: call to undeclared function 'getpwent'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
>   while ((pw = getpwent ()))
>                ^
> ../../src/dired.c:1140:14: error: incompatible integer to pointer conversion assigning to 'struct passwd *' from 'int' [-Wint-conversion]
>   while ((pw = getpwent ()))
>              ^ ~~~~~~~~~~~
>
> The reason is that the default Android API level in Termux is 24,
> the Android <pwd.h> declares getpwent() only starting with API level 26:
>
>   #if __ANDROID_API__ >= 26
>   struct passwd* getpwent(void) __INTRODUCED_IN(26);
>   ...
>
> yet HAVE_GETPWENT and HAVE_ENDPWENT come out as 1.
>
> I can see two possible fixes:
>   a) use
>        gl_CHECK_FUNCS_ANDROID([getpwent], [[#include <pwd.h>]])
>      instead of
>        AC_CHECK_FUNCS(... getpwent ...)
>      in configure.ac,
>   b) add
>        AC_CHECK_DECLS([getpwent], [], [], [[
>          #include <sys/types.h>
>          #include <pwd.h>
>          ]])
>      to configure.ac, and a '&& HAVE_DECL_GETPWENT' in
>      src/dired.c line 1137.
>
> Bruno

Thanks.  What does config.guess say in Termux?  And are you trying to
build the Android port on Android, or just Emacs itself?

P.S: our bug tracker intercepts all mail and resends individual messages
itself, so you must use the X-Debbugs-Cc header instead of the carbon
copy list when initially opening a bug.  If you don't, I get the message
you send to the bug tracker, instead of the message it resends.

Thanks.