gh-99086: Fix -Wstrict-prototypes, -Wimplicit-function-declaration warnings in configure.ac (#99406)

Follow up to 12078e78f6e4a21f344e4eaff529e1ff3b97734f.

3 files changed, 57 insertions, 48 deletions

diff --git a/Misc/NEWS.d/next/Build/2022-11-24-02-58-10.gh-issue-99086.DV_4Br.rst b/Misc/NEWS.d/next/Build/2022-11-24-02-58-10.gh-issue-99086.DV_4Br.rst
new file mode 100644
index 0000000..2dace16
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2022-11-24-02-58-10.gh-issue-99086.DV_4Br.rst
@@ -0,0 +1 @@
+Fix ``-Wimplicit-int``, ``-Wstrict-prototypes``, and ``-Wimplicit-function-declaration`` compiler warnings in :program:`configure` checks.
diff --git a/configure b/configure
index 047fd94..3f8daf9 100755
--- a/configure
+++ b/configure
@@ -6755,7 +6755,7 @@ if test "x$enable_profiling" = xyes; then
   CC="$CC -pg"
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
-int main() { return 0; }
+int main(void) { return 0; }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
 
@@ -9220,7 +9220,7 @@ else
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -9275,7 +9275,7 @@ else
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -9324,7 +9324,7 @@ else
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -9373,7 +9373,7 @@ else
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -12233,7 +12233,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-int main()
+int main(void)
 {
     char s[16];
     int i, *p1, *p2;
@@ -15042,6 +15042,7 @@ $as_echo_n "checking for pthread_create in -lpthread... " >&6; }
 /* end confdefs.h.  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <pthread.h>
 
 void * start_routine (void *arg) { exit (0); }
@@ -15352,7 +15353,7 @@ else
       void *foo(void *parm) {
         return NULL;
       }
-      int main() {
+      int main(void) {
         pthread_attr_t attr;
         pthread_t id;
         if (pthread_attr_init(&attr)) return (-1);
@@ -16954,7 +16955,7 @@ else
 
 #include <sys/stat.h>
 #include <unistd.h>
-int main(int argc, char*argv[])
+int main(int argc, char *argv[])
 {
   if(chflags(argv[0], 0) != 0)
     return 1;
@@ -17003,7 +17004,7 @@ else
 
 #include <sys/stat.h>
 #include <unistd.h>
-int main(int argc, char*argv[])
+int main(int argc, char *argv[])
 {
   if(lchflags(argv[0], 0) != 0)
     return 1;
@@ -19711,7 +19712,7 @@ else
 #include <sys/socket.h>
 #include <netinet/in.h>
 
-int main()
+int main(void)
 {
   int passive, gaierr, inet4 = 0, inet6 = 0;
   struct addrinfo hints, *ai, *aitop;
@@ -20908,7 +20909,7 @@ else
 
 #include <stdlib.h>
 #include <math.h>
-int main() {
+int main(void) {
     volatile double x, y, z;
     /* 1./(1-2**-53) -> 1+2**-52 (correct), 1.0 (double rounding) */
     x = 0.99999999999999989; /* 1-2**-53 */
@@ -21687,7 +21688,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-int main()
+int main(void)
 {
 	return (((-1)>>3 == -1) ? 0 : 1);
 }
@@ -22589,7 +22590,7 @@ else
 
 #include <stdlib.h>
 #include <unistd.h>
-int main()
+int main(void)
 {
 	int val1 = nice(1);
 	if (val1 != -1 && val1 == nice(2))
@@ -22631,7 +22632,7 @@ else
 #include <poll.h>
 #include <unistd.h>
 
-int main()
+int main(void)
 {
     struct pollfd poll_struct = { 42, POLLIN|POLLPRI|POLLOUT, 0 };
     int poll_test;
@@ -22688,7 +22689,7 @@ else
 extern char *tzname[];
 #endif
 
-int main()
+int main(void)
 {
 	/* Note that we need to ensure that not only does tzset(3)
 	   do 'something' with localtime, but it works as documented
@@ -24350,9 +24351,10 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
+#include <stddef.h>
 #include <stdio.h>
-#include<stdlib.h>
-int main() {
+#include <stdlib.h>
+int main(void) {
     size_t len = -1;
     const char *str = "text";
     len = mbstowcs(NULL, str, 0);
@@ -24552,7 +24554,7 @@ else
 #include <stdlib.h>
 #include <string.h>
 void foo(void *p, void *q) { memmove(p, q, 19); }
-int main() {
+int main(void) {
   char a[32] = "123456789000000000";
   foo(&a[9], a);
   if (strcmp(a, "123456789123456789000000000") != 0)
@@ -24607,7 +24609,7 @@ else
               );
               return r;
             }
-            int main() {
+            int main(void) {
               int p = 8;
               if ((foo(&p) ? : p) != 6)
                 return 1;
@@ -24650,7 +24652,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
     #include <stdatomic.h>
     atomic_int int_var;
     atomic_uintptr_t uintptr_var;
-    int main() {
+    int main(void) {
       atomic_store_explicit(&int_var, 5, memory_order_relaxed);
       atomic_store_explicit(&uintptr_var, 0, memory_order_relaxed);
       int loaded_value = atomic_load_explicit(&int_var, memory_order_seq_cst);
@@ -24691,7 +24693,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 
 
     int val;
-    int main() {
+    int main(void) {
       __atomic_store_n(&val, 1, __ATOMIC_SEQ_CST);
       (void)__atomic_load_n(&val, __ATOMIC_SEQ_CST);
       return 0;
@@ -24767,7 +24769,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 
     #include <dirent.h>
 
-    int main() {
+    int main(void) {
       struct dirent entry;
       return entry.d_type == DT_UNKNOWN;
     }
@@ -24805,11 +24807,12 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
+    #include <stddef.h>
     #include <unistd.h>
     #include <sys/syscall.h>
     #include <linux/random.h>
 
-    int main() {
+    int main(void) {
         char buffer[1];
         const size_t buflen = sizeof(buffer);
         const int flags = GRND_NONBLOCK;
@@ -24852,9 +24855,10 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
+    #include <stddef.h>
     #include <sys/random.h>
 
-    int main() {
+    int main(void) {
         char buffer[1];
         const size_t buflen = sizeof(buffer);
         const int flags = 0;
diff --git a/configure.ac b/configure.ac
index 19f12e8..734a4db 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1427,7 +1427,7 @@ AC_ARG_ENABLE(profiling,
 if test "x$enable_profiling" = xyes; then
   ac_save_cc="$CC"
   CC="$CC -pg"
-  AC_LINK_IFELSE([AC_LANG_SOURCE([[int main() { return 0; }]])],
+  AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void) { return 0; }]])],
     [],
     [enable_profiling=no])
   CC="$ac_save_cc"
@@ -2553,7 +2553,7 @@ AC_CACHE_CHECK([whether pthreads are available without options],
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -2586,7 +2586,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -2613,7 +2613,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -2640,7 +2640,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 
 void* routine(void* p){return NULL;}
 
-int main(){
+int main(void){
   pthread_t p;
   if(pthread_create(&p,NULL,routine,NULL)!=0)
     return 1;
@@ -3578,7 +3578,7 @@ esac
 # check for systems that require aligned memory access
 AC_CACHE_CHECK([aligned memory access is required], [ac_cv_aligned_required],
 [AC_RUN_IFELSE([AC_LANG_SOURCE([[
-int main()
+int main(void)
 {
     char s[16];
     int i, *p1, *p2;
@@ -4292,6 +4292,7 @@ yes
     AC_MSG_CHECKING([for pthread_create in -lpthread])
     AC_LINK_IFELSE([AC_LANG_PROGRAM([[
 #include <stdio.h>
+#include <stdlib.h>
 #include <pthread.h>
 
 void * start_routine (void *arg) { exit (0); }]], [[
@@ -4361,7 +4362,7 @@ if test "$posix_threads" = "yes"; then
       void *foo(void *parm) {
         return NULL;
       }
-      int main() {
+      int main(void) {
         pthread_attr_t attr;
         pthread_t id;
         if (pthread_attr_init(&attr)) return (-1);
@@ -4898,7 +4899,7 @@ AC_CACHE_CHECK([for chflags], [ac_cv_have_chflags], [dnl
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <sys/stat.h>
 #include <unistd.h>
-int main(int argc, char*argv[])
+int main(int argc, char *argv[])
 {
   if(chflags(argv[0], 0) != 0)
     return 1;
@@ -4920,7 +4921,7 @@ AC_CACHE_CHECK([for lchflags], [ac_cv_have_lchflags], [dnl
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <sys/stat.h>
 #include <unistd.h>
-int main(int argc, char*argv[])
+int main(int argc, char *argv[])
 {
   if(lchflags(argv[0], 0) != 0)
     return 1;
@@ -5196,7 +5197,7 @@ AS_VAR_IF([ac_cv_func_getaddrinfo], [yes], [
 #include <sys/socket.h>
 #include <netinet/in.h>
 
-int main()
+int main(void)
 {
   int passive, gaierr, inet4 = 0, inet6 = 0;
   struct addrinfo hints, *ai, *aitop;
@@ -5612,7 +5613,7 @@ CC="$CC $BASECFLAGS"
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <stdlib.h>
 #include <math.h>
-int main() {
+int main(void) {
     volatile double x, y, z;
     /* 1./(1-2**-53) -> 1+2**-52 (correct), 1.0 (double rounding) */
     x = 0.99999999999999989; /* 1-2**-53 */
@@ -5919,7 +5920,7 @@ fi],
 # or fills with zeros (like the Cray J90, according to Tim Peters).
 AC_CACHE_CHECK([whether right shift extends the sign bit], [ac_cv_rshift_extends_sign], [
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
-int main()
+int main(void)
 {
 	return (((-1)>>3 == -1) ? 0 : 1);
 }
@@ -6118,7 +6119,7 @@ AC_CACHE_CHECK([for broken nice()], [ac_cv_broken_nice], [
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <stdlib.h>
 #include <unistd.h>
-int main()
+int main(void)
 {
 	int val1 = nice(1);
 	if (val1 != -1 && val1 == nice(2))
@@ -6140,7 +6141,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <poll.h>
 #include <unistd.h>
 
-int main()
+int main(void)
 {
     struct pollfd poll_struct = { 42, POLLIN|POLLPRI|POLLOUT, 0 };
     int poll_test;
@@ -6176,7 +6177,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 extern char *tzname[];
 #endif
 
-int main()
+int main(void)
 {
 	/* Note that we need to ensure that not only does tzset(3)
 	   do 'something' with localtime, but it works as documented
@@ -6517,9 +6518,10 @@ AC_CHECK_TYPE(socklen_t,,
 
 AC_CACHE_CHECK([for broken mbstowcs], [ac_cv_broken_mbstowcs],
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
+#include <stddef.h>
 #include <stdio.h>
-#include<stdlib.h>
-int main() {
+#include <stdlib.h>
+int main(void) {
     size_t len = -1;
     const char *str = "text";
     len = mbstowcs(NULL, str, 0);
@@ -6646,7 +6648,7 @@ AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <stdlib.h>
 #include <string.h>
 void foo(void *p, void *q) { memmove(p, q, 19); }
-int main() {
+int main(void) {
   char a[32] = "123456789000000000";
   foo(&a[9], a);
   if (strcmp(a, "123456789123456789000000000") != 0)
@@ -6687,7 +6689,7 @@ if test "$ac_cv_gcc_asm_for_x87" = yes; then
               );
               return r;
             }
-            int main() {
+            int main(void) {
               int p = 8;
               if ((foo(&p) ? : p) != 6)
                 return 1;
@@ -6715,7 +6717,7 @@ AC_LINK_IFELSE(
     #include <stdatomic.h>
     atomic_int int_var;
     atomic_uintptr_t uintptr_var;
-    int main() {
+    int main(void) {
       atomic_store_explicit(&int_var, 5, memory_order_relaxed);
       atomic_store_explicit(&uintptr_var, 0, memory_order_relaxed);
       int loaded_value = atomic_load_explicit(&int_var, memory_order_seq_cst);
@@ -6736,7 +6738,7 @@ AC_LINK_IFELSE(
 [
   AC_LANG_SOURCE([[
     int val;
-    int main() {
+    int main(void) {
       __atomic_store_n(&val, 1, __ATOMIC_SEQ_CST);
       (void)__atomic_load_n(&val, __ATOMIC_SEQ_CST);
       return 0;
@@ -6777,7 +6779,7 @@ AC_LINK_IFELSE(
   AC_LANG_SOURCE([[
     #include <dirent.h>
 
-    int main() {
+    int main(void) {
       struct dirent entry;
       return entry.d_type == DT_UNKNOWN;
     }
@@ -6795,11 +6797,12 @@ AC_CACHE_CHECK([for the Linux getrandom() syscall], [ac_cv_getrandom_syscall], [
 AC_LINK_IFELSE(
 [
   AC_LANG_SOURCE([[
+    #include <stddef.h>
     #include <unistd.h>
     #include <sys/syscall.h>
     #include <linux/random.h>
 
-    int main() {
+    int main(void) {
         char buffer[1];
         const size_t buflen = sizeof(buffer);
         const int flags = GRND_NONBLOCK;
@@ -6822,9 +6825,10 @@ AC_CACHE_CHECK([for the getrandom() function], [ac_cv_func_getrandom], [
 AC_LINK_IFELSE(
 [
   AC_LANG_SOURCE([[
+    #include <stddef.h>
     #include <sys/random.h>
 
-    int main() {
+    int main(void) {
         char buffer[1];
         const size_t buflen = sizeof(buffer);
         const int flags = 0;