[3.10] pythonGH-99086: Fix -Wstrict-prototypes, -Wimplicit-function-declara… (python#99920)

[3.10] pythongh-99086: Fix -Wstrict-prototypes, -Wimplicit-function-declaration warnings in configure.ac (pythonGH-99406)

Follow up to 12078e7.
(cherry picked from commit e35ca41)

Co-authored-by: Sam James <[email protected]>

Author: thesamesam

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.

configure

@@ -5861,7 +5861,7 @@ 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 :
 
@@ -7593,7 +7593,7 @@ 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;
@@ -7649,7 +7649,7 @@ 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;
@@ -7699,7 +7699,7 @@ 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;
@@ -7749,7 +7749,7 @@ 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;
@@ -10060,7 +10060,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-int main()
+int main(void)
 {
     char s[16];
     int i, *p1, *p2;
@@ -10646,6 +10646,7 @@ $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); }
@@ -10947,7 +10948,7 @@ 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);
@@ -12256,7 +12257,7 @@ 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;
@@ -12305,7 +12306,7 @@ 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;
@@ -13266,7 +13267,7 @@ 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;
@@ -14493,7 +14494,7 @@ 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 */
@@ -15291,7 +15292,7 @@ else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-int main()
+int main(void)
 {
 	return (((-1)>>3 == -1) ? 0 : 1);
 }
@@ -15722,7 +15723,7 @@ else
 
 #include <stdlib.h>
 #include <unistd.h>
-int main()
+int main(void)
 {
 	int val1 = nice(1);
 	if (val1 != -1 && val1 == nice(2))
@@ -15765,7 +15766,7 @@ else
 #include <poll.h>
 #include <unistd.h>
 
-int main()
+int main(void)
 {
     struct pollfd poll_struct = { 42, POLLIN|POLLPRI|POLLOUT, 0 };
     int poll_test;
@@ -15823,7 +15824,7 @@ 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
@@ -16584,9 +16585,10 @@ 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);
@@ -16763,7 +16765,7 @@ 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)
@@ -16818,7 +16820,7 @@ else
               );
               return r;
             }
-            int main() {
+            int main(void) {
               int p = 8;
               if ((foo(&p) ? : p) != 6)
                 return 1;
@@ -16857,7 +16859,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
     #include <stdatomic.h>
     atomic_int int_var;
     atomic_uintptr_t uintptr_var;
-    int main() {
+    int main(void) {
       atomic_store_explicit(&int_var, 5, memory_order_relaxed);
       atomic_store_explicit(&uintptr_var, 0, memory_order_relaxed);
       int loaded_value = atomic_load_explicit(&int_var, memory_order_seq_cst);
@@ -16890,9 +16892,10 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
-    volatile int val = 1;
-    int main() {
-      __atomic_load_n(&val, __ATOMIC_SEQ_CST);
+    int val;
+    int main(void) {
+      __atomic_store_n(&val, 1, __ATOMIC_SEQ_CST);
+      (void)__atomic_load_n(&val, __ATOMIC_SEQ_CST);
       return 0;
     }
 
@@ -16949,7 +16952,7 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 
     #include <dirent.h>
 
-    int main() {
+    int main(void) {
       struct dirent entry;
       return entry.d_type == DT_UNKNOWN;
     }
@@ -16979,11 +16982,12 @@ 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;
@@ -17018,9 +17022,10 @@ 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;