+# Extra autoconf macros for the Glasgow fptools
+#
+# To be a good autoconf citizen, names of local macros have prefixed with FP_ to
+# ensure we don't clash with any pre-supplied autoconf ones.
+
+
+# FP_EVAL_STDERR(COMMAND)
+# -----------------------
+# Eval COMMAND, save its stderr (without lines resulting from shell tracing)
+# into the file conftest.err and the exit status in the variable fp_status.
+AC_DEFUN([FP_EVAL_STDERR],
+[{ (eval $1) 2>conftest.er1
+ fp_status=$?
+ grep -v '^ *+' conftest.er1 >conftest.err
+ rm -f conftest.er1
+ (exit $fp_status); }[]dnl
+])# FP_EVAL_STDERR
+
+
+# FP_CHECK_FLAG(FLAG, [ACTION-IF-SUPPORTED], [ACTION-IF-NOT-SUPPORTED])
+# ---------------------------------------------------------------------
+# Check to see whether the compiler for the current language supports a
+# particular option.
+#
+# Implementation note: When given an unkown option, GCC issues an warning on
+# stderr only, but returns an exit value of 0 nevertheless. Consequently we have
+# to check stderr *and* the exit value.
+#
+# Used by ghc.
+AC_DEFUN(FP_CHECK_FLAG,
+[AC_LANG_COMPILER_REQUIRE()dnl
+AC_LANG_CASE([C], [fp_compiler="$CC" m4_pushdef([fp_Flags], [CFLAGS])],
+ [C++], [fp_compiler="$CXX" m4_pushdef([fp_Flags], [CXXFLAGS])],
+ [Fortran 77], [fp_compiler="$F77" m4_pushdef([fp_Flags], [FFLAGS])])
+m4_pushdef([fp_Cache], [fp_cv_[]fp_Flags[]AS_TR_SH([$1])])[]dnl
+AC_CACHE_CHECK([whether $fp_compiler accepts $1], [fp_Cache],
+[AC_LANG_CONFTEST([AC_LANG_PROGRAM()])
+fp_save_flags="$fp_Flags"
+fp_Flags="$fp_Flags $1"
+fp_Cache=no
+if FP_EVAL_STDERR([$ac_compile conftest.$ac_ext]) >/dev/null; then
+ test -s conftest.err || fp_Cache=yes
+fi
+fp_Flags="$fp_save_flags"
+rm -f conftest.err conftest.$ac_ext])
+AS_IF([test $fp_Cache = yes], [$2], [$3])[]dnl
+m4_popdef([fp_Cache])[]dnl
+m4_popdef([fp_Flags])[]dnl
+])# FP_CHECK_FLAG