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[Qemu-devel] [PATCH v2 2/3] glib: enforce the minimum required version a
From: |
Daniel P . Berrangé |
Subject: |
[Qemu-devel] [PATCH v2 2/3] glib: enforce the minimum required version and warn about old APIs |
Date: |
Wed, 6 Jun 2018 18:32:32 +0100 |
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. Berrangé <address@hidden>
---
include/glib-compat.h | 67 ++++++++++++++++++++++++
tests/docker/dockerfiles/centos6.docker | 30 -----------
tests/docker/dockerfiles/min-glib.docker | 8 ---
tests/test-qga.c | 2 -
4 files changed, 67 insertions(+), 40 deletions(-)
delete mode 100644 tests/docker/dockerfiles/centos6.docker
delete mode 100644 tests/docker/dockerfiles/min-glib.docker
diff --git a/include/glib-compat.h b/include/glib-compat.h
index 3b340ab33c..cfc3cba751 100644
--- a/include/glib-compat.h
+++ b/include/glib-compat.h
@@ -16,8 +16,73 @@
#ifndef QEMU_GLIB_COMPAT_H
#define QEMU_GLIB_COMPAT_H
+/* 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 <glib.h>
+/*
+ * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
+ * use of functions from newer GLib via this compat header needs a little
+ * 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-declarations,
+ * ensuring this wrapper function impl doesn't trigger the compiler warning
+ * 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 normal,
+ * 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 != NULL, FALSE);
+ g_return_val_if_fail(str != NULL, FALSE);
+
+ for (; *strv != 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 +110,6 @@ gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
} while (0)
#endif
+_Pragma("GCC diagnostic pop")
+
#endif
diff --git a/tests/docker/dockerfiles/centos6.docker
b/tests/docker/dockerfiles/centos6.docker
deleted file mode 100644
index ad24319582..0000000000
--- a/tests/docker/dockerfiles/centos6.docker
+++ /dev/null
@@ -1,30 +0,0 @@
-FROM centos:6
-RUN yum install -y epel-release centos-release-xen
-ENV PACKAGES \
- bison \
- bzip2-devel \
- ccache \
- csnappy-devel \
- flex \
- g++ \
- gcc \
- gettext \
- git \
- glib2-devel \
- libepoxy-devel \
- libfdt-devel \
- librdmacm-devel \
- lzo-devel \
- make \
- mesa-libEGL-devel \
- mesa-libgbm-devel \
- pixman-devel \
- SDL-devel \
- spice-glib-devel \
- spice-server-devel \
- tar \
- vte-devel \
- xen-devel \
- zlib-devel
-RUN yum install -y $PACKAGES
-RUN rpm -q $PACKAGES | sort > /packages.txt
diff --git a/tests/docker/dockerfiles/min-glib.docker
b/tests/docker/dockerfiles/min-glib.docker
deleted file mode 100644
index f2eed97d35..0000000000
--- a/tests/docker/dockerfiles/min-glib.docker
+++ /dev/null
@@ -1,8 +0,0 @@
-FROM centos:6
-RUN yum install -y \
- tar gettext git make gcc g++ \
- zlib-devel SDL-devel pixman-devel \
- epel-release
-RUN yum install -y libfdt-devel ccache
-RUN yum downgrade -y
http://vault.centos.org/6.0/os/x86_64/Packages/glib2-2.22.5-5.el6.x86_64.rpm
-RUN yum install -y
http://vault.centos.org/6.0/os/x86_64/Packages/glib2-devel-2.22.5-5.el6.x86_64.rpm
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)
strv = g_key_file_get_string_list(kf, "general", "blacklist", &n, &error);
g_assert_cmpint(n, ==, 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);
--
2.17.0
[Qemu-devel] [PATCH v2 2/3] glib: enforce the minimum required version and warn about old APIs,
Daniel P . Berrangé <=
[Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Daniel P . Berrangé, 2018/06/06
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Philippe Mathieu-Daudé, 2018/06/06
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Peter Maydell, 2018/06/06
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Peter Xu, 2018/06/06
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Markus Armbruster, 2018/06/07
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Peter Xu, 2018/06/07
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Daniel P . Berrangé, 2018/06/07
- Re: [Qemu-devel] [PATCH v2 3/3] util: remove redundant include of glib.h, Peter Xu, 2018/06/07