Re: [PATCH] include/linux/rbtree.h: move the declaration of c in rb_find_add()

[kernel test robot]

Hi Lin,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.3-rc7 next-20230417]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Lin-Chun-Yeh/include-linux-rbtree-h-move-the-declaration-of-c-in-rb_find_add/20230418-230031
patch link:    https://lore.kernel.org/r/20230418145712.20620-1-r09921093%40g.ntu.edu.tw
patch subject: [PATCH] include/linux/rbtree.h: move the declaration of c in rb_find_add()
config: arm-randconfig-r046-20230416 (https://download.01.org/0day-ci/archive/20230419/202304190118.H5o8xyuA-lkp@xxxxxxxxx/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 437b7602e4a998220871de78afcb020b9c14a661)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/intel-lab-lkp/linux/commit/9348e5c71c46a8d88c805acf5dd56c1785bc04e8
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Lin-Chun-Yeh/include-linux-rbtree-h-move-the-declaration-of-c-in-rb_find_add/20230418-230031
        git checkout 9348e5c71c46a8d88c805acf5dd56c1785bc04e8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/gpu/drm/tilcdc/ drivers/memstick/host/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202304190118.H5o8xyuA-lkp@xxxxxxxxx/

All error/warnings (new ones prefixed by >>):

   In file included from arch/arm/kernel/asm-offsets.c:11:
   In file included from include/linux/sched.h:20:
   In file included from include/linux/hrtimer.h:16:
>> include/linux/rbtree.h:231:7: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
                   int c = cmp(node, parent);
                       ^
   1 warning generated.
--
   In file included from drivers/memstick/host/r592.c:8:
   In file included from include/linux/module.h:14:
   In file included from include/linux/buildid.h:5:
   In file included from include/linux/mm_types.h:11:
>> include/linux/rbtree.h:231:7: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
                   int c = cmp(node, parent);
                       ^
   drivers/memstick/host/r592.c:47:13: warning: no previous prototype for function 'memstick_debug_get_tpc_name' [-Wmissing-prototypes]
   const char *memstick_debug_get_tpc_name(int tpc)
               ^
   drivers/memstick/host/r592.c:47:7: note: declare 'static' if the function is not intended to be used outside of this translation unit
   const char *memstick_debug_get_tpc_name(int tpc)
         ^
   static 
   2 warnings generated.
--
   In file included from drivers/gpu/drm/tilcdc/tilcdc_plane.c:7:
   In file included from include/drm/drm_atomic.h:31:
   In file included from include/drm/drm_crtc.h:30:
   In file included from include/drm/drm_modeset_lock.h:28:
   In file included from include/linux/stackdepot.h:25:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:22:
   In file included from include/linux/mm_types.h:11:
>> include/linux/rbtree.h:231:7: error: mixing declarations and code is incompatible with standards before C99 [-Werror,-Wdeclaration-after-statement]
                   int c = cmp(node, parent);
                       ^
   1 error generated.
--
   In file included from arch/arm/kernel/asm-offsets.c:11:
   In file included from include/linux/sched.h:20:
   In file included from include/linux/hrtimer.h:16:
>> include/linux/rbtree.h:231:7: warning: mixing declarations and code is incompatible with standards before C99 [-Wdeclaration-after-statement]
                   int c = cmp(node, parent);
                       ^
   1 warning generated.


vim +231 include/linux/rbtree.h

   212	
   213	/**
   214	 * rb_find_add() - find equivalent @node in @tree, or add @node
   215	 * @node: node to look-for / insert
   216	 * @tree: tree to search / modify
   217	 * @cmp: operator defining the node order
   218	 *
   219	 * Returns the rb_node matching @node, or NULL when no match is found and @node
   220	 * is inserted.
   221	 */
   222	static __always_inline struct rb_node *
   223	rb_find_add(struct rb_node *node, struct rb_root *tree,
   224		    int (*cmp)(struct rb_node *, const struct rb_node *))
   225	{
   226		struct rb_node **link = &tree->rb_node;
   227		struct rb_node *parent = NULL;
   228	
   229		while (*link) {
   230			parent = *link;
 > 231			int c = cmp(node, parent);
   232	
   233			if (c < 0)
   234				link = &parent->rb_left;
   235			else if (c > 0)
   236				link = &parent->rb_right;
   237			else
   238				return parent;
   239		}
   240	
   241		rb_link_node(node, parent, link);
   242		rb_insert_color(node, tree);
   243		return NULL;
   244	}
   245	

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