https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114266
Bug ID: 114266
Summary: No -pedantic diagnostic for zero-sized array in
compound literals
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: daniel.lundin.mail at gmail dot com
Target Milestone: ---
(int[]){}; produces no diagnostics with -std=c23 -pedantic.
Empty initalizer lists are OK under -std=c23 and -std=gnu so that's not the
problem. gcc correctly gives a diagnostic for that in -std=c17 -pedantic mode.
Zero-sized arrays should however give a diagnostic in -std=cxx -pedantic mode.
Prior to C23 this was not really a problem as we would get a diagnostic for the
empty initializer list. But now this non-conforming C compiles cleanly even
with -pedantic set.
A diagnostic similar to the one given in clang would be good:
warning: zero size arrays are an extension [-Wzero-length-array]
As I understand it, gcc did have -Wzero-length-array in the past but removed
it? See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94428. The options
-Wstrict-flex-arrays -fstrict-flex-arrays seem to have no effect (and my
example isn't a flexible array member but a compound literal).
