"Conflicting types" build failure(s) — clang 4.0.1

clang considers conflicting declarations as error while gcc just shows a warning
// clang  -c  foo.c
#include <stdio.h>
char *getline(int fd) { return NULL; }
PackageVersionSupposed error messageFull log Bug report
acedb 4.9.39+dfsg.02-1aqlparse.l:219:6: error: conflicting types for 'yyerror' Log
freefem 3.5.8-5.1setjmp.h:59:12: error: conflicting types for '__sigsetjmp' Log
gnats 4.1.0-3./gnats.h:140:12: error: conflicting types for 'asprintf' Log
jackeq 0.5.9-2.1main.c:251:6: error: conflicting types for 'getSettings' Log 753432
mokomaze 0.5.5+git8+dfsg0-4mainwindow.c:705:6: error: conflicting types for 'GoFallFixed' Log 753436
pccts 1.33MR33-6genmk.c:971:1: error: conflicting types for 'pclasses' Log 753538

6 errors