[newlib-cygwin] [ARM] Make _kill() a noreturn function.

[Richard Earnshaw <rearnsha@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=8a7536e91d7dc361adf9b66c4e14e9596c0b0ccc

commit 8a7536e91d7dc361adf9b66c4e14e9596c0b0ccc
Author: Christophe Lyon <christophe.lyon@linaro.org>
Date:   Mon Oct 1 15:52:42 2018 +0000

    [ARM] Make _kill() a noreturn function.
    
    AngelSWI_Reason_ReportException does not return accoring to the ARM
    documentation, so it is valid to mark _kill() as noreturn.  This way,
    the compiler does not warn about _exit() returning a value despite
    being noreturn.
    
    2018-10-01  Christophe Lyon  <christophe.lyon@linaro.org>
    
    	* libgloss/arm/_exit.c (_exit): Declare _kill() as noreturn.
    	* libgloss/arm/_exit.c (_kill): Likewise. Remove the return
    	statements.
    	* newlib/libc/sys/arm/syscalls.c (_kill): Likewise..

Diff:
---
 libgloss/arm/_exit.c           |  2 +-
 libgloss/arm/_kill.c           |  8 +++++---
 newlib/libc/sys/arm/syscalls.c | 13 ++++++++-----
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/libgloss/arm/_exit.c b/libgloss/arm/_exit.c
index ca2d21c..4a071df 100644
--- a/libgloss/arm/_exit.c
+++ b/libgloss/arm/_exit.c
@@ -1,6 +1,6 @@
 #include <_ansi.h>
 
-int _kill (int, int);
+int _kill (int, int) __attribute__((__noreturn__));
 void _exit (int);
 
 void
diff --git a/libgloss/arm/_kill.c b/libgloss/arm/_kill.c
index 278ded7..34a6ffd 100644
--- a/libgloss/arm/_kill.c
+++ b/libgloss/arm/_kill.c
@@ -2,7 +2,7 @@
 #include <signal.h>
 #include "swi.h"
 
-int _kill (int, int);
+int _kill (int, int) __attribute__((__noreturn__));
 
 int
 _kill (int pid, int sig)
@@ -41,12 +41,14 @@ _kill (int pid, int sig)
 
 #if SEMIHOST_V2
 if (_has_ext_exit_extended ())
-  return do_AngelSWI (insn, block);
+  do_AngelSWI (insn, block);
 else
 #endif
-  return do_AngelSWI (insn, (void*)block[0]);
+  do_AngelSWI (insn, (void*)block[0]);
 
 #else
   asm ("swi %a0" :: "i" (SWI_Exit));
 #endif
+
+  __builtin_unreachable();
 }
diff --git a/newlib/libc/sys/arm/syscalls.c b/newlib/libc/sys/arm/syscalls.c
index d2a65cb..87ddca7 100644
--- a/newlib/libc/sys/arm/syscalls.c
+++ b/newlib/libc/sys/arm/syscalls.c
@@ -30,7 +30,7 @@ int	_stat		(const char *, struct stat *);
 int	_fstat		(int, struct stat *);
 void *	_sbrk		(ptrdiff_t);
 pid_t	_getpid		(void);
-int	_kill		(int, int);
+int	_kill		(int, int) __attribute__((__noreturn__));
 void	_exit		(int);
 int	_close		(int);
 int	_swiclose	(int);
@@ -432,15 +432,18 @@ _kill (int pid, int sig)
   /* Note: The pid argument is thrown away.  */
   switch (sig) {
 	  case SIGABRT:
-		  return do_AngelSWI (AngelSWI_Reason_ReportException,
-				  (void *) ADP_Stopped_RunTimeError);
+		  do_AngelSWI (AngelSWI_Reason_ReportException,
+			       (void *) ADP_Stopped_RunTimeError);
+		  __builtin_unreachable();
 	  default:
-		  return do_AngelSWI (AngelSWI_Reason_ReportException,
-				  (void *) ADP_Stopped_ApplicationExit);
+		  do_AngelSWI (AngelSWI_Reason_ReportException,
+			       (void *) ADP_Stopped_ApplicationExit);
   }
 #else
   asm ("swi %a0" :: "i" (SWI_Exit));
 #endif
+
+  __builtin_unreachable();
 }
 
 void