treewide: uapi: Replace zero-length arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare
having a dynamically sized set of trailing elements in a structure.
Kernel code should always use “flexible array members”[1] for these
cases. The older style of one-element or zero-length arrays should
no longer be used[2].

This code was transformed with the help of Coccinelle:
(linux-5.19-rc2$ spatch --jobs $(getconf _NPROCESSORS_ONLN) --sp-file script.cocci --include-headers --dir . > output.patch)

@@
identifier S, member, array;
type T1, T2;
@@

struct S {
  ...
  T1 member;
  T2 array[
- 0
  ];
};

-fstrict-flex-arrays=3 is coming and we need to land these changes
to prevent issues like these in the short future:

../fs/minix/dir.c:337:3: warning: 'strcpy' will always overflow; destination buffer has size 0,
but the source string has length 2 (including NUL byte) [-Wfortify-source]
		strcpy(de3->name, ".");
		^

Since these are all [0] to [] changes, the risk to UAPI is nearly zero. If
this breaks anything, we can use a union with a new member name.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/78
Build-tested-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/62b675ec.wKX6AOZ6cbE71vtF%25lkp@intel.com/
Acked-by: Dan Williams <dan.j.williams@intel.com> # For ndctl.h
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/uapi/sound/firewire.h b/include/uapi/sound/firewire.h
index 39cf6eb75940..3532ac7046d7 100644
--- a/include/uapi/sound/firewire.h
+++ b/include/uapi/sound/firewire.h
@@ -38,11 +38,11 @@ struct snd_efw_transaction {
 	__be32 category;
 	__be32 command;
 	__be32 status;
-	__be32 params[0];
+	__be32 params[];
 };
 struct snd_firewire_event_efw_response {
 	unsigned int type;
-	__be32 response[0];	/* some responses */
+	__be32 response[];	/* some responses */
 };
 
 struct snd_firewire_event_digi00x_message {
@@ -63,7 +63,7 @@ struct snd_firewire_tascam_change {
 
 struct snd_firewire_event_tascam_control {
 	unsigned int type;
-	struct snd_firewire_tascam_change changes[0];
+	struct snd_firewire_tascam_change changes[];
 };
 
 struct snd_firewire_event_motu_register_dsp_change {