remove vis.h protected-visibility hack

since commit dc2f368e56 this has been
disabled by default, but was left available in case users unhappy with
the resulting size or performance regressions wanted to try to make it
work. now that we make widespread use of hidden visibility for
internal interfaces, this no longer makes sense. if any costly calls
remain they can be fixed with hidden aliases.

configure

@@ -31,7 +31,6 @@ Optional features:
   --enable-optimize=...   optimize listed components for speed over size [auto]
   --enable-debug          build with debugging information [disabled]
   --enable-warnings       build with recommended warnings flags [disabled]
-  --enable-visibility     use global visibility options to optimize PIC [no]
   --enable-wrapper=...    build given musl toolchain wrapper [auto]
   --disable-shared        inhibit building shared library [enabled]
   --disable-static        inhibit building static library [enabled]
@@ -135,7 +134,6 @@ target=
 optimize=auto
 debug=no
 warnings=no
-visibility=no
 shared=auto
 static=yes
 wrapper=auto
@@ -163,9 +161,6 @@ case "$arg" in
 --disable-debug|--enable-debug=no) debug=no ;;
 --enable-warnings|--enable-warnings=yes) warnings=yes ;;
 --disable-warnings|--enable-warnings=no) warnings=no ;;
---enable-visibility=auto) visibility=auto ;;
---enable-visibility|--enable-visibility=yes) visibility=yes ;;
---disable-visibility|--enable-visibility=no) visibility=no ;;
 --enable-wrapper|--enable-wrapper=yes) wrapper=detect ;;
 --enable-wrapper=all) wrapper=yes ; gcc_wrapper=yes ; clang_wrapper=yes ;;
 --enable-wrapper=gcc) wrapper=yes ; gcc_wrapper=yes ;;
@@ -525,39 +520,6 @@ tryflag CFLAGS_AUTO -Wno-unknown-pragmas
 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
-
 # Determine if the compiler produces position-independent code (PIC)
 # by default. If so, we don't need to compile separate object files
 # for libc.a and libc.so.

src/internal/vis.h

@@ -1,27 +0,0 @@
-/* This file is only used if enabled in the build system, in which case it is
- * included automatically via command line options. It is not included
- * explicitly by any source files or other headers. Its purpose is to
- * override default visibilities to reduce the size and performance costs
- * of position-independent code. */
-
-#if !defined(CRT) && !defined(__ASSEMBLER__)
-
-/* Conceptually, all symbols should be protected, but some toolchains
- * fail to support copy relocations for protected data, so exclude all
- * exported data symbols. */
-
-__attribute__((__visibility__("default")))
-extern struct _IO_FILE *const stdin, *const stdout, *const stderr;
-
-__attribute__((__visibility__("default")))
-extern int optind, opterr, optopt, optreset, __optreset, getdate_err, h_errno, daylight, __daylight, signgam, __signgam;
-
-__attribute__((__visibility__("default")))
-extern long timezone, __timezone;
-
-__attribute__((__visibility__("default")))
-extern char *optarg, **environ, **__environ, *tzname[2], *__tzname[2], *__progname, *__progname_full;
-
-#pragma GCC visibility push(protected)
-
-#endif