+dnl currently if you pass $LD=foo, merge objs command will be set to $(which foo)

+dnl which is not required by GHC and also wrong.

+BINDIST_DETERMINE_LINKER([$target],[GccUseLdOpt])

+dnl at this point, we should have set LD in all cases, so FIND_MERGE_OBJECTS command can

+dnl go off and do it's thing

+            cmd [Cwd $ root -/- bindist_folder] tarPath $

+                [ "-c"

+                , "-f" , compressorExtension compressor $ ghcVersionPretty <.> "tar"

+                , ghcVersionPretty ] <> compressorTarFlag compressor

+      phony (name <> "-dist-uncompressed") $ mk_bindist NoCompressor

+data Compressor = Gzip | Bzip2 | Xz | NoCompressor

+compressorTarFlag :: Compressor -> [String]

+compressorTarFlag Gzip  = ["--gzip"]

+compressorTarFlag Xz    = ["--xz"  ]

+compressorTarFlag Bzip2 = ["--bzip"]

+compressorTarFlag NoCompressor = []

+compressorExtension :: Compressor -> String -> String

+compressorExtension Gzip  p        = p <.> "gz"

+compressorExtension Xz    p        = p <.> "xz"

+compressorExtension Bzip2 p        = p <.> "bz2"

+compressorExtension NoCompressor p = p

+# BINDIST_DETERMINE_LINKER

+# ------------------------

+#

+# This is used to determine the linker within the bindists configure

+#

+# Notes:

+# - usually, linking works by invoking $CC

+# - objects are merged using $LD directly

+# - $LD is a configure variable and is meaningless to $CC

+# - gcc only knows linker *flavours*, it cannot use paths

+#   which means that the linker path should not be an absolute path

+# - clang konws --ld-path which means that it can be passed that

+#   flag and also merge objs can be an absolute path

+#

+# Algorithm:

+# if $LD is set

+#    then if $CC accepts --ld-path=$(which $LD)

+#            then set --ld-path=$(which $LD), MergeObjsCommand=$(which $LD)

+#            else if $CC accepts --fuse-ld=$LD ($LD is a linker flavour, not an absolute path)

+#                    then set -fuse-ld=$LD, MergeObjsCommand=$LD (not $(which ld))

+#                    else Reject with

+#                            "$LD is not compatible with $CC you chose. This means that $LD is either

+#                             an unsupported linker flavour or your $CC does not support absolute linker

+#                             paths"

+#    else if --disable-ld-override is set or $target is macos

+#            then if $CC accepts --ld-path=$(which ld)

+#                    then set --ld-path=$(which ld), set MergeObjsCommand=$(which ld)

+#                    else set *no* flag (equivalent to --fuse-ld=ld, if you will), set MergeObjsCommand=ld

+#            else if $CC accepts --ld-path=$(which ld.lld)

+#                    then set --ld-path=$(which ld.lld), MergeObjsCommand=$(which ld.lld)

+#                    else if $CC accepts -fuse-ld=lld

+#                            then set -fuse-ld=lld, MergeObjsCommand=ld.lld

+#                            else set *no* flag (equivalent to --fuse-ld=ld), set MergeObjsCommand=ld

+#

+# $1 = the platform

+# $2 = the variable to set with GHC options to configure gcc to use the chosen linker

+#

+AC_DEFUN([BINDIST_DETERMINE_LINKER],[

+    AC_ARG_ENABLE(ld-override,

+      [AS_HELP_STRING([--disable-ld-override],

+        [Prevent GHC from overriding the default linker used by gcc. If ld-override is enabled GHC will try to tell gcc to use whichever linker is selected by the LD environment variable. [default=override enabled]])],

+      [],

+      [enable_ld_override=yes])

+

+  AC_REQUIRE([AC_PROG_CC])

+  AC_REQUIRE([AC_CANONICAL_TARGET])

+

+  check_ld_path() {

+       AC_MSG_CHECKING([whether C compiler supports --ld-path=[$]1])

+       ld_path="[$]1"

+       echo 'int main(void) { return 0; }' > conftest.c

+       if $CC -o conftest.o "--ld-path=$ld_path" $LDFLAGS conftest.c > /dev/null 2>&1

+       then

+           AC_MSG_RESULT([yes])

+           ld_path_ok=yes

+       else

+           AC_MSG_RESULT([no])

+           ld_path_ok=no

+       fi

+       rm -f conftest.c conftest.o

+  }

+

+  check_fuse_ld() {

+    AC_MSG_CHECKING([whether C compiler supports -fuse-ld=[$]1])

+    ld="[$]1"

+    echo 'int main(void) {return 0;}' > conftest.c

+    if $CC -o conftest.o -fuse-ld=[$]1 $LDFLAGS conftest.c > /dev/null 2>&1

+    then

+        AC_MSG_RESULT([yes])

+        fuse_ld_ok=yes

+    else

+        AC_MSG_RESULT([no])

+        fuse_ld_ok=no

+    fi

+    rm -f conftest.c conftest.o

+  }

+

+  try_set_linker_to() {

+    AC_MSG_CHECKING([whether linker can be set to [$]1])

+    tmp_ld=[$]1

+    abs_path=`command -v "$tmp_ld" 2>/dev/null` # get absolute path of $tmp_ld if it isn't already one

+    ld_path_ok="no"

+    if test "z$abs_path" != "z" && check_ld_path "$abs_path" && test "x$ld_path_ok" = "xyes";

+       then $2="--ld-path=$abs_path"

+            AC_CHECK_TARGET_TOOL([LD], [$abs_path])

+            linker_set_successfully=yes

+       else # --ld-path does not work or $LD cannot be resolved to an absolute path

+            fuse_ld_ok=no

+            if check_fuse_ld "$tmp_ld"  && test "x$fuse_ld_ok" = "xyes";

+               then $2="-fuse-ld=$tmp_ld"

+                    AC_CHECK_TARGET_TOOL([LD], [$tmp_ld])

+                    linker_set_successfully=yes

+               else AC_MSG_WARN(["$tmp_ld could not be set via either '--ld-path' or '-fuse-ld"])

+                    linker_set_successfully=no

+            fi

+    fi

+  }

+

+  # we are lenient when $LD=ld and just act as if $LD wasn't set and 

+  # enable-ld-override is off

+  if test "z$LD" != "z" && test "z$LD" != "zld";

+     then linker_set_successfully=no

+          try_set_linker_to "$LD"

+          if test "z$linker_set_successfully" != "zyes";

+             then AC_MSG_FAILURE([ $tmp_ld is an invalid linker. If your C compiler accepts the '--ld-path' flag,

+                  \$LD can be either of an executable name that is in \$PATH *or* a path to an executable.

+                  If your C compiler only supports the '--fuse-ld' flag, \$LD can only be one of the linker flavours supported

+                  by it. Mind that if your C compiler supports '--ld-path', 'configure' will always prefer using an absolute path

+                  to your linker as that is less error-prone.])

+          fi

+

+     else # $LD is not set -- we will do the ld-override non-sense

+          if test "x$enable_ld_override" = "xyes" && test "z$LD" != "zld" && case "$1" in

+                    *-darwin) false ;; # don't do the ld override thing on macos

+                    *) true ;;

+                  esac;

+             then

+                  AC_MSG_NOTICE(["enable ld override was set and no more specific linker was chosen by setting \$LD, trying to find best possible linker"])

+                  try_set_linker_to "lld"

+                  if test "z$linker_set_successfully" != "zyes";

+                     then # ... bail out, just use ld in path

+                          $2=""

+                          AC_CHECK_TARGET_TOOL([LD], [ld])

+                  fi

+             else # ld override is not set and $LD not set either

+                  $2=""

+                  AC_CHECK_TARGET_TOOL([LD], [ld])

+          fi

+  fi

+

+  AC_MSG_NOTICE([linker discovery set $2 set to $$2])

+

+  CHECK_LD_COPY_BUG([$1])

+])