Google

Edit File: make.m4

# Check to see how 'make' treats includes.	            -*- Autoconf -*-

# Copyright (C) 2001-2020 Free Software Foundation, Inc.
#
# This file is free software; the Free Software Foundation
# gives unlimited permission to copy and/or distribute it,
# with or without modifications, as long as this notice is preserved.

# AM_MAKE_INCLUDE()
# -----------------
# Check whether make has an 'include' directive that can support all
# the idioms we need for our automatic dependency tracking code.
AC_DEFUN([AM_MAKE_INCLUDE],
[AC_MSG_CHECKING([whether ${MAKE-make} supports the include directive])
cat > confinc.mk << 'END'
am__doit:
	@echo this is the am__doit target >confinc.out
.PHONY: am__doit
END
am__include="#"
am__quote=
# BSD make does it like this.
echo '.include "confinc.mk" # ignored' > confmf.BSD
# Other make implementations (GNU, Solaris 10, AIX) do it like this.
echo 'include confinc.mk # ignored' > confmf.GNU
_am_result=no
for s in GNU BSD; do
  AM_RUN_LOG([${MAKE-make} -f confmf.$s && cat confinc.out])
  AS_CASE([$?:`cat confinc.out 2>/dev/null`],
      ['0:this is the am__doit target'],
      [AS_CASE([$s],
          [BSD], [am__include='.include' am__quote='"'],
          [am__include='include' am__quote=''])])
  if test "$am__include" != "#"; then
    _am_result="yes ($s style)"
    break
  fi
done
rm -f confinc.* confmf.*
AC_MSG_RESULT([${_am_result}])
AC_SUBST([am__include])])
AC_SUBST([am__quote])])