These macros check for particular programs--whether they exist, and in some cases whether they support certain features.
YYTEXT_POINTER if yytext is a `char *' instead
of a `char []'. Also set output variable LEX_OUTPUT_ROOT to
the base of the file name that the lexer generates; usually
`lex.yy', but sometimes something else. These results vary
according to whether lex or flex is being used.
mawk, gawk, nawk, and awk, in that
order, and set output variable AWK to the first one that it
finds. It tries mawk first because that is reported to be the
fastest implementation.
CC is not already set in the
environment, check for gcc, and use cc if that's not found.
Set output variable CC to the name of the compiler found.
If using the GNU C compiler, set shell variable GCC to
`yes', empty otherwise. If output variable CFLAGS was
not already set, set it to `-g -O2' for the GNU C compiler
(`-O2' on systems where GCC does not accept `-g'), or `-g'
for other compilers.
If the C compiler being used does not produce executables that can run
on the system where configure is being run, set the shell
variable cross_compiling to `yes', otherwise `no'.
In other words, this tests whether the build system type is different
from the host system type (the target system type is irrelevant to this
test). See section Manual Configuration, for more on support for cross compiling.
NO_MINUS_C_MINUS_O.
CPP to a command that runs the
C preprocessor. If `$CC -E' doesn't work, it uses `/lib/cpp'.
It is only portable to run CPP on files with a `.c'
extension.
If the current language is C (see section Language Choice), many of the
specific test macros use the value of CPP indirectly by calling
AC_TRY_CPP, AC_CHECK_HEADER, AC_EGREP_HEADER, or
AC_EGREP_CPP.
CXX or CCC (in that order) is set; if so, set output
variable CXX to its value. Otherwise search for a C++ compiler
under likely names (c++, g++, gcc, CC,
cxx, and cc++). If none of those checks succeed, as a
last resort set CXX to gcc.
If using the GNU C++ compiler, set shell variable GXX to
`yes', empty otherwise. If output variable CXXFLAGS was
not already set, set it to `-g -O2' for the GNU C++ compiler
(`-O2' on systems where G++ does not accept `-g'), or `-g'
for other compilers.
If the C++ compiler being used does not produce executables that can run
on the system where configure is being run, set the shell
variable cross_compiling to `yes', otherwise `no'.
In other words, this tests whether the build system type is different
from the host system type (the target system type is irrelevant to this
test). See section Manual Configuration, for more on support for cross compiling.
CXXCPP to a command that runs the
C++ preprocessor. If `$CXX -E' doesn't work, it uses `/lib/cpp'.
It is only portable to run CXXCPP on files with a `.c',
`.C', or `.cc' extension.
If the current language is C++ (see section Language Choice), many of the
specific test macros use the value of CXXCPP indirectly by
calling AC_TRY_CPP, AC_CHECK_HEADER,
AC_EGREP_HEADER, or AC_EGREP_CPP.
F77 is not already
set in the environment, check for g77, f77 and f2c,
in that order. Set the output variable F77 to the name of the
compiler found.
If using g77 (the GNU Fortran 77 compiler), then
AC_PROG_F77 will set the shell variable G77 to `yes',
and empty otherwise. If the output variable FFLAGS was not
already set in the environment, then set it to `-g -02' for
g77 (or `-O2' where g77 does not accept `-g').
Otherwise, set FFLAGS to `-g' for all other Fortran 77
compilers.
F77_NO_MINUS_C_MINUS_O if it
does not.
CC if using the
GNU C compiler and ioctl does not work properly without
`-traditional'. That usually happens when the fixed header files
have not been installed on an old system. Since recent versions of the
GNU C compiler fix the header files automatically when installed, this
is becoming a less prevalent problem.
INSTALL to the path of a BSD compatible
install program, if one is found in the current PATH.
Otherwise, set INSTALL to `dir/install-sh -c',
checking the directories specified to AC_CONFIG_AUX_DIR (or its
default directories) to determine dir (see section Creating Output Files). Also set
the variables INSTALL_PROGRAM and INSTALL_SCRIPT to
`${INSTALL}' and INSTALL_DATA to `${INSTALL} -m 644'.
This macro screens out various instances of install known to not
work. It prefers to find a C program rather than a shell script, for
speed. Instead of `install-sh', it can also use `install.sh',
but that name is obsolete because some make programs have a rule
that creates `install' from it if there is no `Makefile'.
A copy of `install-sh' which you may use comes with Autoconf. If
you use AC_PROG_INSTALL, you must include either
`install-sh' or `install.sh' in your distribution, or
configure will produce an error message saying it can't find
them--even if the system you're on has a good install program.
This check is a safety measure to prevent you from accidentally leaving
that file out, which would prevent your package from installing on
systems that don't have a BSD-compatible install program.
If you need to use your own installation program because it has
features not found in standard install programs, there is no
reason to use AC_PROG_INSTALL; just put the pathname of your
program into your `Makefile.in' files.
flex is found, set output variable LEX to
`flex' and LEXLIB to `-lfl', if that library is in a
standard place. Otherwise set LEX to `lex' and
LEXLIB to `-ll'.
LN_S to `ln -s', otherwise set it to `ln'.
If the link is put in a directory other than the current directory, its
meaning depends on whether `ln' or `ln -s' is used. To safely
create links using `$(LN_S)', either find out which form is used
and adjust the arguments, or always invoke ln in the directory
where the link is to be created.
In other words, it does not work to do
$(LN_S) foo /x/bar
Instead, do
(cd /x && $(LN_S) foo bar)
RANLIB to `ranlib' if ranlib
is found, otherwise to `:' (do nothing).
bison is found, set output variable YACC to
`bison -y'. Otherwise, if byacc is found, set YACC
to `byacc'. Otherwise set YACC to `yacc'.
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