On Mon, Jan 21, 2019 at 04:38:25PM +0100, Peter Krempa wrote:
> On Mon, Jan 21, 2019 at 15:13:21 +0000, Richard W.M. Jones wrote:
> > GCC 9 gives pages of errors like:
> >
> > qemumonitorjsontest.c: In function 'mymain':
> > qemumonitorjsontest.c:2904:9: error: jump skips variable initialization [-Werror=jump-misses-init]
> > 2904 | goto cleanup;
> > | ^~~~
> > qemumonitorjsontest.c:3111:2: note: label 'cleanup' defined here
> > 3111 | cleanup:
> > | ^~~~~~~
> > qemumonitorjsontest.c:2920:54: note: '({anonymous})' declared here
> > 2920 | simpleFunc = (testQemuMonitorJSONSimpleFuncData) {.xmlopt = driver.xmlopt, \
> > | ^
> > qemumonitorjsontest.c:3008:5: note: in expansion of macro 'DO_TEST_GEN'
> > 3008 | DO_TEST_GEN(qemuMonitorJSONBlockdevMediumInsert);
> > | ^~~~~~~~~~~
> >
> > By moving the cleanup section up near the top of the function we can
> > avoid this. I think a better way might be to disable the warning.
> > ---
> > tests/qemumonitorjsontest.c | 10 ++++++----
> > 1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/tests/qemumonitorjsontest.c b/tests/qemumonitorjsontest.c
> > index 1a8a31717f..299c5f0cbe 100644
> > --- a/tests/qemumonitorjsontest.c
> > +++ b/tests/qemumonitorjsontest.c
> > @@ -2900,8 +2900,12 @@ mymain(void)
> >
> > if (!(qapiData.schema = testQEMUSchemaLoad())) {
> > VIR_TEST_VERBOSE("failed to load qapi schema\n");
> > - ret = -1;
> > - goto cleanup;
> > + cleanup:
> > + VIR_FREE(metaschemastr);
> > + virJSONValueFree(metaschema);
> > + virHashFree(qapiData.schema);
> > + qemuTestDriverFree(&driver);
> > + return -1;
> > }
> >
> > #define DO_TEST(name) \
> > @@ -3098,7 +3102,6 @@ mymain(void)
> > if (!(metaschema = testQEMUSchemaGetLatest()) ||
> > !(metaschemastr = virJSONValueToString(metaschema, false))) {
> > VIR_TEST_VERBOSE("failed to load latest qapi schema\n");
> > - ret = -1;
> > goto cleanup;
>
> We generally avoid jumps back. Also cleanup really should be at the end.
>
> Wouldn't be enough just to memset the few structs at the beginning?
No, this appears to be another GCC regression. IMHO the following should
not warn, yet it does:
$ cat demo.c
#include <stdlib.h>
struct demo {
const char *cmd;
};
int main(void)
{
struct demo demo = {0};
if ((demo.cmd = getenv("FOO")) == NULL) {
goto cleanup;
}
demo = (struct demo) { .cmd = "foo" };
cleanup:
return 0;
}
$ gcc -Wjump-misses-init -o demo demo.c
demo.c: In function ‘main’:
demo.c:13:5: warning: jump skips variable initialization [-Wjump-misses-init]
13 | goto cleanup;
| ^~~~
demo.c:18:2: note: label ‘cleanup’ defined here
18 | cleanup:
| ^~~~~~~
demo.c:16:24: note: ‘({anonymous})’ declared here
16 | demo = (struct demo) { .cmd = "foo" };
| ^
This doesn't appear to be reported to GCC upstream yet
Regards,
Daniel
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