On Mon, 9 Apr 2018 16:28:12 +0100 Bruce Richardson <bruce.richard...@intel.com> wrote:
> On Mon, Apr 09, 2018 at 03:51:10PM +0100, Singh, Jasvinder wrote: > > > > > -----Original Message----- > > > From: Richardson, Bruce > > > Sent: Monday, April 9, 2018 2:09 PM > > > To: Singh, Jasvinder <jasvinder.si...@intel.com> > > > Cc: dev@dpdk.org; Dumitrescu, Cristian <cristian.dumitre...@intel.com> > > > Subject: Re: [dpdk-dev] [PATCH] table: fix build error with gcc 8 > > > > > > On Mon, Apr 09, 2018 at 01:49:48PM +0100, Jasvinder Singh wrote: > > > > Fix build error with gcc 8.0 due to cast between function types. > > > > Fixes: 5a80bf0ae613 ("table: add cuckoo hash") > > > > > > > > Signed-off-by: Jasvinder Singh <jasvinder.si...@intel.com> > > > > > > What's the actual error message? Why do the types not match? > > > > > > /Bruce > > > > Error log is captured below; > > > > CC rte_table_hash_cuckoo.o > > /librte_table/rte_table_hash_cuckoo.c: In function > > 'rte_table_hash_cuckoo_create': > > /librte_table/rte_table_hash_cuckoo.c:110:16: error: cast between > > incompatible > > function types from 'rte_table_hash_op_hash' {aka 'long unsigned int > > (*)(void *, void *, unsigned int, long unsigned int)'} > > to 'uint32_t (*)(const void *, uint32_t, uint32_t)' {aka 'unsigned int > > (*)(const void *, unsigned int, unsigned int)'} > > [-Werror=cast-function-type] > > .hash_func = (rte_hash_function) p->f_hash, > > ^ > > cc1: all warnings being treated as errors > > > Even if the compiler isn't complaining now, how can that cast work? Looking > at the error message given, it appears there are two big issues: > > 1. The expected function call takes 3 parameters: > (const void *, uint32_t, uint32_t), > but you are giving it a function that takes 4 parameters: > (void *, void *, unsigned int, long unsigned int) > 2. The return type expected is "unsigned int", but you are giving a > function returning "long unsigned int". On 32-bit systems, these are > going to be the same size, but on 64-bit, they will be different. > Similarly for the last function argument. > > Is the error message correct? Yes. the current code is working only by luck