Fixed main() prototypes in auto tests.

Future releases of GCC are planning to remove[0] default support for
some old features that were removed from C99 but GCC still accepts.

We can test for these changes by using the following -Werror=
directives

  -Werror=implicit-int
  -Werror=implicit-function-declaration
  -Werror=int-conversion
  -Werror=strict-prototypes
  -Werror=old-style-definition

Doing so revealed an issue with the auto/ tests in that the test
programs always define main as

  int main()

rather than

  int main(void)

which results in a bunch of errors like

build/autotest.c:3:23: error: function declaration isn't a prototype [-Werror=strict-prototypes]
    3 |                   int main() {
      |                       ^~~~
build/autotest.c: In function 'main':
build/autotest.c:3:23: error: old-style function definition [-Werror=old-style-definition]

The fix was easy, it only required fixing the main prototype with

  find -type f -exec sed -i 's/int main() {/int main(void) {/g' {} \;

Regardless of these upcoming GCC changes, this is probably a good thing
to do anyway for correctness.

[0]: https://fedoraproject.org/wiki/Changes/PortingToModernC

Link: <https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/CJXKTLXJUPZ4F2C2VQOTNMEA5JAUPMBD/>
Link: <https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/6SGHPHPAXKCVJ6PUZ57WVDQ5TDBVIRMF/>
Reviewed-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/auto/atomic b/auto/atomic
index 31259fc5..f99adf7e 100644
--- a/auto/atomic
+++ b/auto/atomic
@@ -10,7 +10,7 @@ nxt_feature_name=NXT_HAVE_GCC_ATOMIC
 nxt_feature_run=yes
 nxt_feature_incs=
 nxt_feature_libs=
-nxt_feature_test="int main() {
+nxt_feature_test="int main(void) {
                       long  n = 0;
 
                       if (!__sync_bool_compare_and_swap(&n, 0, 3))
@@ -44,7 +44,7 @@ if [ $nxt_found = no ]; then
     nxt_feature_libs=
     nxt_feature_test="#include <atomic.h>
 
-                      int main() {
+                      int main(void) {
                           ulong_t  n = 0;
 
                           if (atomic_cas_ulong(&n, 0, 3) != 0)
@@ -70,7 +70,7 @@ fi
 if [ $nxt_found = no ]; then
 
     if [ $NXT_64BIT = 1 ]; then
-        nxt_feature_test="int main() {
+        nxt_feature_test="int main(void) {
                               long  n = 0;
                               long  o = 0;
 
@@ -87,7 +87,7 @@ if [ $nxt_found = no ]; then
                               return 0;
                           }"
     else
-        nxt_feature_test="int main() {
+        nxt_feature_test="int main(void) {
                               int  n = 0;
                               int  o = 0;