+tryflag CFLAGS_AUTO -Wno-pointer-to-int-cast
+fi
+
+if test "x$visibility" = xauto ; then
+# This test checks toolchain support for several things:
+# - the -include option
+# - the attributes/pragmas used in vis.h
+# - linking code that takes the address of protected symbols
+# - gcc 3.x bug that wrongly claims declarations mismatch
+printf "checking whether global visibility preinclude works... "
+cat > "$tmpc" <<EOF
+__attribute__((__visibility__("default")))
+extern struct a *const x;
+typedef struct a b;
+extern b *const x;
+b *const x;
+int (*fp)(void);
+int foo(void) { }
+int bar(void) { fp = foo; return foo(); }
+EOF
+if $CC $CFLAGS_C99FSE $CPPFLAGS $CFLAGS \
+ -DSHARED -fPIC -I$srcdir/src/internal -include vis.h \
+ -nostdlib -shared -Wl,-Bsymbolic-functions \
+ -o /dev/null "$tmpc" >/dev/null 2>&1 ; then
+visibility=yes
+else
+visibility=no
+fi
+printf "%s\n" "$visibility"
+fi
+
+if test "x$visibility" = xyes ; then
+CFLAGS_AUTO="$CFLAGS_AUTO -include vis.h"
+CFLAGS_AUTO="${CFLAGS_AUTO# }"
+fi
+
+# Reduce space lost to padding for alignment purposes by sorting data
+# objects according to their alignment reqirements. This approximates
+# optimal packing.
+tryldflag LDFLAGS_AUTO -Wl,--sort-section,alignment
+tryldflag LDFLAGS_AUTO -Wl,--sort-common
+
+# When linking shared library, drop dummy weak definitions that were
+# replaced by strong definitions from other translation units.
+tryldflag LDFLAGS_AUTO -Wl,--gc-sections
+
+# Some patched GCC builds have these defaults messed up...
+tryldflag LDFLAGS_AUTO -Wl,--hash-style=both
+
+# Prevent linking if there are undefined symbols; if any exist,
+# libc.so will crash at runtime during relocation processing.
+# The common way this can happen is failure to link the compiler
+# runtime library; implementation error is also a possibility.
+tryldflag LDFLAGS_AUTO -Wl,--no-undefined
+
+# Avoid exporting symbols from compiler runtime libraries. They
+# should be hidden anyway, but some toolchains including old gcc
+# versions built without shared library support and pcc are broken.
+tryldflag LDFLAGS_AUTO -Wl,--exclude-libs=ALL
+
+test "$shared" = "no" || {
+# Disable dynamic linking if ld is broken and can't do -Bsymbolic-functions
+LDFLAGS_DUMMY=
+tryldflag LDFLAGS_DUMMY -Wl,-Bsymbolic-functions || {
+test "$shared" = "yes" && fail "$0: error: linker cannot build shared library"
+printf "warning: disabling dynamic linking support\n"
+shared=no
+}
+}
+
+# Find compiler runtime library
+test -z "$LIBCC" && tryldflag LIBCC -lgcc && tryldflag LIBCC -lgcc_eh
+test -z "$LIBCC" && tryldflag LIBCC -lcompiler_rt
+test -z "$LIBCC" && try_libcc=`$CC -print-file-name=libpcc.a 2>/dev/null` \
+ && tryldflag LIBCC "$try_libcc"
+printf "using compiler runtime libraries: %s\n" "$LIBCC"
+
+# Figure out arch variants for archs with variants
+SUBARCH=
+t="$CFLAGS_C99FSE $CPPFLAGS $CFLAGS"
+
+if test "$ARCH" = "x86_64" ; then
+trycppif __ILP32__ "$t" && ARCH=x32