Adjust some warnings

Remove -Werror and add -fpermissive, this will allow to compile C code with
a GNU C++ compiler.

Ignore warnings as our code use some feature like empty arrays.

Remove warnings not available in C++.

Bump GLIB_VERSION_MAX_ALLOWED to reduce the warning, looks like the
GLib headers for C++ are not able to handle them correctly.

Signed-off-by: Frediano Ziglio <fziglio@redhat.com>

configure.ac

@@ -52,6 +52,7 @@ AC_PROG_CXX
 AC_LANG_PUSH([C++])
 m4_ifndef([AX_CXX_COMPILE_STDCXX_11], [m4_fatal([Missing AX_CXX_COMPILE_STDCXX_11, install autoconf-archive])])
 AX_CXX_COMPILE_STDCXX_11
+AX_APPEND_COMPILE_FLAGS([-fno-exceptions -fno-rtti -fno-check-new --no_rtti])
 AC_LANG_POP([C++])
 
 AC_CHECK_HEADERS([sys/time.h execinfo.h linux/sockios.h pthread_np.h])
@@ -187,7 +188,7 @@ GLIB2_REQUIRED=2.38
 GLIB2_ENCODED_VERSION="GLIB_VERSION_2_38"
 PKG_CHECK_MODULES([GLIB2], [glib-2.0 >= $GLIB2_REQUIRED gio-2.0 >= $GLIB2_REQUIRED])
 GLIB2_CFLAGS="$GLIB2_CFLAGS -DGLIB_VERSION_MIN_REQUIRED=$GLIB2_ENCODED_VERSION \
-  -DGLIB_VERSION_MAX_ALLOWED=$GLIB2_ENCODED_VERSION"
+  -DGLIB_VERSION_MAX_ALLOWED=GLIB_VERSION_2_60"
 AS_VAR_APPEND([SPICE_REQUIRES], [" glib-2.0 >= $GLIB2_REQUIRED gio-2.0 >= $GLIB2_REQUIRED"])
 
 PKG_CHECK_MODULES([GOBJECT2], [gobject-2.0 >= $GLIB2_REQUIRED])
@@ -262,7 +263,9 @@ AS_IF([test "$enable_statistics" = "yes"],
 dnl ===========================================================================
 dnl check compiler flags
 
+AC_LANG_PUSH([C++])
 SPICE_COMPILE_WARNINGS
+AC_LANG_POP([C++])
 LIBVIRT_LINKER_RELRO
 LIBVIRT_LINKER_NO_INDIRECT
 

m4/spice-compile-warnings.m4

@@ -68,6 +68,28 @@ AC_DEFUN([SPICE_COMPILE_WARNINGS],[
     # decl mess with  gtk/generated_*.c
     dontwarn="$dontwarn -Wmissing-declarations"
 
+    # Stuff that C++ won't allow. Turn them back on later
+    dontwarn="$dontwarn -Wdesignated-init"
+    dontwarn="$dontwarn -Wdiscarded-array-qualifiers"
+    dontwarn="$dontwarn -Wdiscarded-qualifiers"
+    dontwarn="$dontwarn -Wimplicit"
+    dontwarn="$dontwarn -Wimplicit-function-declaration"
+    dontwarn="$dontwarn -Wimplicit-int"
+    dontwarn="$dontwarn -Wincompatible-pointer-types"
+    dontwarn="$dontwarn -Wint-conversion"
+    dontwarn="$dontwarn -Wjump-misses-init"
+    dontwarn="$dontwarn -Wmissing-parameter-type"
+    dontwarn="$dontwarn -Wmissing-prototypes"
+    dontwarn="$dontwarn -Wnested-externs"
+    dontwarn="$dontwarn -Wold-style-declaration"
+    dontwarn="$dontwarn -Wold-style-definition"
+    dontwarn="$dontwarn -Woverride-init"
+    dontwarn="$dontwarn -Wpointer-sign"
+    dontwarn="$dontwarn -Wpointer-to-int-cast"
+    dontwarn="$dontwarn -Wstrict-prototypes"
+    dontwarn="$dontwarn -Wsuggest-final-methods"
+    dontwarn="$dontwarn -Wsuggest-final-types"
+
     # Get all possible GCC warnings
     gl_MANYWARN_ALL_GCC([maybewarn])
 
@@ -131,9 +153,28 @@ AC_DEFUN([SPICE_COMPILE_WARNINGS],[
     then
       gl_WARN_ADD([-Werror])
     fi
-    WARN_CXXFLAGS=$WARN_CFLAGS
+
+    save_CFLAGS="$WARN_CFLAGS"
+
+    # -fpermissive to allow compile C with C++
+    gl_WARN_ADD([-fpermissive])
+
+    # -Wno-suggest-final-methods and -Wno-suggest-final-types to avoid warnings for optimization
+    gl_WARN_ADD([-Wno-suggest-final-methods])
+    gl_WARN_ADD([-Wno-suggest-final-types])
+
+    # -Wno-array-bounds to avoid checks for array with 0 size
+    gl_WARN_ADD([-Wno-array-bounds])
+
+    # -Wno-narrowing to allow cast from -1 to unsigned (used in some initialization)
+    gl_WARN_ADD([-Wno-narrowing])
+
+    gl_WARN_ADD([-Wno-missing-field-initializers])
+
+    WARN_CXXFLAGS="$WARN_CFLAGS"
     AC_SUBST([WARN_CXXFLAGS])
 
+    WARN_CFLAGS="$save_CFLAGS"
     WARN_LDFLAGS=$WARN_CFLAGS
     AC_SUBST([WARN_CFLAGS])
     AC_SUBST([WARN_LDFLAGS])

meson.build

@@ -191,6 +191,18 @@ add_project_arguments(compiler.get_supported_arguments(spice_server_global_cflag
                       language : 'c')
 
 spice_server_global_cxxflags = spice_server_global_cflags
+spice_server_global_cxxflags += [
+  '-fno-exceptions',
+  '-fno-rtti',
+  '--no_rtti',
+  '-fpermissive',
+  '-Wno-suggest-final-methods',
+  '-Wno-suggest-final-types',
+  '-Wno-array-bounds',
+  '-Wno-narrowing',
+  '-Wno-missing-field-initializers',
+  '-Wno-deprecated-declarations',
+]
 add_project_arguments(cxx_compiler.get_supported_arguments(spice_server_global_cxxflags),
                       language : 'cpp')
 

server/red-client.c

@@ -293,7 +293,7 @@ gboolean red_client_add_channel(RedClient *client, RedChannelClient *rcc, GError
 
     // first must be the main one
     if (!client->mcc) {
-        client->mcc = g_object_ref(rcc);
+        client->mcc = (MainChannelClient *) g_object_ref(rcc);
         spice_assert(MAIN_CHANNEL_CLIENT(rcc) != NULL);
     }
     client->channels = g_list_prepend(client->channels, rcc);