gdb/: Require a C++ compiler

This removes all support for building gdb & gdbserver with a C
compiler from gdb & gdbserver's build machinery.

gdb/ChangeLog:
2016-09-05  Pedro Alves  <palves@redhat.com>

	* NEWS: Mention that a C++ compiler is now required.
	* Makefile.in (COMPILER, COMPILER_CFLAGS): Remove.
	(COMPILE.pre, CC_LD): Use CXX directly.
	(INTERNAL_CFLAGS_BASE): Use CXXFLAGS directly.
	* acinclude.m4: Don't include build-with-cxx.m4.
	* build-with-cxx.m4: Delete file.
	* configure.ac: Remove GDB_AC_BUILD_WITH_CXX call.
	* warning.m4: Assume $enable_build_with_cxx is yes.
	* configure: Regenerate.

gdb/gdbserver/ChangeLog:
2016-09-05  Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMPILER, COMPILER_CFLAGS): Remove.
	(COMPILE.pre, CC_LD): Use CXX directly.
	(INTERNAL_CFLAGS_BASE): Use CXXFLAGS directly.
	* acinclude.m4: Don't include build-with-cxx.m4.
	* configure.ac: Remove GDB_AC_BUILD_WITH_CXX call.
	* configure: Regenerate.

5 files changed, 18 insertions, 64 deletions

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 629254f..5e9e4cb 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,12 @@
+2016-09-05  Pedro Alves  <palves@redhat.com>
+
+	* Makefile.in (COMPILER, COMPILER_CFLAGS): Remove.
+	(COMPILE.pre, CC_LD): Use CXX directly.
+	(INTERNAL_CFLAGS_BASE): Use CXXFLAGS directly.
+	* acinclude.m4: Don't include build-with-cxx.m4.
+	* configure.ac: Remove GDB_AC_BUILD_WITH_CXX call.
+	* configure: Regenerate.
+
 2016-09-02  Akash Trehan  <akash.trehan123@gmail.com>
 
 	PR gdb/19495
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index f844ab8..309b496 100644
--- a/gdb/gdbserver/Makefile.in
+++ b/gdb/gdbserver/Makefile.in
@@ -49,11 +49,6 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@
 INSTALL_DATA = @INSTALL_DATA@
 RANLIB = @RANLIB@
 
-# The name of the compiler to use.
-COMPILER = @COMPILER@
-# Set to CFLAGS or CXXFLAGS, depending on compiler/language.
-COMPILER_CFLAGS = @COMPILER_CFLAGS@
-
 CC = @CC@
 CXX = @CXX@
 AR = @AR@
@@ -66,7 +61,7 @@ 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 = $(COMPILER)
+COMPILE.pre = $(CXX)
 COMPILE.post = -c -o $@
 COMPILE = $(COMPILE.pre) $(INTERNAL_CFLAGS) $(COMPILE.post)
 POSTCOMPILE = @true
@@ -84,8 +79,8 @@ 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=$(COMPILER)
+#CC_LD=g++ -static
+CC_LD=$(CXX)
 
 # Where is the "include" directory?  Traditionally ../include or ./include
 INCLUDE_DIR =  ${srcdir}/../../include
@@ -138,7 +133,7 @@ CXXFLAGS = @CXXFLAGS@
 CPPFLAGS = @CPPFLAGS@
 
 # INTERNAL_CFLAGS is the aggregate of all other *CFLAGS macros.
-INTERNAL_CFLAGS_BASE =  ${COMPILER_CFLAGS} ${GLOBAL_CFLAGS} \
+INTERNAL_CFLAGS_BASE =  ${CXXFLAGS} ${GLOBAL_CFLAGS} \
 	${PROFILE_CFLAGS} ${INCLUDE_CFLAGS} ${CPPFLAGS}
 INTERNAL_WARN_CFLAGS =  ${INTERNAL_CFLAGS_BASE} $(WARN_CFLAGS)
 INTERNAL_CFLAGS =  ${INTERNAL_WARN_CFLAGS} $(WERROR_CFLAGS) -DGDBSERVER
diff --git a/gdb/gdbserver/acinclude.m4 b/gdb/gdbserver/acinclude.m4
index a052c2b..8ec9188 100644
--- a/gdb/gdbserver/acinclude.m4
+++ b/gdb/gdbserver/acinclude.m4
@@ -26,9 +26,6 @@ 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 For GDB_AC_PTRACE.
 m4_include(../ptrace.m4)
 
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index 6b14b52..f112517 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -615,8 +615,6 @@ DEPDIR
 am__leading_dot
 host_noncanonical
 target_noncanonical
-COMPILER_CFLAGS
-COMPILER
 RANLIB
 AR
 INSTALL_DATA
@@ -693,7 +691,6 @@ ac_user_opts='
 enable_option_checking
 enable_maintainer_mode
 enable_largefile
-enable_build_with_cxx
 enable_libmcheck
 with_ust
 with_ust_include
@@ -1339,8 +1336,6 @@ 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
-  --disable-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-build-warnings enable build-time compiler warnings if gcc is used
@@ -4774,32 +4769,6 @@ $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=yes
-fi
-
-
-  if test "$enable_build_with_cxx" = "yes"; then
-    COMPILER='$(CXX)'
-    COMPILER_CFLAGS='$(CXXFLAGS)'
-   else
-    COMPILER='$(CC)'
-    COMPILER_CFLAGS='$(CFLAGS)'
-  fi
-
-
-
-
 # Set the 'development' global.
 . $srcdir/../../bfd/development.sh
 
@@ -6288,21 +6257,12 @@ if test "${ERROR_ON_WARNING}" = yes ; then
     WERROR_CFLAGS="-Werror"
 fi
 
-# These options work in either C or C++ modes.
+# The options we'll try to enable.
 build_warnings="-Wall -Wpointer-arith \
 -Wno-unused -Wunused-value -Wunused-function \
 -Wno-switch -Wno-char-subscripts \
--Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable"
-
-# 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 -Wmissing-prototypes \
--Wdeclaration-after-statement -Wmissing-parameter-type \
--Wold-style-declaration -Wold-style-definition"
-fi
+-Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable \
+-Wno-sign-compare -Wno-write-strings -Wno-narrowing"
 
 # Enable -Wno-format by default when using gcc on mingw since many
 # GCC versions complain about %I64.
@@ -6344,14 +6304,12 @@ fi
 
 # The set of warnings supported by a C++ compiler is not the same as
 # of the C compiler.
-if test "$enable_build_with_cxx" = "yes"; then
-    ac_ext=cpp
+ac_ext=cpp
 ac_cpp='$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
@@ -6403,14 +6361,12 @@ fi
 
 
 
-if test "$enable_build_with_cxx" = "yes"; then
-   ac_ext=c
+ac_ext=c
 ac_cpp='$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
 
 case " $WARN_CFLAGS " in
 *" -Wmissing-prototypes "*)
diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
index 01ec634..6d5907b 100644
--- a/gdb/gdbserver/configure.ac
+++ b/gdb/gdbserver/configure.ac
@@ -40,9 +40,6 @@ 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