Add --enable-build-with-cxx configure switch

This new option, disabled by default for now, allows specifying
whether to build GDB, GDBserver, and friends with a C++ (98/03)
compiler.

The name of the switch should be familiar to those who followed GCC's
own C++ conversion process.

. Adding -fpermissive to COMPILER in C++ mode (see the new
build-with-cxx.m4 file) makes errors like these be warnings instead:

  gdb/infrun.c:6597:1: error:   initializing argument 1 of ‘void sig_print_info(gdb_signal)’ [-fpermissive]
   sig_print_info (enum gdb_signal oursig)
   ^
  gdb/infrun.c: In function ‘void do_restore_infcall_suspend_state_cleanup(void*)’:
  gdb/infrun.c:7164:39: error: invalid conversion from ‘void*’ to ‘infcall_suspend_state*’ [-fpermissive]
     restore_infcall_suspend_state (state);
				 ^

so that the compiler carries on compiling the file.  -Werror still
catches the warnings, so nothing is lost, only our lifes are made
easier by concentrating on getting other more important things out of
the way first.

There's no way to quiet those warnings.  Until they're all fixed, when
building in C++ mode, -Werror is disabled by default.

. Adding -Wno-narrowing suppresses thousands of instances of this warning:

  gdb/arm-linux-tdep.c:439:1: error: narrowing conversion of ‘-1’ from ‘int’ to ‘ULONGEST {aka long unsigned int}’ inside { } is ill-formed in C++11 [-Werror=narrowing]
  gdb/arm-linux-tdep.c:439:1: error: narrowing conversion of ‘-1l’ from ‘LONGEST {aka long int}’ to ‘ULONGEST {aka long unsigned int}’ inside { } is ill-formed in C++11 [-Werror=narrowing]
  gdb/arm-linux-tdep.c:450:1: error: narrowing conversion of ‘-1’ from ‘int’ to ‘ULONGEST {aka long unsigned int}’ inside { } is ill-formed in C++11 [-Werror=narrowing]

We can defer handling those until we target C++11.


. Adding -Wno-sign-compare suppresses thousands of instances of this warning:

  gdb/linux-record.c:1763:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
	 if (tmpulongest == tdep->fcntl_F_GETLK64)
				  ^


. Adding -Wno-write-strings suppresses thousands of instances of this warning:

  gdb/mi/mi-cmd-var.c: In function ‘void mi_cmd_var_show_attributes(char*, char**, int)’:
  gdb/mi/mi-cmd-var.c:514:12: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
       attstr = "editable";
	      ^
  gdb/mi/mi-cmd-var.c:516:12: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings]
       attstr = "noneditable";
	      ^

For now, it's best to hide these warnings from view until we're
'-fpermissive'-clean, and can thus start building with -Werror.
The C compiler has always managed to build working GDBs with these
issues in the code, so a C++ compiler should too.

gdb/ChangeLog:
2015-02-27  Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMPILER): New, get it from autoconf.
	(COMPILE.pre, CC_LD): Use COMPILER.
	(CXX): Get from autoconf instead.
	(CXX_FOR_TARGET): Default to g++ instead of gcc.
	* acinclude.m4: Include build-with-cxx.m4.
	* build-with-cxx.m4: New file.
	* configure.ac: Call AC_PROG_CXX and GDB_AC_BUILD_WITH_CXX.
	Disable -Werror by default if building in C++ mode.
	(build_warnings): Add -Wno-sign-compare, -Wno-write-strings and
	-Wno-narrowing in C++ mode.  Only enable -Wpointer-sign in C mode.
	Run supported-warning-flags tests with the C++ compiler.
	Save/restore CXXFLAGS too.
	* configure: Regenerate.

gdb/gdbserver/ChangeLog:
2015-02-27  Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMPILER): New, get it from autoconf.
	(CXX): Get from autoconf instead.
	(COMPILE.pre): Use COMPILER.
	(CC-LD): Rename to ...
	(CC_LD): ... this.  Use COMPILER.
	(gdbserver$(EXEEXT), gdbreplay$(EXEEXT), $(IPA_LIB)): Adjust.
	(CXX_FOR_TARGET): Default to g++ instead of gcc.
	* acinclude.m4: Include build-with-cxx.m4.
	* configure.ac: Call AC_PROG_CXX and GDB_AC_BUILD_WITH_CXX.
	Disable -Werror by default if building in C++ mode.
	(build_warnings): Add -Wno-sign-compare, -Wno-write-strings and
	-Wno-narrowing in C++ mode. Run supported-warning-flags tests with
	the C++ compiler.  Save/restore CXXFLAGS too.
	* configure: Regenerate.

11 files changed, 908 insertions, 31 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index dfaad27..d897031 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,21 @@
 2015-02-27  Pedro Alves  <palves@redhat.com>
 
+	* Makefile.in (COMPILER): New, get it from autoconf.
+	(COMPILE.pre, CC_LD): Use COMPILER.
+	(CXX): Get from autoconf instead.
+	(CXX_FOR_TARGET): Default to g++ instead of gcc.
+	* acinclude.m4: Include build-with-cxx.m4.
+	* build-with-cxx.m4: New file.
+	* configure.ac: Call AC_PROG_CXX and GDB_AC_BUILD_WITH_CXX.
+	Disable -Werror by default if building in C++ mode.
+	(build_warnings): Add -Wno-sign-compare, -Wno-write-strings and
+	-Wno-narrowing in C++ mode.  Only enable -Wpointer-sign in C mode.
+	Run supported-warning-flags tests with the C++ compiler.
+	Save/restore CXXFLAGS too.
+	* configure: Regenerate.
+
+2015-02-27  Pedro Alves  <palves@redhat.com>
+
 	* libiberty.m4: New file.
 	* acinclude.m4: Include libiberty.m4.
 	* configure.ac: Call libiberty_INIT.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index e9f22d6..e837c6f 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -79,12 +79,16 @@ MSGMERGE = msgmerge
 PACKAGE = @PACKAGE@
 CATALOGS = @CATALOGS@
 
+# The name of the compiler to use.
+COMPILER = @COMPILER@
+
 # If you are compiling with GCC, make sure that either 1) You have the
 # fixed include files where GCC can reach them, or 2) You use the
 # -traditional flag.  Otherwise the ioctl calls in inflow.c
 # will be incorrectly compiled.  The "fixincludes" script in the gcc
 # distribution will fix your include files up.
 CC=@CC@
+CXX=@CXX@
 
 # Dependency tracking information.
 DEPMODE = @CCDEPMODE@
@@ -93,7 +97,7 @@ depcomp = $(SHELL) $(srcdir)/../depcomp
 
 # Note that these are overridden by GNU make-specific code below if
 # GNU make is used.  The overrides implement dependency tracking.
-COMPILE.pre = $(CC)
+COMPILE.pre = $(COMPILER)
 COMPILE.post = -c -o $@
 COMPILE = $(COMPILE.pre) $(INTERNAL_CFLAGS) $(COMPILE.post)
 POSTCOMPILE = @true
@@ -123,7 +127,7 @@ MAKEHTMLFLAGS =
 # Set this up with gcc if you have gnu ld and the loader will print out
 # line numbers for undefined references.
 #CC_LD=gcc -static
-CC_LD=$(CC)
+CC_LD=$(COMPILER)
 
 # Where is our "include" directory?  Typically $(srcdir)/../include.
 # This is essentially the header file directory for the library
@@ -762,19 +766,18 @@ CC_FOR_TARGET = ` \
     fi; \
   fi`
 
-CXX = gcc
 CXX_FOR_TARGET = ` \
-  if [ -f $${rootme}/../gcc/xgcc ] ; then \
+  if [ -f $${rootme}/../gcc/xg++ ] ; then \
     if [ -f $${rootme}/../$(target_subdir)newlib/Makefile ] ; then \
-      echo $${rootme}/../gcc/xgcc -B$${rootme}/../gcc/ -idirafter $${rootme}/$(target_subdir)newlib/targ-include -idirafter $${rootsrc}/../$(target_subdir)newlib/libc/include -nostdinc -B$${rootme}/../$(target_subdir)newlib/; \
+      echo $${rootme}/../gcc/xg++ -B$${rootme}/../gcc/ -idirafter $${rootme}/$(target_subdir)newlib/targ-include -idirafter $${rootsrc}/../$(target_subdir)newlib/libc/include -nostdinc -B$${rootme}/../$(target_subdir)newlib/; \
     else \
-      echo $${rootme}/../gcc/xgcc -B$${rootme}/../gcc/; \
+      echo $${rootme}/../gcc/xg++ -B$${rootme}/../gcc/; \
     fi; \
   else \
     if [ "$(host_canonical)" = "$(target_canonical)" ] ; then \
       echo $(CXX); \
     else \
-      t='$(program_transform_name)'; echo gcc | sed -e '' $$t; \
+      t='$(program_transform_name)'; echo g++ | sed -e '' $$t; \
     fi; \
   fi`
 
diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
index 0ad90e7..da22fc2 100644
--- a/gdb/acinclude.m4
+++ b/gdb/acinclude.m4
@@ -60,6 +60,9 @@ m4_include([common/common.m4])
 dnl For libiberty_INIT.
 m4_include(libiberty.m4)
 
+dnl For --enable-build-with-cxx and COMPILER.
+m4_include(build-with-cxx.m4)
+
 ## ----------------------------------------- ##
 ## ANSIfy the C compiler whenever possible.  ##
 ## From Franc,ois Pinard                     ##
diff --git a/gdb/build-with-cxx.m4 b/gdb/build-with-cxx.m4
new file mode 100644
index 0000000..8802f4d
--- /dev/null
+++ b/gdb/build-with-cxx.m4
@@ -0,0 +1,41 @@
+dnl Copyright (C) 2014-2015 Free Software Foundation, Inc.
+dnl
+dnl This file is part of GDB.
+dnl
+dnl This program is free software; you can redistribute it and/or modify
+dnl it under the terms of the GNU General Public License as published by
+dnl the Free Software Foundation; either version 3 of the License, or
+dnl (at your option) any later version.
+dnl
+dnl This program is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl GNU General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU General Public License
+dnl along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+dnl GDB_AC_BUILD_WITH_CXX()
+dnl Provide an --enable-build-with-cxx/--disable-build-with-cxx set of options
+dnl allowing a user to build with a C++ compiler.
+
+AC_DEFUN([GDB_AC_BUILD_WITH_CXX],
+[
+  AC_ARG_ENABLE(build-with-cxx,
+  AS_HELP_STRING([--enable-build-with-cxx], [build with C++ compiler instead of C compiler]),
+    [case $enableval in
+      yes | no)
+	  ;;
+      *)
+	  AC_MSG_ERROR([bad value $enableval for --enable-build-with-cxx]) ;;
+    esac],
+    [enable_build_with_cxx=no])
+
+  if test "$enable_build_with_cxx" = "yes"; then
+    # We're using -fpermissive as shortcut for now.
+    COMPILER='$(CXX) -fpermissive'
+   else
+    COMPILER='$(CC)'
+  fi
+  AC_SUBST(COMPILER)
+])
diff --git a/gdb/configure b/gdb/configure
index b1a7665..3297d37 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -724,6 +724,7 @@ MAKE
 CCDEPMODE
 DEPDIR
 am__leading_dot
+COMPILER
 INSTALL_STRIP_PROGRAM
 STRIP
 install_sh
@@ -742,6 +743,9 @@ build
 EGREP
 GREP
 CPP
+ac_ct_CXX
+CXXFLAGS
+CXX
 OBJEXT
 EXEEXT
 ac_ct_CC
@@ -796,6 +800,7 @@ enable_option_checking
 enable_maintainer_mode
 enable_plugins
 enable_largefile
+enable_build_with_cxx
 with_separate_debug_dir
 with_gdb_datadir
 with_relocated_sources
@@ -849,6 +854,9 @@ CFLAGS
 LDFLAGS
 LIBS
 CPPFLAGS
+CXX
+CXXFLAGS
+CCC
 CPP
 MAKEINFO
 MAKEINFOFLAGS
@@ -1484,6 +1492,7 @@ Optional Features:
 			  (and sometimes confusing) to the casual installer
   --enable-plugins        Enable support for plugins
   --disable-largefile     omit support for large files
+  --enable-build-with-cxx build with C++ compiler instead of C compiler
   --enable-targets=TARGETS
                           alternative target configurations
   --enable-64-bit-bfd     64-bit support (on hosts with narrower word sizes)
@@ -1567,6 +1576,8 @@ Some influential environment variables:
   LIBS        libraries to pass to the linker, e.g. -l<library>
   CPPFLAGS    C/C++/Objective C preprocessor flags, e.g. -I<include dir> if
               you have headers in a nonstandard directory <include dir>
+  CXX         C++ compiler command
+  CXXFLAGS    C++ compiler flags
   CPP         C preprocessor
   MAKEINFO    Parent configure detects if it is of sufficient version.
   MAKEINFOFLAGS
@@ -1696,6 +1707,44 @@ fi
 
 } # ac_fn_c_try_compile
 
+# ac_fn_cxx_try_compile LINENO
+# ----------------------------
+# Try to compile conftest.$ac_ext, and return whether this succeeded.
+ac_fn_cxx_try_compile ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  rm -f conftest.$ac_objext
+  if { { ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_compile") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    grep -v '^ *+' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    mv -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && {
+	 test -z "$ac_cxx_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then :
+  ac_retval=0
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_retval=1
+fi
+  eval $as_lineno_stack; test "x$as_lineno_stack" = x && { as_lineno=; unset as_lineno;}
+  return $ac_retval
+
+} # ac_fn_cxx_try_compile
+
 # ac_fn_c_try_cpp LINENO
 # ----------------------
 # Try to preprocess conftest.$ac_ext, and return whether this succeeded.
@@ -3487,6 +3536,264 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+if test -z "$CXX"; then
+  if test -n "$CCC"; then
+    CXX=$CCC
+  else
+    if test -n "$ac_tool_prefix"; then
+  for ac_prog in g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC
+  do
+    # Extract the first word of "$ac_tool_prefix$ac_prog", so it can be a program name with args.
+set dummy $ac_tool_prefix$ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if test "${ac_cv_prog_CXX+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$CXX"; then
+  ac_cv_prog_CXX="$CXX" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_CXX="$ac_tool_prefix$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+CXX=$ac_cv_prog_CXX
+if test -n "$CXX"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $CXX" >&5
+$as_echo "$CXX" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+    test -n "$CXX" && break
+  done
+fi
+if test -z "$CXX"; then
+  ac_ct_CXX=$CXX
+  for ac_prog in g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if test "${ac_cv_prog_ac_ct_CXX+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_CXX"; then
+  ac_cv_prog_ac_ct_CXX="$ac_ct_CXX" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_ac_ct_CXX="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_CXX=$ac_cv_prog_ac_ct_CXX
+if test -n "$ac_ct_CXX"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_CXX" >&5
+$as_echo "$ac_ct_CXX" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$ac_ct_CXX" && break
+done
+
+  if test "x$ac_ct_CXX" = x; then
+    CXX="g++"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    CXX=$ac_ct_CXX
+  fi
+fi
+
+  fi
+fi
+# Provide some information about the compiler.
+$as_echo "$as_me:${as_lineno-$LINENO}: checking for C++ compiler version" >&5
+set X $ac_compile
+ac_compiler=$2
+for ac_option in --version -v -V -qversion; do
+  { { ac_try="$ac_compiler $ac_option >&5"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_compiler $ac_option >&5") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    sed '10a\
+... rest of stderr output deleted ...
+         10q' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    rm -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+done
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether we are using the GNU C++ compiler" >&5
+$as_echo_n "checking whether we are using the GNU C++ compiler... " >&6; }
+if test "${ac_cv_cxx_compiler_gnu+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+#ifndef __GNUC__
+       choke me
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_compiler_gnu=yes
+else
+  ac_compiler_gnu=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_cv_cxx_compiler_gnu=$ac_compiler_gnu
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_cxx_compiler_gnu" >&5
+$as_echo "$ac_cv_cxx_compiler_gnu" >&6; }
+if test $ac_compiler_gnu = yes; then
+  GXX=yes
+else
+  GXX=
+fi
+ac_test_CXXFLAGS=${CXXFLAGS+set}
+ac_save_CXXFLAGS=$CXXFLAGS
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX accepts -g" >&5
+$as_echo_n "checking whether $CXX accepts -g... " >&6; }
+if test "${ac_cv_prog_cxx_g+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_cxx_werror_flag=$ac_cxx_werror_flag
+   ac_cxx_werror_flag=yes
+   ac_cv_prog_cxx_g=no
+   CXXFLAGS="-g"
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_prog_cxx_g=yes
+else
+  CXXFLAGS=""
+      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+
+else
+  ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+	 CXXFLAGS="-g"
+	 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_prog_cxx_g=yes
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+   ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cxx_g" >&5
+$as_echo "$ac_cv_prog_cxx_g" >&6; }
+if test "$ac_test_CXXFLAGS" = set; then
+  CXXFLAGS=$ac_save_CXXFLAGS
+elif test $ac_cv_prog_cxx_g = yes; then
+  if test "$GXX" = yes; then
+    CXXFLAGS="-g -O2"
+  else
+    CXXFLAGS="-g"
+  fi
+else
+  if test "$GXX" = yes; then
+    CXXFLAGS="-O2"
+  else
+    CXXFLAGS=
+  fi
+fi
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+
 
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
@@ -4634,6 +4941,30 @@ ac_script='s/[\\$]/&&/g;s/;s,x,x,$//'
 program_transform_name=`$as_echo "$program_transform_name" | sed "$ac_script"`
 
 
+# See if we are building with C++, and substitute COMPILER.
+
+  # Check whether --enable-build-with-cxx was given.
+if test "${enable_build_with_cxx+set}" = set; then :
+  enableval=$enable_build_with_cxx; case $enableval in
+      yes | no)
+	  ;;
+      *)
+	  as_fn_error "bad value $enableval for --enable-build-with-cxx" "$LINENO" 5 ;;
+    esac
+else
+  enable_build_with_cxx=no
+fi
+
+
+  if test "$enable_build_with_cxx" = "yes"; then
+    # We're using -fpermissive as shortcut for now.
+    COMPILER='$(CXX) -fpermissive'
+   else
+    COMPILER='$(CC)'
+  fi
+
+
+
 # Dependency checking.
 rm -rf .tst 2>/dev/null
 mkdir .tst 2>/dev/null
@@ -13038,8 +13369,11 @@ if test "${enable_werror+set}" = set; then :
 fi
 
 
-# Enable -Werror by default when using gcc.  Turn it off for releases.
-if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" && $development; then
+# Enable -Werror by default when using gcc in C mode.  Leave it off
+# for C++ until we're warning clean.  Turn it off for releases.
+if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" \
+   && test x"$enable_build_with_cxx" != x"yes" \
+   && $development; then
     ERROR_ON_WARNING=yes
 fi
 
@@ -13048,13 +13382,21 @@ if test "${ERROR_ON_WARNING}" = yes ; then
     WERROR_CFLAGS="-Werror"
 fi
 
+# These options work in either C or C++ modes.
 build_warnings="-Wall -Wdeclaration-after-statement -Wpointer-arith \
--Wpointer-sign \
 -Wno-unused -Wunused-value -Wunused-function \
 -Wno-switch -Wno-char-subscripts -Wmissing-prototypes \
 -Wdeclaration-after-statement -Wempty-body -Wmissing-parameter-type \
 -Wold-style-declaration -Wold-style-definition"
 
+# Now add in C and C++ specific options, depending on mode.
+if test "$enable_build_with_cxx" = "yes"; then
+   build_warnings="$build_warnings -Wno-sign-compare -Wno-write-strings \
+-Wno-narrowing"
+else
+   build_warnings="$build_warnings -Wpointer-sign"
+fi
+
 # Enable -Wno-format by default when using gcc on mingw since many
 # GCC versions complain about %I64.
 case "${host}" in
@@ -13092,6 +13434,18 @@ if test x"$silent" != x"yes" && test x"$build_warnings" != x""; then
   echo "Setting GDB specific compiler warning flags = $build_warnings" 6>&1
 fi
 fi
+
+# The set of warnings supported by a C++ compiler is not the same as
+# of the C compiler.
+if test "$enable_build_with_cxx" = "yes"; then
+    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+fi
+
 WARN_CFLAGS=""
 if test "x${build_warnings}" != x -a "x$GCC" = xyes
 then
@@ -13102,10 +13456,14 @@ $as_echo_n "checking compiler warning flags... " >&6; }
     for w in ${build_warnings}; do
 	case $w in
 	-Werr*) WERROR_CFLAGS=-Werror ;;
-	*) # Check that GCC accepts it
+	*)
+	    # Check whether GCC accepts it.
 	    saved_CFLAGS="$CFLAGS"
 	    CFLAGS="$CFLAGS $w"
-	    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+	    saved_CXXFLAGS="$CXXFLAGS"
+	    CXXFLAGS="$CXXFLAGS $w"
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -13116,11 +13474,12 @@ main ()
   return 0;
 }
 _ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
+if ac_fn_cxx_try_compile "$LINENO"; then :
   WARN_CFLAGS="${WARN_CFLAGS} $w"
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 	    CFLAGS="$saved_CFLAGS"
+	    CXXFLAGS="$saved_CXXFLAGS"
 	esac
     done
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${WARN_CFLAGS} ${WERROR_CFLAGS}" >&5
@@ -13129,6 +13488,15 @@ fi
 
 
 
+if test "$enable_build_with_cxx" = "yes"; then
+   ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+fi
+
 # In the Cygwin environment, we need some additional flags.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for cygwin" >&5
 $as_echo_n "checking for cygwin... " >&6; }
diff --git a/gdb/configure.ac b/gdb/configure.ac
index e72dfba..0898d0e 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -27,6 +27,8 @@ AM_MAINTAINER_MODE
 . $srcdir/../bfd/development.sh
 
 AC_PROG_CC
+AC_PROG_CXX
+
 AC_USE_SYSTEM_EXTENSIONS
 ACX_LARGEFILE
 AM_PROG_CC_STDC
@@ -36,6 +38,9 @@ AC_CONFIG_AUX_DIR(..)
 AC_CANONICAL_SYSTEM
 AC_ARG_PROGRAM
 
+# See if we are building with C++, and substitute COMPILER.
+GDB_AC_BUILD_WITH_CXX
+
 # Dependency checking.
 ZW_CREATE_DEPDIR
 ZW_PROG_COMPILER_DEPENDENCIES([CC])
@@ -1959,8 +1964,11 @@ AC_ARG_ENABLE(werror,
      *) AC_MSG_ERROR(bad value ${enableval} for --enable-werror) ;;
    esac])
 
-# Enable -Werror by default when using gcc.  Turn it off for releases.
-if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" && $development; then
+# Enable -Werror by default when using gcc in C mode.  Leave it off
+# for C++ until we're warning clean.  Turn it off for releases.
+if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" \
+   && test x"$enable_build_with_cxx" != x"yes" \
+   && $development; then
     ERROR_ON_WARNING=yes
 fi
 
@@ -1969,13 +1977,21 @@ if test "${ERROR_ON_WARNING}" = yes ; then
     WERROR_CFLAGS="-Werror"
 fi
 
+# These options work in either C or C++ modes.
 build_warnings="-Wall -Wdeclaration-after-statement -Wpointer-arith \
--Wpointer-sign \
 -Wno-unused -Wunused-value -Wunused-function \
 -Wno-switch -Wno-char-subscripts -Wmissing-prototypes \
 -Wdeclaration-after-statement -Wempty-body -Wmissing-parameter-type \
 -Wold-style-declaration -Wold-style-definition"
 
+# Now add in C and C++ specific options, depending on mode.
+if test "$enable_build_with_cxx" = "yes"; then
+   build_warnings="$build_warnings -Wno-sign-compare -Wno-write-strings \
+-Wno-narrowing"
+else
+   build_warnings="$build_warnings -Wpointer-sign"
+fi
+
 # Enable -Wno-format by default when using gcc on mingw since many
 # GCC versions complain about %I64.
 case "${host}" in
@@ -2011,6 +2027,13 @@ esac
 if test x"$silent" != x"yes" && test x"$build_warnings" != x""; then
   echo "Setting GDB specific compiler warning flags = $build_warnings" 6>&1
 fi])dnl
+
+# The set of warnings supported by a C++ compiler is not the same as
+# of the C compiler.
+if test "$enable_build_with_cxx" = "yes"; then
+    AC_LANG_PUSH([C++])
+fi
+
 WARN_CFLAGS=""
 if test "x${build_warnings}" != x -a "x$GCC" = xyes
 then
@@ -2020,11 +2043,15 @@ then
     for w in ${build_warnings}; do
 	case $w in
 	-Werr*) WERROR_CFLAGS=-Werror ;;
-	*) # Check that GCC accepts it
+	*)
+	    # Check whether GCC accepts it.
 	    saved_CFLAGS="$CFLAGS"
 	    CFLAGS="$CFLAGS $w"
+	    saved_CXXFLAGS="$CXXFLAGS"
+	    CXXFLAGS="$CXXFLAGS $w"
 	    AC_TRY_COMPILE([],[],WARN_CFLAGS="${WARN_CFLAGS} $w",)
 	    CFLAGS="$saved_CFLAGS"
+	    CXXFLAGS="$saved_CXXFLAGS"
 	esac
     done
     AC_MSG_RESULT(${WARN_CFLAGS} ${WERROR_CFLAGS})
@@ -2032,6 +2059,10 @@ fi
 AC_SUBST(WARN_CFLAGS)
 AC_SUBST(WERROR_CFLAGS)
 
+if test "$enable_build_with_cxx" = "yes"; then
+   AC_LANG_POP([C++])
+fi
+
 # In the Cygwin environment, we need some additional flags.
 AC_CACHE_CHECK([for cygwin], gdb_cv_os_cygwin,
 [AC_EGREP_CPP(^lose$, [
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 28b582f..111ed5b 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,5 +1,22 @@
 2015-02-27  Pedro Alves  <palves@redhat.com>
 
+	* Makefile.in (COMPILER): New, get it from autoconf.
+	(CXX): Get from autoconf instead.
+	(COMPILE.pre): Use COMPILER.
+	(CC-LD): Rename to ...
+	(CC_LD): ... this.  Use COMPILER.
+	(gdbserver$(EXEEXT), gdbreplay$(EXEEXT), $(IPA_LIB)): Adjust.
+	(CXX_FOR_TARGET): Default to g++ instead of gcc.
+	* acinclude.m4: Include build-with-cxx.m4.
+	* configure.ac: Call AC_PROG_CXX and GDB_AC_BUILD_WITH_CXX.
+	Disable -Werror by default if building in C++ mode.
+	(build_warnings): Add -Wno-sign-compare, -Wno-write-strings and
+	-Wno-narrowing in C++ mode. Run supported-warning-flags tests with
+	the C++ compiler.  Save/restore CXXFLAGS too.
+	* configure: Regenerate.
+
+2015-02-27  Pedro Alves  <palves@redhat.com>
+
 	* acinclude.m4: Include libiberty.m4.
 	* configure.ac: Call libiberty_INIT.
 	* config.in, configure: Regenerate.
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index e479c7c..cb35470 100644
--- a/gdb/gdbserver/Makefile.in
+++ b/gdb/gdbserver/Makefile.in
@@ -49,7 +49,11 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@
 INSTALL_DATA = @INSTALL_DATA@
 RANLIB = @RANLIB@
 
+# The name of the compiler to use.
+COMPILER = @COMPILER@
+
 CC = @CC@
+CXX = @CXX@
 AR = @AR@
 AR_FLAGS = rc
 
@@ -60,7 +64,7 @@ depcomp = $(SHELL) $(srcdir)/../depcomp
 
 # Note that these are overridden by GNU make-specific code below if
 # GNU make is used.  The overrides implement dependency tracking.
-COMPILE.pre = $(CC)
+COMPILE.pre = $(COMPILER)
 COMPILE.post = -c -o $@
 COMPILE = $(COMPILE.pre) $(INTERNAL_CFLAGS) $(COMPILE.post)
 POSTCOMPILE = @true
@@ -78,8 +82,8 @@ VPATH = @srcdir@
 
 # Set this up with gcc if you have gnu ld and the loader will print out
 # line numbers for undefinded refs.
-#CC-LD=gcc -static
-CC-LD=${CC}
+#CC_LD=gcc -static
+CC_LD=$(COMPILER)
 
 # Where is the "include" directory?  Traditionally ../include or ./include
 INCLUDE_DIR =  ${srcdir}/../../include
@@ -294,7 +298,7 @@ clean-info: force
 
 gdbserver$(EXEEXT): $(OBS) ${ADD_DEPS} ${CDEPS} $(LIBGNU) $(LIBIBERTY)
 	rm -f gdbserver$(EXEEXT)
-	${CC-LD} $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) -o gdbserver$(EXEEXT) $(OBS) \
+	$(CC_LD) $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) -o gdbserver$(EXEEXT) $(OBS) \
 	$(LIBGNU) $(LIBIBERTY) $(GDBSERVER_LIBS) $(XM_CLIBS)
 
 $(LIBGNU) $(LIBIBERTY) $(GNULIB_H): all-lib
@@ -304,7 +308,7 @@ all-lib: $(GNULIB_BUILDDIR)/Makefile $(LIBIBERTY_BUILDDIR)/Makefile
 
 gdbreplay$(EXEEXT): $(GDBREPLAY_OBS) $(LIBGNU) $(LIBIBERTY)
 	rm -f gdbreplay$(EXEEXT)
-	${CC-LD} $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) -o gdbreplay$(EXEEXT) $(GDBREPLAY_OBS) \
+	$(CC_LD) $(INTERNAL_CFLAGS) $(INTERNAL_LDFLAGS) -o gdbreplay$(EXEEXT) $(GDBREPLAY_OBS) \
 	  $(XM_CLIBS) $(LIBGNU) $(LIBIBERTY)
 
 IPA_OBJS=ax-ipa.o tracepoint-ipa.o format-ipa.o utils-ipa.o \
@@ -316,7 +320,7 @@ IPA_LIB=libinproctrace.so
 
 $(IPA_LIB): $(IPA_OBJS) ${ADD_DEPS} ${CDEPS}
 	rm -f $(IPA_LIB)
-	${CC-LD} -shared -fPIC -Wl,--no-undefined $(INTERNAL_CFLAGS) \
+	$(CC_LD) -shared -fPIC -Wl,--no-undefined $(INTERNAL_CFLAGS) \
 	$(INTERNAL_LDFLAGS) -o $(IPA_LIB) ${IPA_OBJS} -ldl -pthread
 
 # Put the proper machine-specific files first, so M-. on a machine
diff --git a/gdb/gdbserver/acinclude.m4 b/gdb/gdbserver/acinclude.m4
index e5f4b76..0b86c04 100644
--- a/gdb/gdbserver/acinclude.m4
+++ b/gdb/gdbserver/acinclude.m4
@@ -23,6 +23,9 @@ m4_include(../common/common.m4)
 dnl For libiberty_INIT.
 m4_include(../libiberty.m4)
 
+dnl For --enable-build-with-cxx and COMPILER.
+m4_include(../build-with-cxx.m4)
+
 dnl Check for existence of a type $1 in libthread_db.h
 dnl Based on BFD_HAVE_SYS_PROCFS_TYPE in bfd/bfd.m4.
 
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index 7c39130..a14def9 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -615,6 +615,7 @@ DEPDIR
 am__leading_dot
 host_noncanonical
 target_noncanonical
+COMPILER
 RANLIB
 AR
 INSTALL_DATA
@@ -635,6 +636,9 @@ build
 EGREP
 GREP
 CPP
+ac_ct_CXX
+CXXFLAGS
+CXX
 OBJEXT
 EXEEXT
 ac_ct_CC
@@ -688,6 +692,7 @@ ac_user_opts='
 enable_option_checking
 enable_maintainer_mode
 enable_largefile
+enable_build_with_cxx
 enable_libmcheck
 with_ust
 with_ust_include
@@ -706,6 +711,9 @@ CFLAGS
 LDFLAGS
 LIBS
 CPPFLAGS
+CXX
+CXXFLAGS
+CCC
 CPP'
 
 
@@ -1328,6 +1336,7 @@ Optional Features:
   --enable-maintainer-mode  enable make rules and dependencies not useful
 			  (and sometimes confusing) to the casual installer
   --disable-largefile     omit support for large files
+  --enable-build-with-cxx build with C++ compiler instead of C compiler
   --enable-libmcheck      Try linking with -lmcheck if available
   --enable-werror         treat compile warnings as errors
   --enable-inprocess-agent
@@ -1354,6 +1363,8 @@ Some influential environment variables:
   LIBS        libraries to pass to the linker, e.g. -l<library>
   CPPFLAGS    C/C++/Objective C preprocessor flags, e.g. -I<include dir> if
               you have headers in a nonstandard directory <include dir>
+  CXX         C++ compiler command
+  CXXFLAGS    C++ compiler flags
   CPP         C preprocessor
 
 Use these variables to override the choices made by `configure' or to help
@@ -1474,6 +1485,44 @@ fi
 
 } # ac_fn_c_try_compile
 
+# ac_fn_cxx_try_compile LINENO
+# ----------------------------
+# Try to compile conftest.$ac_ext, and return whether this succeeded.
+ac_fn_cxx_try_compile ()
+{
+  as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
+  rm -f conftest.$ac_objext
+  if { { ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_compile") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    grep -v '^ *+' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    mv -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; } && {
+	 test -z "$ac_cxx_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then :
+  ac_retval=0
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_retval=1
+fi
+  eval $as_lineno_stack; test "x$as_lineno_stack" = x && { as_lineno=; unset as_lineno;}
+  return $ac_retval
+
+} # ac_fn_cxx_try_compile
+
 # ac_fn_c_try_cpp LINENO
 # ----------------------
 # Try to preprocess conftest.$ac_ext, and return whether this succeeded.
@@ -3206,6 +3255,263 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+if test -z "$CXX"; then
+  if test -n "$CCC"; then
+    CXX=$CCC
+  else
+    if test -n "$ac_tool_prefix"; then
+  for ac_prog in g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC
+  do
+    # Extract the first word of "$ac_tool_prefix$ac_prog", so it can be a program name with args.
+set dummy $ac_tool_prefix$ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if test "${ac_cv_prog_CXX+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$CXX"; then
+  ac_cv_prog_CXX="$CXX" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_CXX="$ac_tool_prefix$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+CXX=$ac_cv_prog_CXX
+if test -n "$CXX"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $CXX" >&5
+$as_echo "$CXX" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+    test -n "$CXX" && break
+  done
+fi
+if test -z "$CXX"; then
+  ac_ct_CXX=$CXX
+  for ac_prog in g++ c++ gpp aCC CC cxx cc++ cl.exe FCC KCC RCC xlC_r xlC
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if test "${ac_cv_prog_ac_ct_CXX+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_CXX"; then
+  ac_cv_prog_ac_ct_CXX="$ac_ct_CXX" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_ac_ct_CXX="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_CXX=$ac_cv_prog_ac_ct_CXX
+if test -n "$ac_ct_CXX"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_CXX" >&5
+$as_echo "$ac_ct_CXX" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$ac_ct_CXX" && break
+done
+
+  if test "x$ac_ct_CXX" = x; then
+    CXX="g++"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    CXX=$ac_ct_CXX
+  fi
+fi
+
+  fi
+fi
+# Provide some information about the compiler.
+$as_echo "$as_me:${as_lineno-$LINENO}: checking for C++ compiler version" >&5
+set X $ac_compile
+ac_compiler=$2
+for ac_option in --version -v -V -qversion; do
+  { { ac_try="$ac_compiler $ac_option >&5"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:${as_lineno-$LINENO}: $ac_try_echo\""
+$as_echo "$ac_try_echo"; } >&5
+  (eval "$ac_compiler $ac_option >&5") 2>conftest.err
+  ac_status=$?
+  if test -s conftest.err; then
+    sed '10a\
+... rest of stderr output deleted ...
+         10q' conftest.err >conftest.er1
+    cat conftest.er1 >&5
+    rm -f conftest.er1 conftest.err
+  fi
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }
+done
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether we are using the GNU C++ compiler" >&5
+$as_echo_n "checking whether we are using the GNU C++ compiler... " >&6; }
+if test "${ac_cv_cxx_compiler_gnu+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+#ifndef __GNUC__
+       choke me
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_compiler_gnu=yes
+else
+  ac_compiler_gnu=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_cv_cxx_compiler_gnu=$ac_compiler_gnu
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_cxx_compiler_gnu" >&5
+$as_echo "$ac_cv_cxx_compiler_gnu" >&6; }
+if test $ac_compiler_gnu = yes; then
+  GXX=yes
+else
+  GXX=
+fi
+ac_test_CXXFLAGS=${CXXFLAGS+set}
+ac_save_CXXFLAGS=$CXXFLAGS
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX accepts -g" >&5
+$as_echo_n "checking whether $CXX accepts -g... " >&6; }
+if test "${ac_cv_prog_cxx_g+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_cxx_werror_flag=$ac_cxx_werror_flag
+   ac_cxx_werror_flag=yes
+   ac_cv_prog_cxx_g=no
+   CXXFLAGS="-g"
+   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_prog_cxx_g=yes
+else
+  CXXFLAGS=""
+      cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+
+else
+  ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+	 CXXFLAGS="-g"
+	 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_prog_cxx_g=yes
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+   ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cxx_g" >&5
+$as_echo "$ac_cv_prog_cxx_g" >&6; }
+if test "$ac_test_CXXFLAGS" = set; then
+  CXXFLAGS=$ac_save_CXXFLAGS
+elif test $ac_cv_prog_cxx_g = yes; then
+  if test "$GXX" = yes; then
+    CXXFLAGS="-g -O2"
+  else
+    CXXFLAGS="-g"
+  fi
+else
+  if test "$GXX" = yes; then
+    CXXFLAGS="-O2"
+  else
+    CXXFLAGS=
+  fi
+fi
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
 
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'
@@ -4403,6 +4709,30 @@ $as_echo "#define STDC_HEADERS 1" >>confdefs.h
 fi
 
 
+# See if we are building with C++, and substitute COMPILER.
+
+  # Check whether --enable-build-with-cxx was given.
+if test "${enable_build_with_cxx+set}" = set; then :
+  enableval=$enable_build_with_cxx; case $enableval in
+      yes | no)
+	  ;;
+      *)
+	  as_fn_error "bad value $enableval for --enable-build-with-cxx" "$LINENO" 5 ;;
+    esac
+else
+  enable_build_with_cxx=no
+fi
+
+
+  if test "$enable_build_with_cxx" = "yes"; then
+    # We're using -fpermissive as shortcut for now.
+    COMPILER='$(CXX) -fpermissive'
+   else
+    COMPILER='$(CC)'
+  fi
+
+
+
 # Set the 'development' global.
 . $srcdir/../../bfd/development.sh
 
@@ -5451,8 +5781,11 @@ if test "${enable_werror+set}" = set; then :
 fi
 
 
-# Enable -Werror by default when using gcc.  Turn it off for releases.
-if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" && $development; then
+# Enable -Werror by default when using gcc in C mode.  Leave it off
+# for C++ until we're warning clean.  Turn it off for releases.
+if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" \
+   && test x"$enable_build_with_cxx" != x"yes" \
+   && $development; then
     ERROR_ON_WARNING=yes
 fi
 
@@ -5464,6 +5797,23 @@ fi
 build_warnings="-Wall -Wdeclaration-after-statement -Wpointer-arith \
 -Wformat-nonliteral -Wno-char-subscripts -Wempty-body"
 
+# Now add in C and C++ specific options, depending on mode.
+if test "$enable_build_with_cxx" = "yes"; then
+   build_warnings="$build_warnings -Wno-sign-compare -Wno-write-strings \
+-Wno-narrowing"
+fi
+
+# The set of warnings supported by a C++ compiler is not the same as
+# of the C compiler.
+if test "$enable_build_with_cxx" = "yes"; then
+    ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+fi
+
 WARN_CFLAGS=""
 if test "x$GCC" = xyes
 then
@@ -5474,10 +5824,14 @@ $as_echo_n "checking compiler warning flags... " >&6; }
     for w in ${build_warnings}; do
 	case $w in
 	-Werr*) WERROR_CFLAGS=-Werror ;;
-	*) # Check that GCC accepts it
+	*)
+	    # Check whether GCC accepts it.
 	    saved_CFLAGS="$CFLAGS"
 	    CFLAGS="$CFLAGS $w"
-	    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+	    saved_CXXFLAGS="$CXXFLAGS"
+	    CXXFLAGS="$CXXFLAGS $w"
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -5488,11 +5842,12 @@ main ()
   return 0;
 }
 _ACEOF
-if ac_fn_c_try_compile "$LINENO"; then :
+if ac_fn_cxx_try_compile "$LINENO"; then :
   WARN_CFLAGS="${WARN_CFLAGS} $w"
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 	    CFLAGS="$saved_CFLAGS"
+	    CXXFLAGS="$saved_CXXFLAGS"
 	esac
     done
     { $as_echo "$as_me:${as_lineno-$LINENO}: result: ${WARN_CFLAGS} ${WERROR_CFLAGS}" >&5
@@ -5501,6 +5856,15 @@ fi
 
 
 
+if test "$enable_build_with_cxx" = "yes"; then
+   ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+fi
+
 old_LIBS="$LIBS"
 LIBS="$LIBS -ldl"
 for ac_func in dladdr
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index 60636f7..cefc69e 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -26,6 +26,7 @@ AC_CONFIG_HEADER(config.h:config.in)
 AM_MAINTAINER_MODE
 
 AC_PROG_CC
+AC_PROG_CXX
 AC_GNU_SOURCE
 AC_SYS_LARGEFILE
 
@@ -39,6 +40,9 @@ AC_ARG_PROGRAM
 
 AC_HEADER_STDC
 
+# See if we are building with C++, and substitute COMPILER.
+GDB_AC_BUILD_WITH_CXX
+
 # Set the 'development' global.
 . $srcdir/../../bfd/development.sh
 
@@ -150,8 +154,11 @@ AC_ARG_ENABLE(werror,
      *) AC_MSG_ERROR(bad value ${enableval} for --enable-werror) ;;
    esac])
 
-# Enable -Werror by default when using gcc.  Turn it off for releases.
-if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" && $development; then
+# Enable -Werror by default when using gcc in C mode.  Leave it off
+# for C++ until we're warning clean.  Turn it off for releases.
+if test "${GCC}" = yes -a -z "${ERROR_ON_WARNING}" \
+   && test x"$enable_build_with_cxx" != x"yes" \
+   && $development; then
     ERROR_ON_WARNING=yes
 fi
 
@@ -163,6 +170,18 @@ fi
 build_warnings="-Wall -Wdeclaration-after-statement -Wpointer-arith \
 -Wformat-nonliteral -Wno-char-subscripts -Wempty-body"
 
+# Now add in C and C++ specific options, depending on mode.
+if test "$enable_build_with_cxx" = "yes"; then
+   build_warnings="$build_warnings -Wno-sign-compare -Wno-write-strings \
+-Wno-narrowing"
+fi
+
+# The set of warnings supported by a C++ compiler is not the same as
+# of the C compiler.
+if test "$enable_build_with_cxx" = "yes"; then
+    AC_LANG_PUSH([C++])
+fi
+
 WARN_CFLAGS=""
 if test "x$GCC" = xyes
 then
@@ -172,11 +191,15 @@ then
     for w in ${build_warnings}; do
 	case $w in
 	-Werr*) WERROR_CFLAGS=-Werror ;;
-	*) # Check that GCC accepts it
+	*)
+	    # Check whether GCC accepts it.
 	    saved_CFLAGS="$CFLAGS"
 	    CFLAGS="$CFLAGS $w"
+	    saved_CXXFLAGS="$CXXFLAGS"
+	    CXXFLAGS="$CXXFLAGS $w"
 	    AC_TRY_COMPILE([],[],WARN_CFLAGS="${WARN_CFLAGS} $w",)
 	    CFLAGS="$saved_CFLAGS"
+	    CXXFLAGS="$saved_CXXFLAGS"
 	esac
     done
     AC_MSG_RESULT(${WARN_CFLAGS} ${WERROR_CFLAGS})
@@ -184,6 +207,10 @@ fi
 AC_SUBST(WARN_CFLAGS)
 AC_SUBST(WERROR_CFLAGS)
 
+if test "$enable_build_with_cxx" = "yes"; then
+   AC_LANG_POP([C++])
+fi
+
 dnl dladdr is glibc-specific.  It is used by thread-db.c but only for
 dnl debugging messages.  It lives in -ldl which is handled below so we don't
 dnl use AC_CHECK_LIB (or AC_SEARCH_LIBS) here.  Instead we just temporarily