debug: Prefer -Og if possible

Makefile.in

@@ -42,7 +42,7 @@ DIFF = @DIFF@
 LIBS = @LIBS@
 INCLUDES = @TCL_INCLUDES@ @SSL_INCLUDES@
 
-DEBCXXFLAGS = -DDEBUG -fno-inline -g3 -ggdb3 -O0 -Wshadow -Wpointer-arith @GCC3DEB@ @GCC4DEB@ @DEBCXXFLAGS@
+DEBCXXFLAGS = -DDEBUG -fno-inline -g3 -ggdb3 -Wshadow -Wpointer-arith @GCC3DEB@ @GCC4DEB@ @DEBCXXFLAGS@
 CFLGS = @GCC3_CFLAGS@
 CXXFLAGS = @CXXFLAGS@ $(CFLGS) @GCC3_CXXFLAGS@ -fno-rtti
 

build/autotools/configure.ac

@@ -35,6 +35,10 @@ if [[ "${ax_cv_prog_cc_stackprotectorstrong}" = "yes" ]]; then
 elif [[ "${ax_cv_prog_cc_stackprotector}" = "yes" ]]; then
   LDFLAGS="${LDFLAGS} -fstack-protector"
 fi
+CXX_FLAG_CHECK([DEBCXXFLAGS], [-Og], [Og])
+if [[ "${ax_cv_prog_cc_Og}" = "no" ]]; then
+  DEBCXXFLAGS="${DEBCXXFLAGS} -O0"
+fi
 CXX_FLAG_CHECK([DEBCXXFLAGS], [-fstack-protector-all], [stackprotectorall])
 
 EGG_CHECK_DEPMODE

configure

@@ -3400,6 +3400,66 @@ elif [ "${ax_cv_prog_cc_stackprotector}" = "yes" ]; then
   LDFLAGS="${LDFLAGS} -fstack-protector"
 fi
 
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler understands -Og" >&5
+$as_echo_n "checking whether the compiler understands -Og... " >&6; }
+if ${ax_cv_prog_cc_Og+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+    ac_ext=cpp
+ac_cpp='$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
+
+    ac_saved_flags="$CXXFLAGS"
+    CXXFLAGS="-Werror -Og"
+    cat build/confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end build/confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_prog_cc_Og="yes"
+else
+  ax_cv_prog_cc_Og="no"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+    CXXFLAGS="$ac_saved_flags"
+    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
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_prog_cc_Og" >&5
+$as_echo "$ax_cv_prog_cc_Og" >&6; }
+
+  if [ "$ax_cv_prog_cc_Og" = "yes" ]; then
+    DEBCXXFLAGS="$DEBCXXFLAGS -Og"
+  elif [ -n "" ]; then
+      cat << 'EOF' >&2
+configure: error:
+
+  Your OS or C++ compiler does not support -Og.
+  This compile flag is required.
+
+EOF
+    exit 1
+  fi
+
+if [ "${ax_cv_prog_cc_Og}" = "no" ]; then
+  DEBCXXFLAGS="${DEBCXXFLAGS} -O0"
+fi
+
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler understands -fstack-protector-all" >&5
 $as_echo_n "checking whether the compiler understands -fstack-protector-all... " >&6; }
 if ${ax_cv_prog_cc_stackprotectorall+:} false; then :