implicit-fallthrough warnings in sinproc/sws

[andreasstieger]

A number of switch case fall-through warnings are triggered. This is gcc13-13.2.1,

[   55s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/inproc/sinproc.c: In function ‘nn_sinproc_shutdown_events’:
[   55s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/inproc/sinproc.c:224:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
[   55s]   224 |         switch (type) {
[   55s]       |         ^~~~~~
[   55s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/inproc/sinproc.c:242:5: note: here
[   55s]   242 |     case NN_SINPROC_SRC_PEER:
[   55s]       |     ^~~~
[   55s] make[2]: Leaving directory '/home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/build'

If this fall-through is intended, in case of src == NN_FSM_ACTION and type != NN_FSM_STOP, please mark it with /* FALLTHRU */ or __attribute__ ((fallthrough)), or [[fallthrough]]; in C++17.

The second one is a 500 line switch-case statement which, which has some fall-through cases that may or may not be intended.

[   56s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/ws/sws.c: In function ‘nn_sws_handler’:
[   56s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/ws/sws.c:974:9: warning: this statement may fall through [-Wimplicit-fallthrough=]
[   56s]   974 |         switch (src) {
[   56s]       |         ^~~~~~
[   56s] /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/src/transports/ws/sws.c:1495:5: note: here
[   56s]  1495 |     case NN_SWS_STATE_CLOSING_CONNECTION:
[   56s]       |     ^~~~
[   56s] make[2]: Leaving directory '/home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/build'
[   56s] make[2]: Entering directory '/home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/build'

Full flags are:

[   44s] + /usr/bin/cmake /home/abuild/rpmbuild/BUILD/nanomsg-1.2.1/. '-GUnix Makefiles' -DCMAKE_INSTALL_PREFIX:PATH=/usr -DCMAKE_INSTALL_BINDIR:PATH=bin -DCMAKE_INSTALL_SBINDIR:PATH=sbin -DCMAKE_INSTALL_LIBEXECDIR:PATH=libexec -DCMAKE_INSTALL_SYSCONFDIR:PATH=etc -DCMAKE_INSTALL_SHAREDSTATEDIR:PATH=/var/lib -DCMAKE_INSTALL_LOCALSTATEDIR:PATH=var -DCMAKE_INSTALL_RUNSTATEDIR:PATH=run -DCMAKE_INSTALL_LIBDIR:PATH=lib64 -DCMAKE_INSTALL_INCLUDEDIR:PATH=include -DCMAKE_INSTALL_DATAROOTDIR:PATH=share -DINCLUDE_INSTALL_DIR:PATH=/usr/include -DLIB_INSTALL_DIR:PATH=/usr/lib64 -DSYSCONF_INSTALL_DIR:PATH=/etc -DSHARE_INSTALL_PREFIX:PATH=/usr/share -DCMAKE_BUILD_TYPE=RelWithDebInfo '-DCMAKE_C_FLAGS=-O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g' '-DCMAKE_CXX_FLAGS=-O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g' '-DCMAKE_Fortran_FLAGS=-O2 -Wall -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g' '-DCMAKE_EXE_LINKER_FLAGS=-flto=auto -Wl,--as-needed -Wl,--no-undefined -Wl,-z,now' '-DCMAKE_MODULE_LINKER_FLAGS=-flto=auto -Wl,--as-needed' '-DCMAKE_SHARED_LINKER_FLAGS=-flto=auto -Wl,--as-needed -Wl,--no-undefined -Wl,-z,now' -DLIB_SUFFIX=64 -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -DBUILD_SHARED_LIBS:BOOL=ON -DBUILD_STATIC_LIBS:BOOL=OFF -DCMAKE_COLOR_MAKEFILE:BOOL=OFF -DCMAKE_INSTALL_DO_STRIP:BOOL=OFF -DCMAKE_MODULES_INSTALL_DIR=/usr/lib64/cmake/nanomsg

[andreasstieger]

Previously rejected in #1056