gdbserver/linux: probe for libiconv in configure

diff --git a/gdbserver/Makefile.in b/gdbserver/Makefile.in
index d12f8746611b..c7120895a26d 100644
--- a/gdbserver/Makefile.in
+++ b/gdbserver/Makefile.in
@@ -152,6 +152,8 @@  PTHREAD_LIBS = @PTHREAD_LIBS@
 
 WIN32APILIBS = @WIN32APILIBS@
 
+MAYBE_LIBICONV = @MAYBE_LIBICONV@
+
 # INTERNAL_CFLAGS is the aggregate of all other *CFLAGS macros.
 INTERNAL_CFLAGS_BASE = ${GLOBAL_CFLAGS} \
 	${PROFILE_CFLAGS} ${INCLUDE_CFLAGS} ${CPPFLAGS} $(PTHREAD_CFLAGS)
@@ -354,7 +356,7 @@  gdbserver$(EXEEXT): $(sort $(OBS)) ${CDEPS} $(LIBGNU) $(LIBIBERTY) \
 		$(CXXFLAGS) \
 		-o gdbserver$(EXEEXT) $(OBS) $(GDBSUPPORT) $(LIBGNU) \
 		$(LIBGNU_EXTRA_LIBS) $(LIBIBERTY) $(INTL) \
-		$(GDBSERVER_LIBS) $(XM_CLIBS) $(WIN32APILIBS)
+		$(GDBSERVER_LIBS) $(XM_CLIBS) $(WIN32APILIBS) $(MAYBE_LIBICONV)
 
 gdbreplay$(EXEEXT): $(sort $(GDBREPLAY_OBS)) $(LIBGNU) $(LIBIBERTY) \
 		$(INTL_DEPS) $(GDBSUPPORT)
diff --git a/gdbserver/acinclude.m4 b/gdbserver/acinclude.m4
index db69b7d243b1..5a00c6e9878b 100644
--- a/gdbserver/acinclude.m4
+++ b/gdbserver/acinclude.m4
@@ -18,6 +18,13 @@  dnl anything else in gdbserver.
 m4_include(../config/codeset.m4)
 m4_include(../gdbsupport/common.m4)
 
+dnl For AM_ICONV.  We need to explicitly include these other files before
+dnl iconv.m4 to avoid warnings.
+m4_include([../config/lib-ld.m4])
+m4_include([../config/lib-prefix.m4])
+m4_include([../config/lib-link.m4])
+m4_include([../config/iconv.m4])
+
 dnl For libiberty_INIT.
 m4_include(../gdbsupport/libiberty.m4)
 
diff --git a/gdbserver/aclocal.m4 b/gdbserver/aclocal.m4
index db9266266bed..fe94a5bffc05 100644
--- a/gdbserver/aclocal.m4
+++ b/gdbserver/aclocal.m4
@@ -204,12 +204,8 @@  m4_include([../config/ax_pthread.m4])
 m4_include([../config/depstand.m4])
 m4_include([../config/gettext-sister.m4])
 m4_include([../config/gettext.m4])
-m4_include([../config/iconv.m4])
 m4_include([../config/intlmacosx.m4])
 m4_include([../config/lead-dot.m4])
-m4_include([../config/lib-ld.m4])
-m4_include([../config/lib-link.m4])
-m4_include([../config/lib-prefix.m4])
 m4_include([../config/nls.m4])
 m4_include([../config/override.m4])
 m4_include([../config/po.m4])
diff --git a/gdbserver/config.in b/gdbserver/config.in
index ca4b9f4d6f20..47e1e722fe0a 100644
--- a/gdbserver/config.in
+++ b/gdbserver/config.in
@@ -402,6 +402,9 @@ 
 /* Define to 1 if you have the <ws2tcpip.h> header file. */
 #undef HAVE_WS2TCPIP_H
 
+/* Define as const if the declaration of iconv() needs const. */
+#undef ICONV_CONST
+
 /* Define to the address where bug reports for this package should be sent. */
 #undef PACKAGE_BUGREPORT
 
diff --git a/gdbserver/configure b/gdbserver/configure
index 0942ef173d45..ae8dfdc3a7e0 100755
--- a/gdbserver/configure
+++ b/gdbserver/configure
@@ -623,6 +623,7 @@  ac_header_list=
 gt_needs=
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+MAYBE_LIBICONV
 GNULIB_STDINT_H
 extra_libraries
 IPA_DEPFILES
@@ -14736,6 +14737,356 @@  if test x"$STDINT_H" != x; then
 fi
 
 
+# Check for libiconv if needed for the host.
+
+
+
+
+
+          am_save_CPPFLAGS="$CPPFLAGS"
+
+  for element in $INCICONV; do
+    haveit=
+    for x in $CPPFLAGS; do
+
+  acl_save_prefix="$prefix"
+  prefix="$acl_final_prefix"
+  acl_save_exec_prefix="$exec_prefix"
+  exec_prefix="$acl_final_exec_prefix"
+  eval x=\"$x\"
+  exec_prefix="$acl_save_exec_prefix"
+  prefix="$acl_save_prefix"
+
+      if test "X$x" = "X$element"; then
+        haveit=yes
+        break
+      fi
+    done
+    if test -z "$haveit"; then
+      CPPFLAGS="${CPPFLAGS}${CPPFLAGS:+ }$element"
+    fi
+  done
+
+
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for iconv" >&5
+$as_echo_n "checking for iconv... " >&6; }
+if ${am_cv_func_iconv+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+    am_cv_func_iconv="no, consider installing GNU libiconv"
+    am_cv_lib_iconv=no
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+#include <iconv.h>
+
+int
+main ()
+{
+iconv_t cd = iconv_open("","");
+           iconv(cd,NULL,NULL,NULL,NULL);
+           iconv_close(cd);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  am_cv_func_iconv=yes
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+    if test "$am_cv_func_iconv" != yes; then
+      am_save_LIBS="$LIBS"
+      LIBS="$LIBS $LIBICONV"
+      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+#include <iconv.h>
+
+int
+main ()
+{
+iconv_t cd = iconv_open("","");
+             iconv(cd,NULL,NULL,NULL,NULL);
+             iconv_close(cd);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  am_cv_lib_iconv=yes
+        am_cv_func_iconv=yes
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+      LIBS="$am_save_LIBS"
+    fi
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $am_cv_func_iconv" >&5
+$as_echo "$am_cv_func_iconv" >&6; }
+  if test "$am_cv_func_iconv" = yes; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for working iconv" >&5
+$as_echo_n "checking for working iconv... " >&6; }
+if ${am_cv_func_iconv_works+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+                  am_save_LIBS="$LIBS"
+      if test $am_cv_lib_iconv = yes; then
+        LIBS="$LIBS $LIBICONV"
+      fi
+      am_cv_func_iconv_works=no
+      for ac_iconv_const in '' 'const'; do
+        if test "$cross_compiling" = yes; then :
+  case "$host_os" in
+             aix* | hpux*) am_cv_func_iconv_works="guessing no" ;;
+             *)            am_cv_func_iconv_works="guessing yes" ;;
+           esac
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <iconv.h>
+#include <string.h>
+
+#ifndef ICONV_CONST
+# define ICONV_CONST $ac_iconv_const
+#endif
+
+int
+main ()
+{
+int result = 0;
+  /* Test against AIX 5.1...7.2 bug: Failures are not distinguishable from
+     successful returns.  This is even documented in
+     <https://www.ibm.com/support/knowledgecenter/ssw_aix_72/i_bostechref/iconv.html> */
+  {
+    iconv_t cd_utf8_to_88591 = iconv_open ("ISO8859-1", "UTF-8");
+    if (cd_utf8_to_88591 != (iconv_t)(-1))
+      {
+        static ICONV_CONST char input[] = "\342\202\254"; /* EURO SIGN */
+        char buf[10];
+        ICONV_CONST char *inptr = input;
+        size_t inbytesleft = strlen (input);
+        char *outptr = buf;
+        size_t outbytesleft = sizeof (buf);
+        size_t res = iconv (cd_utf8_to_88591,
+                            &inptr, &inbytesleft,
+                            &outptr, &outbytesleft);
+        if (res == 0)
+          result |= 1;
+        iconv_close (cd_utf8_to_88591);
+      }
+  }
+  /* Test against Solaris 10 bug: Failures are not distinguishable from
+     successful returns.  */
+  {
+    iconv_t cd_ascii_to_88591 = iconv_open ("ISO8859-1", "646");
+    if (cd_ascii_to_88591 != (iconv_t)(-1))
+      {
+        static ICONV_CONST char input[] = "\263";
+        char buf[10];
+        ICONV_CONST char *inptr = input;
+        size_t inbytesleft = strlen (input);
+        char *outptr = buf;
+        size_t outbytesleft = sizeof (buf);
+        size_t res = iconv (cd_ascii_to_88591,
+                            &inptr, &inbytesleft,
+                            &outptr, &outbytesleft);
+        if (res == 0)
+          result |= 2;
+        iconv_close (cd_ascii_to_88591);
+      }
+  }
+  /* Test against AIX 6.1..7.1 bug: Buffer overrun.  */
+  {
+    iconv_t cd_88591_to_utf8 = iconv_open ("UTF-8", "ISO-8859-1");
+    if (cd_88591_to_utf8 != (iconv_t)(-1))
+      {
+        static ICONV_CONST char input[] = "\304";
+        static char buf[2] = { (char)0xDE, (char)0xAD };
+        ICONV_CONST char *inptr = input;
+        size_t inbytesleft = 1;
+        char *outptr = buf;
+        size_t outbytesleft = 1;
+        size_t res = iconv (cd_88591_to_utf8,
+                            &inptr, &inbytesleft,
+                            &outptr, &outbytesleft);
+        if (res != (size_t)(-1) || outptr - buf > 1 || buf[1] != (char)0xAD)
+          result |= 4;
+        iconv_close (cd_88591_to_utf8);
+      }
+  }
+#if 0 /* This bug could be worked around by the caller.  */
+  /* Test against HP-UX 11.11 bug: Positive return value instead of 0.  */
+  {
+    iconv_t cd_88591_to_utf8 = iconv_open ("utf8", "iso88591");
+    if (cd_88591_to_utf8 != (iconv_t)(-1))
+      {
+        static ICONV_CONST char input[] = "\304rger mit b\366sen B\374bchen ohne Augenma\337";
+        char buf[50];
+        ICONV_CONST char *inptr = input;
+        size_t inbytesleft = strlen (input);
+        char *outptr = buf;
+        size_t outbytesleft = sizeof (buf);
+        size_t res = iconv (cd_88591_to_utf8,
+                            &inptr, &inbytesleft,
+                            &outptr, &outbytesleft);
+        if ((int)res > 0)
+          result |= 8;
+        iconv_close (cd_88591_to_utf8);
+      }
+  }
+#endif
+  /* Test against HP-UX 11.11 bug: No converter from EUC-JP to UTF-8 is
+     provided.  */
+  {
+    /* Try standardized names.  */
+    iconv_t cd1 = iconv_open ("UTF-8", "EUC-JP");
+    /* Try IRIX, OSF/1 names.  */
+    iconv_t cd2 = iconv_open ("UTF-8", "eucJP");
+    /* Try AIX names.  */
+    iconv_t cd3 = iconv_open ("UTF-8", "IBM-eucJP");
+    /* Try HP-UX names.  */
+    iconv_t cd4 = iconv_open ("utf8", "eucJP");
+    if (cd1 == (iconv_t)(-1) && cd2 == (iconv_t)(-1)
+        && cd3 == (iconv_t)(-1) && cd4 == (iconv_t)(-1))
+      result |= 16;
+    if (cd1 != (iconv_t)(-1))
+      iconv_close (cd1);
+    if (cd2 != (iconv_t)(-1))
+      iconv_close (cd2);
+    if (cd3 != (iconv_t)(-1))
+      iconv_close (cd3);
+    if (cd4 != (iconv_t)(-1))
+      iconv_close (cd4);
+  }
+  return result;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+  am_cv_func_iconv_works=yes
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+        test "$am_cv_func_iconv_works" = no || break
+      done
+      LIBS="$am_save_LIBS"
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $am_cv_func_iconv_works" >&5
+$as_echo "$am_cv_func_iconv_works" >&6; }
+    case "$am_cv_func_iconv_works" in
+      *no) am_func_iconv=no am_cv_lib_iconv=no ;;
+      *)   am_func_iconv=yes ;;
+    esac
+  else
+    am_func_iconv=no am_cv_lib_iconv=no
+  fi
+  if test "$am_func_iconv" = yes; then
+
+$as_echo "#define HAVE_ICONV 1" >>confdefs.h
+
+  fi
+  if test "$am_cv_lib_iconv" = yes; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking how to link with libiconv" >&5
+$as_echo_n "checking how to link with libiconv... " >&6; }
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $LIBICONV" >&5
+$as_echo "$LIBICONV" >&6; }
+  else
+            CPPFLAGS="$am_save_CPPFLAGS"
+    LIBICONV=
+    LTLIBICONV=
+  fi
+
+
+
+  if test "$am_cv_func_iconv" = yes; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether iconv is compatible with its POSIX signature" >&5
+$as_echo_n "checking whether iconv is compatible with its POSIX signature... " >&6; }
+if ${gl_cv_iconv_nonconst+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+#include <iconv.h>
+extern
+#ifdef __cplusplus
+"C"
+#endif
+size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  gl_cv_iconv_nonconst=yes
+else
+  gl_cv_iconv_nonconst=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gl_cv_iconv_nonconst" >&5
+$as_echo "$gl_cv_iconv_nonconst" >&6; }
+  else
+            gl_cv_iconv_nonconst=yes
+  fi
+  if test $gl_cv_iconv_nonconst = yes; then
+    iconv_arg1=""
+  else
+    iconv_arg1="const"
+  fi
+
+cat >>confdefs.h <<_ACEOF
+#define ICONV_CONST $iconv_arg1
+_ACEOF
+
+
+
+      if test "$am_func_iconv" = yes; then
+    if test -n "$LIBICONV"; then
+      am_cv_func_iconv_summary='yes, in libiconv'
+    else
+      am_cv_func_iconv_summary='yes, in libc'
+    fi
+  else
+    if test "$am_cv_func_iconv" = yes; then
+      am_cv_func_iconv_summary='not working, consider installing GNU libiconv'
+    else
+      am_cv_func_iconv_summary='no, consider installing GNU libiconv'
+    fi
+  fi
+
+MAYBE_LIBICONV=
+case "$host" in
+  *linux*)
+    if test "$am_cv_func_iconv" != yes; then
+      as_fn_error $? "could not find libiconv (required for host $host)" "$LINENO" 5
+    fi
+
+    MAYBE_LIBICONV="$LIBICONV"
+    ;;
+esac
+
+
+
 ac_config_files="$ac_config_files Makefile"
 
 
diff --git a/gdbserver/configure.ac b/gdbserver/configure.ac
index 280043dd7fc3..d9f61ac137f4 100644
--- a/gdbserver/configure.ac
+++ b/gdbserver/configure.ac
@@ -456,6 +456,21 @@  if test x"$STDINT_H" != x; then
 fi
 AC_SUBST(GNULIB_STDINT_H)
 
+# Check for libiconv if needed for the host.
+AM_ICONV
+MAYBE_LIBICONV=
+case "$host" in
+  *linux*)
+    if test "$am_cv_func_iconv" != yes; then
+      AC_MSG_ERROR([could not find libiconv (required for host $host)])
+    fi
+
+    MAYBE_LIBICONV="$LIBICONV"
+    ;;
+esac
+
+AC_SUBST(MAYBE_LIBICONV)
+
 AC_CONFIG_FILES([Makefile])
 
 AC_OUTPUT