"No support of nested C function" build failure(s) — clang 12.0.1

clang rejects inner functions while gcc accepts them.
void foo() {

     void bar() {

     }

}
PackageVersionSupposed error messageFull log Bug report
bluez 5.61-1profiles/midi/midi.c:61:75: error: function definition is not allowed here Log
bogl 0.1.18-17bogl-font.c:84:3: error: function definition is not allowed here Log 758063
ell 0.44-1ell/tls.c:1895:2: error: function definition is not allowed here Log
eurephia 1.1.0-6.1eurephiadm.c:203:47: error: function definition is not allowed here Log
growl-for-linux 0.8.5-8balloon.c:160:72: error: function definition is not allowed here Log
grsync 1.3.0-1callbacks.c:44:64: error: function definition is not allowed here Log
gst-plugins-espeak 0.5.0-1espeak.c:211:59: error: function definition is not allowed here Log
iwd 1.18-1ell/tls.c:1895:2: error: function definition is not allowed here Log
kraptor 0.0.20040403+ds-2src/game.c:416:3: error: function definition is not allowed here Log 750370
mandos 1.8.14-1plugins.d/password-prompt.c:124:51: error: function definition is not allowed here Log 750516
netplug 1.2.9.2-3if_info.c:295:37: error: function definition is not allowed here Log 750789
ppp 2.4.9-1+1eap-tls.c:520:13: error: function definition is not allowed here Log
ratpoints 1:2.1.3-1./sturm.c:176:5: error: function definition is not allowed here Log
rsh-redone 85-3rlogin.c:388:30: error: function definition is not allowed here Log 750957
wtdbg2 2.5-8./wtdbg.h:1755:2: error: function definition is not allowed here Log
xneur 0.20.0-3text.c:292:25: error: function definition is not allowed here Log 751542

16 errors