bpo-42598: Fix implicit function declarations in configure (GH-23690)

jmroot · web-flow · commit 674fa0a74015 · 2020-12-13T15:56:34.000-05:00
This is invalid in C99 and later and is an error with some compilers
(e.g. clang in Xcode 12), and can thus cause configure checks to
produce incorrect results.
diff --git a/Misc/NEWS.d/next/Build/2020-12-13-14-43-10.bpo-42598.7ipr5H.rst b/Misc/NEWS.d/next/Build/2020-12-13-14-43-10.bpo-42598.7ipr5H.rst
@@ -0,0 +1,2 @@
+Fix implicit function declarations in configure which could have resulted in
+incorrect configuration checks.  Patch contributed by Joshua Root.
diff --git a/configure b/configure
@@ -11108,10 +11108,10 @@ else
       main() {
         pthread_attr_t attr;
         pthread_t id;
-        if (pthread_attr_init(&attr)) exit(-1);
-        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) exit(-1);
-        if (pthread_create(&id, &attr, foo, NULL)) exit(-1);
-        exit(0);
+        if (pthread_attr_init(&attr)) return (-1);
+        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) return (-1);
+        if (pthread_create(&id, &attr, foo, NULL)) return (-1);
+        return (0);
       }
 _ACEOF
 if ac_fn_c_try_run "$LINENO"; then :
@@ -15130,7 +15130,7 @@ else
   int main()
   {
 	/* Success: exit code 0 */
-        exit((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
+        return ((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
   }
 
 _ACEOF
@@ -15511,7 +15511,7 @@ else
 
 int main()
 {
-	exit(((-1)>>3 == -1) ? 0 : 1);
+	return (((-1)>>3 == -1) ? 0 : 1);
 }
 
 _ACEOF
@@ -15981,6 +15981,7 @@ else
 /* end confdefs.h.  */
 
 #include <poll.h>
+#include <unistd.h>
 
 int main()
 {
diff --git a/configure.ac b/configure.ac
@@ -3311,10 +3311,10 @@ if test "$posix_threads" = "yes"; then
       main() {
         pthread_attr_t attr;
         pthread_t id;
-        if (pthread_attr_init(&attr)) exit(-1);
-        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) exit(-1);
-        if (pthread_create(&id, &attr, foo, NULL)) exit(-1);
-        exit(0);
+        if (pthread_attr_init(&attr)) return (-1);
+        if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) return (-1);
+        if (pthread_create(&id, &attr, foo, NULL)) return (-1);
+        return (0);
       }]])],
       [ac_cv_pthread_system_supported=yes],
       [ac_cv_pthread_system_supported=no],
@@ -4728,7 +4728,7 @@ then
   int main()
   {
 	/* Success: exit code 0 */
-        exit((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
+        return ((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);
   }
   ]])],
   [ac_cv_wchar_t_signed=yes],
@@ -4850,7 +4850,7 @@ AC_CACHE_VAL(ac_cv_rshift_extends_sign, [
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 int main()
 {
-	exit(((-1)>>3 == -1) ? 0 : 1);
+	return (((-1)>>3 == -1) ? 0 : 1);
 }
 ]])],
 [ac_cv_rshift_extends_sign=yes],
@@ -4997,6 +4997,7 @@ AC_MSG_CHECKING(for broken poll())
 AC_CACHE_VAL(ac_cv_broken_poll,
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <poll.h>
+#include <unistd.h>
 
 int main()
 {

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Fix implicit function declarations in configure which could have resulted in`
	`2`	`+incorrect configuration checks. Patch contributed by Joshua Root.`
Original file line number	Diff line number	Diff line change
`@@ -11108,10 +11108,10 @@ else`
`11108`	`11108`	`main() {`
`11109`	`11109`	`pthread_attr_t attr;`
`11110`	`11110`	`pthread_t id;`
`11111`		`- if (pthread_attr_init(&attr)) exit(-1);`
`11112`		`- if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) exit(-1);`
`11113`		`- if (pthread_create(&id, &attr, foo, NULL)) exit(-1);`
`11114`		`- exit(0);`
	`11111`	`+ if (pthread_attr_init(&attr)) return (-1);`
	`11112`	`+ if (pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM)) return (-1);`
	`11113`	`+ if (pthread_create(&id, &attr, foo, NULL)) return (-1);`
	`11114`	`+ return (0);`
`11115`	`11115`	`}`
`11116`	`11116`	`_ACEOF`
`11117`	`11117`	`if ac_fn_c_try_run "$LINENO"; then :`
`@@ -15130,7 +15130,7 @@ else`
`15130`	`15130`	`int main()`
`15131`	`15131`	`{`
`15132`	`15132`	`/* Success: exit code 0 */`
`15133`		`- exit((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);`
	`15133`	`+ return ((((wchar_t) -1) < ((wchar_t) 0)) ? 0 : 1);`
`15134`	`15134`	`}`
`15135`	`15135`
`15136`	`15136`	`_ACEOF`
`@@ -15511,7 +15511,7 @@ else`
`15511`	`15511`
`15512`	`15512`	`int main()`
`15513`	`15513`	`{`
`15514`		`- exit(((-1)>>3 == -1) ? 0 : 1);`
	`15514`	`+ return (((-1)>>3 == -1) ? 0 : 1);`
`15515`	`15515`	`}`
`15516`	`15516`
`15517`	`15517`	`_ACEOF`
`@@ -15981,6 +15981,7 @@ else`
`15981`	`15981`	`/* end confdefs.h. */`
`15982`	`15982`
`15983`	`15983`	`#include <poll.h>`
	`15984`	`+#include <unistd.h>`
`15984`	`15985`
`15985`	`15986`	`int main()`
`15986`	`15987`	`{`