support: Expose TEST_VERIFY_EXIT behavior to GCC optimizers

Previously, the implementation would conditionally exit based on the
status argument, which GCC did not know about.  This leads to
false uninitialized variable warnings when data is accessed after a
TEST_VERIFY_EXIT failure (from code which would never execute).

2017-06-07  Florian Weimer  <fweimer@redhat.com>

	Expose TEST_VERIFY_EXIT process termination to GCC optimizers.
	* support/support_test_verify_impl.c
	(support_test_verify_exit_impl): Split from
	support_test_verify_impl.
	* support/check.h (TEST_VERIFY): Drop status argument from
	support_test_verify_impl call.
	(TEST_VERIFY_EXIT): Call support_test_verify_exit_impl.
	(support_test_verify_impl): Remove status argument.
	(support_test_verify_exit_impl): Declare.

diff --git a/support/check.h b/support/check.h
index 1d244a3..bdcd129 100644
--- a/support/check.h
+++ b/support/check.h
@@ -51,7 +51,7 @@ __BEGIN_DECLS
     if (expr)                                                   \
       ;                                                         \
     else                                                        \
-      support_test_verify_impl (-1, __FILE__, __LINE__, #expr); \
+      support_test_verify_impl (__FILE__, __LINE__, #expr);     \
   })
 
 /* Record a test failure and exit if EXPR evaluates to false.  */
@@ -60,7 +60,8 @@ __BEGIN_DECLS
     if (expr)                                                   \
       ;                                                         \
     else                                                        \
-      support_test_verify_impl (1, __FILE__, __LINE__, #expr);  \
+      support_test_verify_exit_impl                             \
+        (1, __FILE__, __LINE__, #expr);                         \
   })
 
 int support_print_failure_impl (const char *file, int line,
@@ -70,8 +71,11 @@ void support_exit_failure_impl (int exit_status,
                                 const char *file, int line,
                                 const char *format, ...)
   __attribute__ ((noreturn, nonnull (2), format (printf, 4, 5)));
-void support_test_verify_impl (int status, const char *file, int line,
+void support_test_verify_impl (const char *file, int line,
                                const char *expr);
+void support_test_verify_exit_impl (int status, const char *file, int line,
+                                    const char *expr)
+  __attribute__ ((noreturn));
 
 /* Record a test failure.  This function returns and does not
    terminate the process.  The failure counter is stored in a shared
diff --git a/support/support_test_verify_impl.c b/support/support_test_verify_impl.c
index 5bae38f..55ab211 100644
--- a/support/support_test_verify_impl.c
+++ b/support/support_test_verify_impl.c
@@ -22,12 +22,16 @@
 #include <stdlib.h>
 
 void
-support_test_verify_impl (int status, const char *file, int line,
-                          const char *expr)
+support_test_verify_impl (const char *file, int line, const char *expr)
 {
   support_record_failure ();
   printf ("error: %s:%d: not true: %s\n", file, line, expr);
-  if (status >= 0)
-    exit (status);
+}
 
+void
+support_test_verify_exit_impl (int status, const char *file, int line,
+                               const char *expr)
+{
+  support_test_verify_impl (file, line, expr);
+  exit (status);
 }