[PATCH 0/2] linux-user: Fix a pair of -Wextra warnings

[PATCH 0/2] linux-user: Fix a pair of -Wextra warnings

[Philippe Mathieu-Daudé]

Philippe Mathieu-Daudé (2):
  linux-user/syscall: Silent -Wmissing-field-initializers warnings
  linux-user/signal: Silent -Winitializer-overrides warnings

 linux-user/signal-common.h |  2 +-
 linux-user/syscall.c       | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

-- 
2.38.1

[PATCH 1/2] linux-user/syscall: Silent -Wmissing-field-initializers warnings

[Philippe Mathieu-Daudé]

Silent when compiling with -Wextra:

  In file included from ../../linux-user/syscall.c:5742:
  ../linux-user/ioctls.h:694:3: warning: missing field 'access' initializer [-Wmissing-field-initializers]
  IOCTL_IGNORE(TIOCSTART)
  ^
  ../linux-user/syscall.c:5741:31: note: expanded from macro 'IOCTL_IGNORE'
    { TARGET_ ## cmd, 0, #cmd },
                              ^
  ../linux-user/syscall.c:5743:13: warning: missing field 'name' initializer [-Wmissing-field-initializers]
    { 0, 0, },
            ^
  ../linux-user/syscall.c:12949:44: warning: missing field 'sigev_signo' initializer [-Wmissing-field-initializers]
        struct sigevent host_sevp = { {0}, }, *phost_sevp = NULL;
                                           ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 linux-user/syscall.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1f8c10f8ef..f3ab6bf5a6 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5738,9 +5738,9 @@ IOCTLEntry ioctl_entries[] = {
 #define IOCTL_SPECIAL(cmd, access, dofn, ...)                      \
     { TARGET_ ## cmd, cmd, #cmd, access, dofn, {  __VA_ARGS__ } },
 #define IOCTL_IGNORE(cmd) \
-    { TARGET_ ## cmd, 0, #cmd },
+    { TARGET_ ## cmd, 0, #cmd, 0, NULL, { } },
 #include "ioctls.h"
-    { 0, 0, },
+    { /* end of list */ }
 };
 
 /* ??? Implement proper locking for ioctls.  */
@@ -12946,7 +12946,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
     {
         /* args: clockid_t clockid, struct sigevent *sevp, timer_t *timerid */
 
-        struct sigevent host_sevp = { {0}, }, *phost_sevp = NULL;
+        struct sigevent host_sevp = { }, *phost_sevp = NULL;
 
         int clkid = arg1;
         int timer_index = next_free_host_timer();
@@ -12993,7 +12993,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
             ret = -TARGET_EINVAL;
         } else {
             timer_t htimer = g_posix_timers[timerid];
-            struct itimerspec hspec_new = {{0},}, hspec_old = {{0},};
+            struct itimerspec hspec_new = { }, hspec_old = { };
 
             if (target_to_host_itimerspec(&hspec_new, arg3)) {
                 return -TARGET_EFAULT;
@@ -13019,7 +13019,7 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
             ret = -TARGET_EINVAL;
         } else {
             timer_t htimer = g_posix_timers[timerid];
-            struct itimerspec hspec_new = {{0},}, hspec_old = {{0},};
+            struct itimerspec hspec_new = { }, hspec_old = { };
 
             if (target_to_host_itimerspec64(&hspec_new, arg3)) {
                 return -TARGET_EFAULT;
-- 
2.38.1

[PATCH 2/2] linux-user/signal: Silent -Winitializer-overrides warnings

[Philippe Mathieu-Daudé]

The target SIGIOT signal is sometimes aliased with SIGABRT,
producing the following warning when compiling with -Wextra:

  ../linux-user/signal.c:57:9: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
          MAKE_SIGNAL_LIST
          ^~~~~~~~~~~~~~~~
  ../linux-user/signal-common.h:165:9: note: expanded from macro 'MAKE_SIGNAL_LIST'
          MAKE_SIG_ENTRY_SIGIOT
          ^~~~~~~~~~~~~~~~~~~~~
  ../linux-user/signal-common.h:128:41: note: expanded from macro 'MAKE_SIG_ENTRY_SIGIOT'
  #define MAKE_SIG_ENTRY_SIGIOT           MAKE_SIG_ENTRY(SIGIOT)
                                          ^~~~~~~~~~~~~~~~~~~~~~
  ../linux-user/signal.c:56:41: note: expanded from macro 'MAKE_SIG_ENTRY'
  #define MAKE_SIG_ENTRY(sig)     [sig] = TARGET_##sig,
                                          ^~~~~~~~~~~~
  <scratch space>:81:1: note: expanded from here
  TARGET_SIGIOT
  ^~~~~~~~~~~~~
  ../linux-user/sh4/../generic/signal.h:26:34: note: expanded from macro 'TARGET_SIGIOT'
  #define TARGET_SIGIOT            6
                                   ^
  <scratch space>:55:1: note: expanded from here
  TARGET_SIGABRT
  ^~~~~~~~~~~~~~
  ../linux-user/sh4/../generic/signal.h:25:34: note: expanded from macro 'TARGET_SIGABRT'
  #define TARGET_SIGABRT           6
                                   ^

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 linux-user/signal-common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
index 3e2dc604c2..a168ea4851 100644
--- a/linux-user/signal-common.h
+++ b/linux-user/signal-common.h
@@ -124,7 +124,7 @@ static inline void finish_sigsuspend_mask(int ret)
 #define MAKE_SIG_ENTRY_SIGSTKFLT
 #endif
 
-#if defined(SIGIOT) && defined(TARGET_SIGIOT)
+#if defined(SIGIOT) && defined(TARGET_SIGIOT) && TARGET_SIGABRT != TARGET_SIGIOT
 #define MAKE_SIG_ENTRY_SIGIOT           MAKE_SIG_ENTRY(SIGIOT)
 #else
 #define MAKE_SIG_ENTRY_SIGIOT
-- 
2.38.1

Re: [PATCH 2/2] linux-user/signal: Silent -Winitializer-overrides warnings

[Peter Maydell]

On Tue, 20 Dec 2022 at 14:43, Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
>
> The target SIGIOT signal is sometimes aliased with SIGABRT,
> producing the following warning when compiling with -Wextra:
>
>   ../linux-user/signal.c:57:9: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
>           MAKE_SIGNAL_LIST
>           ^~~~~~~~~~~~~~~~
>   ../linux-user/signal-common.h:165:9: note: expanded from macro 'MAKE_SIGNAL_LIST'
>           MAKE_SIG_ENTRY_SIGIOT
>           ^~~~~~~~~~~~~~~~~~~~~
>   ../linux-user/signal-common.h:128:41: note: expanded from macro 'MAKE_SIG_ENTRY_SIGIOT'
>   #define MAKE_SIG_ENTRY_SIGIOT           MAKE_SIG_ENTRY(SIGIOT)
>                                           ^~~~~~~~~~~~~~~~~~~~~~
>   ../linux-user/signal.c:56:41: note: expanded from macro 'MAKE_SIG_ENTRY'
>   #define MAKE_SIG_ENTRY(sig)     [sig] = TARGET_##sig,
>                                           ^~~~~~~~~~~~
>   <scratch space>:81:1: note: expanded from here
>   TARGET_SIGIOT
>   ^~~~~~~~~~~~~
>   ../linux-user/sh4/../generic/signal.h:26:34: note: expanded from macro 'TARGET_SIGIOT'
>   #define TARGET_SIGIOT            6
>                                    ^
>   <scratch space>:55:1: note: expanded from here
>   TARGET_SIGABRT
>   ^~~~~~~~~~~~~~
>   ../linux-user/sh4/../generic/signal.h:25:34: note: expanded from macro 'TARGET_SIGABRT'
>   #define TARGET_SIGABRT           6
>                                    ^
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>  linux-user/signal-common.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h
> index 3e2dc604c2..a168ea4851 100644
> --- a/linux-user/signal-common.h
> +++ b/linux-user/signal-common.h
> @@ -124,7 +124,7 @@ static inline void finish_sigsuspend_mask(int ret)
>  #define MAKE_SIG_ENTRY_SIGSTKFLT
>  #endif
>
> -#if defined(SIGIOT) && defined(TARGET_SIGIOT)
> +#if defined(SIGIOT) && defined(TARGET_SIGIOT) && TARGET_SIGABRT != TARGET_SIGIOT
>  #define MAKE_SIG_ENTRY_SIGIOT           MAKE_SIG_ENTRY(SIGIOT)
>  #else
>  #define MAKE_SIG_ENTRY_SIGIOT

This suppresses the array entry in the case where TARGET_SIGABRT ==
TARGET_SIGIOT,
but the compiler error is I think complaining about the case where
host SIGABRT == SIGIOT.

The MAKE_SIG_ENTRY macros are used to construct both the host-to-target signal
table in signal.c and also a target-signal-to-string table in strace.c;
so whether you want to check "target signals the same?" or "host signals
the same?" to suppress the overriding entry varies depending on which table.

However, this is all a bit moot because:
 (1) we deliberately do not enable the -Winitializer-overrides
     warning, because it produces false positives on the various
     cases where we want to use the coding pattern "initialize a range
     first, then override some specific members within it"
 (2) There is no Linux architecture where SIGIOT is not a synonym
     for SIGABRT, so the right thing to do here is just to
     delete MAKE_SIG_ENTRY_SIGIOT entirely.

thanks
-- PMM