[PATCH 2/2] misc: Replace zero-length arrays with flexible array member (manual)

[Philippe Mathieu-Daudé]

Description copied from Linux kernel commit from Gustavo A. R. Silva
(see [3]):

--v-- description start --v--

  The current codebase makes use of the zero-length array language
  extension to the C90 standard, but the preferred mechanism to
  declare variable-length types such as these ones is a flexible
  array member [1], introduced in C99:

  struct foo {
      int stuff;
      struct boo array[];
  };

  By making use of the mechanism above, we will get a compiler
  warning in case the flexible array does not occur last in the
  structure, which will help us prevent some kind of undefined
  behavior bugs from being unadvertenly introduced [2] to the
  Linux codebase from now on.

--^-- description end --^--

Do the similar housekeeping in the QEMU codebase (which uses
C99 since commit 7be41675f7cb).

All these instances of code were found with the help of the
following command (then manual analysis):

  git grep -F '[0];'

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76497732932f
[3] 
https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=17642a2fbd2c1

Inspired-by: Gustavo A. R. Silva <address@hidden>
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 docs/interop/vhost-user.rst       | 4 ++--
 block/qed.h                       | 2 +-
 include/hw/acpi/acpi-defs.h       | 4 ++--
 include/hw/boards.h               | 2 +-
 include/hw/s390x/event-facility.h | 2 +-
 include/hw/s390x/sclp.h           | 8 ++++----
 block/vmdk.c                      | 2 +-
 hw/char/sclpconsole-lm.c          | 2 +-
 hw/char/sclpconsole.c             | 2 +-
 hw/s390x/virtio-ccw.c             | 2 +-
 target/s390x/ioinst.c             | 2 +-
 11 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 401652397c..3b1b6602c7 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -568,7 +568,7 @@ For split virtqueue, queue region can be implemented as:
       uint16_t used_idx;
 
       /* Used to track the state of each descriptor in descriptor table */
-      DescStateSplit desc[0];
+      DescStateSplit desc[];
   } QueueRegionSplit;
 
 To track inflight I/O, the queue region should be processed as follows:
@@ -690,7 +690,7 @@ For packed virtqueue, queue region can be implemented as:
       uint8_t padding[7];
 
       /* Used to track the state of each descriptor fetched from descriptor 
ring */
-      DescStatePacked desc[0];
+      DescStatePacked desc[];
   } QueueRegionPacked;
 
 To track inflight I/O, the queue region should be processed as follows:
diff --git a/block/qed.h b/block/qed.h
index 42c115d822..87428ba00e 100644
--- a/block/qed.h
+++ b/block/qed.h
@@ -103,7 +103,7 @@ typedef struct {
 } QEMU_PACKED QEDHeader;
 
 typedef struct {
-    uint64_t offsets[0];            /* in bytes */
+    uint64_t offsets[];             /* in bytes */
 } QEDTable;
 
 /* The L2 cache is a simple write-through cache for L2 structures */
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index 19f7ba7b70..c13327fa78 100644
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -152,7 +152,7 @@ typedef struct AcpiSerialPortConsoleRedirection
  */
 struct AcpiRsdtDescriptorRev1 {
     ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
-    uint32_t table_offset_entry[0];  /* Array of pointers to other */
+    uint32_t table_offset_entry[];  /* Array of pointers to other */
     /* ACPI tables */
 } QEMU_PACKED;
 typedef struct AcpiRsdtDescriptorRev1 AcpiRsdtDescriptorRev1;
@@ -162,7 +162,7 @@ typedef struct AcpiRsdtDescriptorRev1 
AcpiRsdtDescriptorRev1;
  */
 struct AcpiXsdtDescriptorRev2 {
     ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
-    uint64_t table_offset_entry[0];  /* Array of pointers to other */
+    uint64_t table_offset_entry[];  /* Array of pointers to other */
     /* ACPI tables */
 } QEMU_PACKED;
 typedef struct AcpiXsdtDescriptorRev2 AcpiXsdtDescriptorRev2;
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 9bc42dfb22..c96120d15f 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -71,7 +71,7 @@ typedef struct CPUArchId {
  */
 typedef struct {
     int len;
-    CPUArchId cpus[0];
+    CPUArchId cpus[];
 } CPUArchIdList;
 
 /**
diff --git a/include/hw/s390x/event-facility.h 
b/include/hw/s390x/event-facility.h
index bdc32a3c09..700a610f33 100644
--- a/include/hw/s390x/event-facility.h
+++ b/include/hw/s390x/event-facility.h
@@ -122,7 +122,7 @@ typedef struct MDBO {
 
 typedef struct MDB {
     MdbHeader header;
-    MDBO mdbo[0];
+    MDBO mdbo[];
 } QEMU_PACKED MDB;
 
 typedef struct SclpMsg {
diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index c54413b78c..cd7b24359f 100644
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -132,7 +132,7 @@ typedef struct ReadInfo {
     uint16_t highest_cpu;
     uint8_t  _reserved5[124 - 122];     /* 122-123 */
     uint32_t hmfai;
-    struct CPUEntry entries[0];
+    struct CPUEntry entries[];
 } QEMU_PACKED ReadInfo;
 
 typedef struct ReadCpuInfo {
@@ -142,7 +142,7 @@ typedef struct ReadCpuInfo {
     uint16_t nr_standby;            /* 12-13 */
     uint16_t offset_standby;        /* 14-15 */
     uint8_t reserved0[24-16];       /* 16-23 */
-    struct CPUEntry entries[0];
+    struct CPUEntry entries[];
 } QEMU_PACKED ReadCpuInfo;
 
 typedef struct ReadStorageElementInfo {
@@ -151,7 +151,7 @@ typedef struct ReadStorageElementInfo {
     uint16_t assigned;
     uint16_t standby;
     uint8_t _reserved0[16 - 14]; /* 14-15 */
-    uint32_t entries[0];
+    uint32_t entries[];
 } QEMU_PACKED ReadStorageElementInfo;
 
 typedef struct AttachStorageElement {
@@ -159,7 +159,7 @@ typedef struct AttachStorageElement {
     uint8_t _reserved0[10 - 8];  /* 8-9 */
     uint16_t assigned;
     uint8_t _reserved1[16 - 12]; /* 12-15 */
-    uint32_t entries[0];
+    uint32_t entries[];
 } QEMU_PACKED AttachStorageElement;
 
 typedef struct AssignStorage {
diff --git a/block/vmdk.c b/block/vmdk.c
index 20e909d997..8466051bc9 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -187,7 +187,7 @@ typedef struct VmdkMetaData {
 typedef struct VmdkGrainMarker {
     uint64_t lba;
     uint32_t size;
-    uint8_t  data[0];
+    uint8_t  data[];
 } QEMU_PACKED VmdkGrainMarker;
 
 enum {
diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c
index c420dc066e..2b5f37b6a2 100644
--- a/hw/char/sclpconsole-lm.c
+++ b/hw/char/sclpconsole-lm.c
@@ -31,7 +31,7 @@
 typedef struct OprtnsCommand {
     EventBufferHeader header;
     MDMSU message_unit;
-    char data[0];
+    char data[];
 } QEMU_PACKED OprtnsCommand;
 
 /* max size for line-mode data in 4K SCCB page */
diff --git a/hw/char/sclpconsole.c b/hw/char/sclpconsole.c
index 1fa124dab9..5c7664905e 100644
--- a/hw/char/sclpconsole.c
+++ b/hw/char/sclpconsole.c
@@ -25,7 +25,7 @@
 
 typedef struct ASCIIConsoleData {
     EventBufferHeader ebh;
-    char data[0];
+    char data[];
 } QEMU_PACKED ASCIIConsoleData;
 
 /* max size for ASCII data in 4K SCCB page */
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 50cf95b781..64f928fc7d 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -193,7 +193,7 @@ typedef struct VirtioThinintInfo {
 typedef struct VirtioRevInfo {
     uint16_t revision;
     uint16_t length;
-    uint8_t data[0];
+    uint8_t data[];
 } QEMU_PACKED VirtioRevInfo;
 
 /* Specify where the virtqueues for the subchannel are in guest memory. */
diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
index c437a1d8c6..0e840cc579 100644
--- a/target/s390x/ioinst.c
+++ b/target/s390x/ioinst.c
@@ -347,7 +347,7 @@ typedef struct ChscResp {
     uint16_t len;
     uint16_t code;
     uint32_t param;
-    char data[0];
+    char data[];
 } QEMU_PACKED ChscResp;
 
 #define CHSC_MIN_RESP_LEN 0x0008
-- 
2.21.1