[PATCH v4] build: update DPDK to use C11 standard

[Bruce Richardson <bruce.richardson@intel.com>]

As previously announced, DPDK 23.11 will require a C11 supporting
compiler and will use the C11 standard in all builds.

Forcing use of the C standard, rather than the standard with
GNU extensions, means that some posix definitions which are not in
the C standard are unavailable by default. We fix this by ensuring
the correct defines or cflags are passed to the components that
need them.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
---
V4:
* pass cflags to the structure and definition checks in mlx* drivers
  to ensure posix definitions - as well as C-standard ones - are
  available.

V3:
* remove (now unneeded) use of -std=gnu99 in failsafe net driver.

V2:
* Resubmit now that 23.11-rc0 patch applied
* Add _POSIX_C_SOURCE macro to eal_common_errno.c to get POSIX
  definition of strerror_r() with c11 standard.
---
 doc/guides/linux_gsg/sys_reqs.rst      |  3 ++-
 doc/guides/rel_notes/deprecation.rst   | 18 ------------------
 doc/guides/rel_notes/release_23_11.rst | 17 +++++++++++++++++
 drivers/common/mlx5/linux/meson.build  |  5 +++--
 drivers/net/failsafe/meson.build       |  1 -
 drivers/net/mlx4/meson.build           |  4 ++--
 lib/eal/common/eal_common_errno.c      |  1 +
 meson.build                            |  1 +
 8 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/doc/guides/linux_gsg/sys_reqs.rst b/doc/guides/linux_gsg/sys_reqs.rst
index dfeaf4e1c5..13be715933 100644
--- a/doc/guides/linux_gsg/sys_reqs.rst
+++ b/doc/guides/linux_gsg/sys_reqs.rst
@@ -27,7 +27,8 @@ Compilation of the DPDK
     The setup commands and installed packages needed on various systems may be different.
     For details on Linux distributions and the versions tested, please consult the DPDK Release Notes.
 
-*   General development tools including a supported C compiler such as gcc (version 4.9+) or clang (version 3.4+),
+*   General development tools including a C compiler supporting the C11 standard,
+    including standard atomics, for example: GCC (version 5.0+) or Clang (version 3.6+),
     and ``pkg-config`` or ``pkgconf`` to be used when building end-user binaries against DPDK.
 
     * For RHEL/Fedora systems these can be installed using ``dnf groupinstall "Development Tools"``
diff --git a/doc/guides/rel_notes/deprecation.rst b/doc/guides/rel_notes/deprecation.rst
index 494b401cda..cc939d3c67 100644
--- a/doc/guides/rel_notes/deprecation.rst
+++ b/doc/guides/rel_notes/deprecation.rst
@@ -17,24 +17,6 @@ Other API and ABI deprecation notices are to be posted below.
 Deprecation Notices
 -------------------
 
-* C Compiler: From DPDK 23.11 onwards,
-  building DPDK will require a C compiler which supports the C11 standard,
-  including support for C11 standard atomics.
-
-  More specifically, the requirements will be:
-
-  * Support for flag "-std=c11" (or similar)
-  * __STDC_NO_ATOMICS__ is *not defined* when using c11 flag
-
-  Please note:
-
-  * C11, including standard atomics, is supported from GCC version 5 onwards,
-    and is the default language version in that release
-    (Ref: https://gcc.gnu.org/gcc-5/changes.html)
-  * C11 is the default compilation mode in Clang from version 3.6,
-    which also added support for standard atomics
-    (Ref: https://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html)
-
 * build: Enabling deprecated libraries (``flow_classify``, ``kni``)
   won't be possible anymore through the use of the ``disable_libs`` build option.
   A new build option for deprecated libraries will be introduced instead.
diff --git a/doc/guides/rel_notes/release_23_11.rst b/doc/guides/rel_notes/release_23_11.rst
index 6b4dd21fd0..c8b9ed456c 100644
--- a/doc/guides/rel_notes/release_23_11.rst
+++ b/doc/guides/rel_notes/release_23_11.rst
@@ -20,6 +20,23 @@ DPDK Release 23.11
       ninja -C build doc
       xdg-open build/doc/guides/html/rel_notes/release_23_11.html
 
+* Build Requirements: From DPDK 23.11 onwards,
+  building DPDK will require a C compiler which supports the C11 standard,
+  including support for C11 standard atomics.
+
+  More specifically, the requirements will be:
+
+  * Support for flag "-std=c11" (or similar)
+  * __STDC_NO_ATOMICS__ is *not defined* when using c11 flag
+
+  Please note:
+
+  * C11, including standard atomics, is supported from GCC version 5 onwards,
+    and is the default language version in that release
+    (Ref: https://gcc.gnu.org/gcc-5/changes.html)
+  * C11 is the default compilation mode in Clang from version 3.6,
+    which also added support for standard atomics
+    (Ref: https://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html)
 
 New Features
 ------------
diff --git a/drivers/common/mlx5/linux/meson.build b/drivers/common/mlx5/linux/meson.build
index 15edc13041..b3a64547c5 100644
--- a/drivers/common/mlx5/linux/meson.build
+++ b/drivers/common/mlx5/linux/meson.build
@@ -231,11 +231,12 @@ if  libmtcr_ul_found
 endif
 
 foreach arg:has_sym_args
-    mlx5_config.set(arg[0], cc.has_header_symbol(arg[1], arg[2], dependencies: libs))
+    mlx5_config.set(arg[0], cc.has_header_symbol(arg[1], arg[2], dependencies: libs, args: cflags))
 endforeach
 foreach arg:has_member_args
     file_prefix = '#include <' + arg[1] + '>'
-    mlx5_config.set(arg[0], cc.has_member(arg[2], arg[3], prefix : file_prefix, dependencies: libs))
+    mlx5_config.set(arg[0],
+            cc.has_member(arg[2], arg[3], prefix : file_prefix, dependencies: libs, args: cflags))
 endforeach
 
 # Build Glue Library
diff --git a/drivers/net/failsafe/meson.build b/drivers/net/failsafe/meson.build
index 6013e13722..c1d361083b 100644
--- a/drivers/net/failsafe/meson.build
+++ b/drivers/net/failsafe/meson.build
@@ -7,7 +7,6 @@ if is_windows
     subdir_done()
 endif
 
-cflags += '-std=gnu99'
 cflags += '-D_DEFAULT_SOURCE'
 cflags += '-D_XOPEN_SOURCE=700'
 cflags += '-pedantic'
diff --git a/drivers/net/mlx4/meson.build b/drivers/net/mlx4/meson.build
index a038c1ec1b..3c5ee24186 100644
--- a/drivers/net/mlx4/meson.build
+++ b/drivers/net/mlx4/meson.build
@@ -103,12 +103,12 @@ has_sym_args = [
 config = configuration_data()
 foreach arg:has_sym_args
     config.set(arg[0], cc.has_header_symbol(arg[1], arg[2],
-        dependencies: libs))
+        dependencies: libs, args: cflags))
 endforeach
 foreach arg:has_member_args
     file_prefix = '#include <' + arg[1] + '>'
     config.set(arg[0], cc.has_member(arg[2], arg[3],
-        prefix: file_prefix, dependencies: libs))
+        prefix: file_prefix, dependencies: libs, args: cflags))
 endforeach
 configure_file(output : 'mlx4_autoconf.h', configuration : config)
 
diff --git a/lib/eal/common/eal_common_errno.c b/lib/eal/common/eal_common_errno.c
index ef8f782abb..b30e2f0ad4 100644
--- a/lib/eal/common/eal_common_errno.c
+++ b/lib/eal/common/eal_common_errno.c
@@ -4,6 +4,7 @@
 
 /* Use XSI-compliant portable version of strerror_r() */
 #undef _GNU_SOURCE
+#define _POSIX_C_SOURCE 200809L
 
 #include <stdio.h>
 #include <string.h>
diff --git a/meson.build b/meson.build
index 39cb73846d..70b54f0c98 100644
--- a/meson.build
+++ b/meson.build
@@ -9,6 +9,7 @@ project('DPDK', 'c',
         license: 'BSD',
         default_options: [
             'buildtype=release',
+            'c_std=c11',
             'default_library=static',
             'warning_level=2',
         ],
-- 
2.39.2