Possible bug - AC_PROG_CC

[Michael Ambrus]

It seems that AC_PROG_CC misbehaves if used inside a if-case, in which it
doesn't detects whether or not we try to use a cross compiler (and
$cross_compiling is not set to "yes"). In the example below, $USECPLUSPLUS
is "no" in both cases which is intentional.

   #AC_PROG_CC
   if test $USECPLUSPLUS != no; then
       dnl Tries to use g++ as instructed. Should fall back on gcc if c++
is not available
       AC_PROG_CXX
       AC_PROG_CC(g++)
       AC_LANG_CPLUSPLUS
       dnl The TK_CPLUSPLUS macro in config.h will be set accordingly to
the result
       AC_DEFINE_UNQUOTED([ESC_CPLUSPLUS],$GXX)
   else
       dnl Use gcc
       AC_PROG_CC
       AC_PROG_CC(gcc)
       AC_LANG_C
   fi

Case 1)
Verbatin as above the output will be the following:
...
install-sh exists... good!
checking for powerpc-eabisim-gcc... powerpc-eabisim-gcc
checking whether we are using the GNU C compiler... no
checking whether powerpc-eabisim-gcc accepts -g... no
checking for powerpc-eabisim-gcc option to accept ANSI C... none needed
checking for powerpc-eabisim-gcc... (cached) powerpc-eabisim-gcc
checking whether we are using the GNU C compiler... (cached) no
checking whether powerpc-eabisim-gcc accepts -g... (cached) no
checking for powerpc-eabisim-gcc option to accept ANSI C... (cached) none
needed
checking build system type... i686-pc-linux-gnu
checking host system type... powerpc-unknown-eabisim
checking target system type... powerpc-unknown-eabisim
configure: Build system CPU: i686
...

Case 2)
If the remark is removed (i.e. AC_PROG_CC is tested outside of the if-case),
It works OK:

...
install-sh exists... good!
checking for powerpc-eabisim-gcc... powerpc-eabisim-gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... yes
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether powerpc-eabisim-gcc accepts -g... yes
checking for powerpc-eabisim-gcc option to accept ANSI C... none needed
checking for powerpc-eabisim-gcc... (cached) powerpc-eabisim-gcc
checking whether we are using the GNU C compiler... (cached) yes
checking whether powerpc-eabisim-gcc accepts -g... (cached) yes
checking for powerpc-eabisim-gcc option to accept ANSI C... (cached) none
needed
checking for powerpc-eabisim-gcc... (cached) powerpc-eabisim-gcc
checking whether we are using the GNU C compiler... (cached) yes
checking whether powerpc-eabisim-gcc accepts -g... (cached) yes
checking for powerpc-eabisim-gcc option to accept ANSI C... (cached) none
needed
checking build system type... i686-pc-linux-gnu
...

The script containing the example above was called as follows: ./configure
--host=powerpc-eabisim

I'm not certain which version of autoconf is used since both autoconf2.13and
autoconf2.50 are installed on my system.

configure.in contains AC_PREREQ([2.59]), but if I try to set this to 2.13 I
get all sorts of other errors. Setting it to 2.50 produces the same as
mentioned above.

'autoconf -V' will respond 2.50 however...

Regards
/Michael