On 11/18/2017 12:39 PM, Trond Myklebust wrote:
On Sat, 2017-11-18 at 12:19 -0500, Boris Ostrovsky wrote:
Commit fcd8843c406b46433857ae45e5e9d84b01a7d20b breaks on older
compilers which cannot process initializers for anonymous structures:
+const nfs4_stateid invalid_stateid = {
+ {
+ .seqid = cpu_to_be32(0xffffffffU),
+ .other = { 0 },
+ },
+ .type = NFS4_INVALID_STATEID_TYPE,
+};
/home/build/linux-linus/fs/nfs/nfs4state.c:74: error: unknown field
‘seqid’ specified in initializer
/home/build/linux-linus/fs/nfs/nfs4state.c:74: warning: missing
braces
around initializer
/home/build/linux-linus/fs/nfs/nfs4state.c:74: warning: (near
initialization for ‘invalid_stateid.<anonymous>.data’)
/home/build/linux-linus/fs/nfs/nfs4state.c:74: warning: overflow in
implicit constant conversion
/home/build/linux-linus/fs/nfs/nfs4state.c:75: error: unknown field
‘other’ specified in initializer
/home/build/linux-linus/fs/nfs/nfs4state.c:75: error: extra brace
group
at end of initializer
/home/build/linux-linus/fs/nfs/nfs4state.c:75: error: (near
initialization for ‘invalid_stateid.<anonymous>’)
/home/build/linux-linus/fs/nfs/nfs4state.c:75: warning: excess
elements
in union initializer
/home/build/linux-linus/fs/nfs/nfs4state.c:75: warning: (near
initialization for ‘invalid_stateid.<anonymous>’)
make[4]: *** [fs/nfs/nfs4state.o] Error 1
make[3]: *** [fs/nfs] Error 2
FC-64 <build@build-mk2:~> gcc --version
gcc (GCC) 4.4.4 20100503 (Red Hat 4.4.4-2)
A similar bug was fixed by e0714ec4f9efe7b86828b0dcc077fd8f5d8e5e91
but
I don't think the same approach can work here.
I don't have any setups with gcc 4.4.4. What is it expecting here? Is
it expecting an extra set of braces due to the anonymous "struct"?
No, that won't work (at least I couldn't get it to work) because the
solution from e0714ec4f9e assumes that the anonymous struct is the first
one in the enveloping struct.
It worked only if I (this is a small C program with equivalent structs):
struct nfs4_stateid_struct {
union {
//char data[4];
struct {
unsigned seqid;
char other[6];
} __attribute__ ((packed));
char data[4];
};
and then
const nfs4_stateid invalid_stateid = {
{
{.seqid = 0xffffffffU,
.other = { 0 } },
},
.type = NFS4_INVALID_STATEID_TYPE,
};
If I keep data[4] where it is now I get compiler error
an.c:35:20: error: field name not in record or union initializer
{.seqid = 0xffffffffU,
^
an.c:35:20: note: (near initialization for
'invalid_stateid.<anonymous>.data')
an.c:35:29: warning: overflow in implicit constant conversion [-Woverflow]
{.seqid = 0xffffffffU,
^~~~~~~~~~~
an.c:36:19: error: field name not in record or union initializer
.other = { 0 } },
^
an.c:36:19: note: (near initialization for
'invalid_stateid.<anonymous>.data')
an.c:36:19: warning: braces around scalar initializer
an.c:36:19: note: (near initialization for
'invalid_stateid.<anonymous>.data[1]')
I don't know if you want to change public header file just to get around
this problem.
-boris
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