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>

5 files changed, 12 insertions, 12 deletions

diff --git a/auto/modules/java b/auto/modules/java
index e8137217..691060b3 100644
--- a/auto/modules/java
+++ b/auto/modules/java
@@ -191,7 +191,7 @@ nxt_feature_libs="${NXT_JAVA_LDFLAGS}"
 nxt_feature_test="
     #include <jni.h>
 
-    int main() {
+    int main(void) {
         JNI_CreateJavaVM(NULL, NULL, NULL);
         return 0;
     }"
diff --git a/auto/modules/perl b/auto/modules/perl
index e9d7e109..2daebd0d 100644
--- a/auto/modules/perl
+++ b/auto/modules/perl
@@ -79,7 +79,7 @@ if /bin/sh -c "$NXT_PERL -MConfig -e 'print \"Perl version: \",
 
         static PerlInterpreter *my_perl;
 
-        int main() {
+        int main(void) {
             char argv[] = \"\\0-e\\00\";
             char *embedding[] = { &argv[0], &argv[1], &argv[4] };
 
@@ -124,7 +124,7 @@ nxt_feature_test="
     #include <EXTERN.h>
     #include <perl.h>
 
-    int main() {
+    int main(void) {
         printf(\"%s\", PERL_VERSION_STRING);
         return 0;
     }"
diff --git a/auto/modules/php b/auto/modules/php
index 7d224ec1..f0ecb709 100644
--- a/auto/modules/php
+++ b/auto/modules/php
@@ -131,7 +131,7 @@ nxt_feature_libs="${NXT_PHP_LIB} ${NXT_PHP_LDFLAGS}"
 nxt_feature_test="
     #include <php.h>
 
-    int main() {
+    int main(void) {
         printf(\"%s\", PHP_VERSION);
         return 0;
     }"
@@ -148,7 +148,7 @@ nxt_feature_test="
     #include <php.h>
     #include <php_main.h>
 
-    int main() {
+    int main(void) {
     #if (PHP_VERSION_ID < 80200)
         php_module_startup(NULL, NULL, 0);
     #else
@@ -176,7 +176,7 @@ nxt_feature_test="
     #include <php.h>
     #include <php_main.h>
 
-    int main() {
+    int main(void) {
         #ifndef ZTS
         #error ZTS is not defined.
         #endif
@@ -197,7 +197,7 @@ nxt_feature_test="
     #include <php.h>
     #include <php_main.h>
 
-    int main() {
+    int main(void) {
         zend_signal_startup();
         return 0;
     }"
diff --git a/auto/modules/python b/auto/modules/python
index 9be6b370..480ae1da 100644
--- a/auto/modules/python
+++ b/auto/modules/python
@@ -86,7 +86,7 @@ if /bin/sh -c "$NXT_PYTHON_CONFIG --prefix" >> $NXT_AUTOCONF_ERR 2>&1; then
     nxt_feature_test="
         #include <Python.h>
 
-        int main() {
+        int main(void) {
             Py_Initialize();
             return 0;
         }"
@@ -114,7 +114,7 @@ nxt_feature_test="
     #include <Python.h>
     #include <stdio.h>
 
-    int main() {
+    int main(void) {
         printf(\"%s\", PY_VERSION);
         return 0;
     }"
diff --git a/auto/modules/ruby b/auto/modules/ruby
index dbedfd72..7c2f0102 100644
--- a/auto/modules/ruby
+++ b/auto/modules/ruby
@@ -106,7 +106,7 @@ if /bin/sh -c "$NXT_RUBY -v" >> $NXT_AUTOCONF_ERR 2>&1; then
     nxt_feature_test="
         #include <ruby.h>
 
-        int main() {
+        int main(void) {
             static const char *argv[3] = {
                 \"NGINX_Unit\", \"-rrbconfig\",
                 \"-eprint RbConfig::CONFIG['libdir']\"
@@ -130,7 +130,7 @@ if /bin/sh -c "$NXT_RUBY -v" >> $NXT_AUTOCONF_ERR 2>&1; then
         nxt_feature_test="
             #include <ruby.h>
 
-            int main() {
+            int main(void) {
                 ruby_init();
                 return ruby_cleanup(0);
             }"
@@ -159,7 +159,7 @@ nxt_feature_test="
     #include <ruby.h>
     #include <ruby/version.h>
 
-    int main() {
+    int main(void) {
         printf(\"%s\", ruby_version);
         return 0;
     }"