gh-123917: Fix crypt check in configure

vstinner · madscientist · vstinner · commit 7719552468fb · 2024-09-11T16:09:20.000+02:00
Use the volatile keyword when checking crypt_r() or crypt() function
in the configure script. Without volatile, the assignment can be
removed by an optimization.

Co-Authored-By: Paul Smith &lt;paul@mad-scientist.net&gt;
diff --git a/Misc/NEWS.d/next/Build/2024-09-11-16-06-42.gh-issue-123917.JuZl0r.rst b/Misc/NEWS.d/next/Build/2024-09-11-16-06-42.gh-issue-123917.JuZl0r.rst
@@ -0,0 +1,3 @@
+Fix the check for the ``crypt()`` function in the configure script: use the
+``volatile`` keyword to prevent the compiler to remove the check. Patch by
+Paul Smith and Victor Stinner.
diff --git a/configure b/configure
diff --git a/configure.ac b/configure.ac
@@ -5239,9 +5239,9 @@ WITH_SAVE_ENV([
         #include <unistd.h>
       ], [
         #ifdef HAVE_CRYPT_R
-          void *x = crypt_r;
+          volatile void *x = crypt_r;
         #else
-          void *x = crypt;
+          volatile void *x = crypt;
         #endif
       ])
     ], [ac_cv_crypt_crypt=yes], [ac_cv_crypt_crypt=no])

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	+Fix the check for the ``crypt()`` function in the configure script: use the
	`2`	+``volatile`` keyword to prevent the compiler to remove the check. Patch by
	`3`	`+Paul Smith and Victor Stinner.`