From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58897) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fRHFZ-0003cq-TK for qemu-devel@nongnu.org; Fri, 08 Jun 2018 09:16:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fRHFY-0002Fr-OV for qemu-devel@nongnu.org; Fri, 08 Jun 2018 09:16:17 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:51644 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fRHFY-0002FE-Hx for qemu-devel@nongnu.org; Fri, 08 Jun 2018 09:16:16 -0400 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Fri, 8 Jun 2018 14:16:04 +0100 Message-Id: <20180608131604.16826-4-berrange@redhat.com> In-Reply-To: <20180608131604.16826-1-berrange@redhat.com> References: <20180608131604.16826-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PATCH v3 3/3] glib: enforce the minimum required version and warn about old APIs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Eric Blake , Stefan Berger , Markus Armbruster , Peter Maydell , Paolo Bonzini , Stefan Hajnoczi , Thomas Huth , Peter Xu , Michael Roth , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Olaf Hering There are two useful macros that can be defined before including glib.h that are related to the min required glib version - GLIB_VERSION_MIN_REQUIRED When this is defined, if code uses an API that was deprecated in this version, or older, a compiler warning will be emitted. This alerts maintainers to update their code to whatever new replacement API is now recommended best practice. - GLIB_VERSION_MAX_ALLOWED When this is defined, if code uses an API that was introduced in a version that is newer than the declared version, a compiler warning will be emitted. This alerts maintainers if new code accidentally uses functionality that won't be available on some supported platforms. The GLIB_VERSION_MAX_ALLOWED constant makes it a bit harder to opt in to using specific new APIs with a GLIB_CHECK_VERSION conditional. To workaround this Pragmas can be used to temporarily turn off the -Wdeprecated-declarations compiler warning, while a static inline compat function is implemented. This workaround is illustrated with the implementation of the g_strv_contains method to satisfy the test suite. Signed-off-by: Daniel P. Berrang=C3=A9 --- include/glib-compat.h | 68 +++++++++++++++++++++++++++++++++++++++++++ tests/test-qga.c | 2 -- 2 files changed, 68 insertions(+), 2 deletions(-) diff --git a/include/glib-compat.h b/include/glib-compat.h index 3b340ab33c..fdf95a255d 100644 --- a/include/glib-compat.h +++ b/include/glib-compat.h @@ -16,8 +16,74 @@ #ifndef QEMU_GLIB_COMPAT_H #define QEMU_GLIB_COMPAT_H =20 +/* Ask for warnings for anything that was marked deprecated in + * the defined version, or before. It is a candidate for rewrite. + */ +#define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_40 + +/* Ask for warnings if code tries to use function that did not + * exist in the defined version. These risk breaking builds + */ +#define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_40 + +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wdeprecated-declarations" + #include =20 +/* + * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, all= owing + * use of functions from newer GLib via this compat header needs a littl= e + * trickery to prevent warnings being emitted. + * + * Consider a function from newer glib-X.Y that we want to use + * + * int g_foo(const char *wibble) + * + * We must define a static inline function with the same signature that = does + * what we need, but with a "_qemu" suffix e.g. + * + * static inline void g_foo_qemu(const char *wibble) + * { + * #if GLIB_CHECK_VERSION(X, Y, 0) + * g_foo(wibble) + * #else + * g_something_equivalent_in_older_glib(wibble); + * #endif + * } + * + * The #pragma at the top of this file turns off -Wdeprecated-declaratio= ns, + * ensuring this wrapper function impl doesn't trigger the compiler warn= ing + * about using too new glib APIs. Finally we can do + * + * #define g_foo(a) g_foo_qemu(a) + * + * So now the code elsewhere in QEMU, which *does* have the + * -Wdeprecated-declarations warning active, can call g_foo(...) as norm= al, + * without generating warnings. + */ + +static inline gboolean g_strv_contains_qemu(const gchar *const *strv, + const gchar *str) +{ +#if GLIB_CHECK_VERSION(2, 44, 0) + return g_strv_contains(strv, str); +#else + g_return_val_if_fail(strv !=3D NULL, FALSE); + g_return_val_if_fail(str !=3D NULL, FALSE); + + for (; *strv !=3D NULL; strv++) { + if (g_str_equal(str, *strv)) { + return TRUE; + } + } + + return FALSE; +#endif +} +#define g_strv_contains(a, b) g_strv_contains_qemu(a, b) + + #if defined(_WIN32) && !GLIB_CHECK_VERSION(2, 50, 0) /* * g_poll has a problem on Windows when using @@ -45,4 +111,6 @@ gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeo= ut); } while (0) #endif =20 +#pragma GCC diagnostic pop + #endif diff --git a/tests/test-qga.c b/tests/test-qga.c index 18e63cb533..30c9643257 100644 --- a/tests/test-qga.c +++ b/tests/test-qga.c @@ -744,12 +744,10 @@ static void test_qga_config(gconstpointer data) =20 strv =3D g_key_file_get_string_list(kf, "general", "blacklist", &n, = &error); g_assert_cmpint(n, =3D=3D, 2); -#if GLIB_CHECK_VERSION(2, 44, 0) g_assert_true(g_strv_contains((const char * const *)strv, "guest-ping")); g_assert_true(g_strv_contains((const char * const *)strv, "guest-get-time")); -#endif g_assert_no_error(error); g_strfreev(strv); =20 --=20 2.17.0