[newlib-cygwin] Cygwin: cygserver: build with -Wimplicit-fallthrough=5

[newlib-cygwin] Cygwin: cygserver: build with -Wimplicit-fallthrough=5

[Ken Brown]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=225d376b70f92bbb68b57b928a29044ab3c30acf

commit 225d376b70f92bbb68b57b928a29044ab3c30acf
Author: Ken Brown <kbrown@cornell.edu>
Date:   Fri Aug 7 09:48:28 2020 -0400

    Cygwin: cygserver: build with -Wimplicit-fallthrough=5
    
    Define the pseudo keyword 'fallthrough' in woutsup.h to support this.

Diff:
---
 winsup/cygserver/Makefile.in   | 2 +-
 winsup/cygserver/bsd_helper.cc | 2 +-
 winsup/cygserver/bsd_mutex.cc  | 2 +-
 winsup/cygserver/woutsup.h     | 2 ++
 4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/winsup/cygserver/Makefile.in b/winsup/cygserver/Makefile.in
index bbdfc25fb..70f38233c 100644
--- a/winsup/cygserver/Makefile.in
+++ b/winsup/cygserver/Makefile.in
@@ -16,7 +16,7 @@ export CXX:=@CXX@
 
 CFLAGS:=@CFLAGS@
 override CXXFLAGS=@CXXFLAGS@
-override CXXFLAGS+=-MMD -Wimplicit-fallthrough=4 -Werror -D__OUTSIDE_CYGWIN__ -DSYSCONFDIR="\"$(sysconfdir)\""
+override CXXFLAGS+=-MMD -Wimplicit-fallthrough=5 -Werror -D__OUTSIDE_CYGWIN__ -DSYSCONFDIR="\"$(sysconfdir)\""
 
 include ${srcdir}/../Makefile.common
 
diff --git a/winsup/cygserver/bsd_helper.cc b/winsup/cygserver/bsd_helper.cc
index ecc90e117..38639647e 100644
--- a/winsup/cygserver/bsd_helper.cc
+++ b/winsup/cygserver/bsd_helper.cc
@@ -120,7 +120,7 @@ ipcexit_hookthread (const LPVOID param)
     {
       case WAIT_OBJECT_0:
         /* Cygserver shutdown. */
-	/*FALLTHRU*/
+	fallthrough;
       case WAIT_OBJECT_0 + 1:
         /* Process exited.  Call semexit_myhook to handle SEM_UNDOs for the
 	   exiting process and shmexit_myhook to keep track of shared
diff --git a/winsup/cygserver/bsd_mutex.cc b/winsup/cygserver/bsd_mutex.cc
index 13c5f90e8..0cda87a5b 100644
--- a/winsup/cygserver/bsd_mutex.cc
+++ b/winsup/cygserver/bsd_mutex.cc
@@ -326,7 +326,7 @@ _msleep (void *ident, struct mtx *mtx, int priority,
         break;
       case WAIT_OBJECT_0 + 1:	/* Shutdown event (triggered by wakeup_all). */
         priority |= PDROP;
-	/*FALLTHRU*/
+	fallthrough;
       case WAIT_OBJECT_0 + 2:	/* The dependent process has exited. */
 	debug ("msleep process exit or shutdown for %d", td->td_proc->winpid);
 	ret = EIDRM;
diff --git a/winsup/cygserver/woutsup.h b/winsup/cygserver/woutsup.h
index 272f978c0..7b799f156 100644
--- a/winsup/cygserver/woutsup.h
+++ b/winsup/cygserver/woutsup.h
@@ -12,6 +12,8 @@ details. */
 #error "woutsup.h is not for code being compiled inside the dll"
 #endif
 
+#define fallthrough	__attribute__((__fallthrough__))
+
 #ifndef _WIN32_WINNT
 #define _WIN32_WINNT 0x0500
 #endif