support: Increase usability of TEST_COMPARE

The previous implementation of the TEST_COMPARE macro would fail
to compile code like this:

  int ret = res_send (query, sizeof (query), buf, sizeof (buf));
  TEST_COMPARE (ret,
                sizeof (query)
                + 2             /* Compression reference.  */
                + 2 + 2 + 4 + 2 /* Type, class, TTL, RDATA length.  */
                + 1             /* Pascal-style string length.  */
                + strlen (expected_name));

This resulted in a failed static assertion, "integer conversions
may alter sign of operands".  A user of the TEST_COMPARE would have
to add a cast to fix this.

This patch reverts to the original proposed solution of a run-time
check, making TEST_COMPARE usable for comparisons of numbers with
types with different signedness in more contexts.

1 files changed, 12 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 8824881131..a7799fcdd6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2018-01-08  Florian Weimer  <fweimer@redhat.com>
+
+	* support/check.h (TEST_COMPARE): Allow sign mismatch at compile
+	time.  Pass positive flag instead of negative flag to
+	support_test_compare_failure.
+	(support_test_compare_failure): Change negative parameter to
+	positive.
+	* support/support_test_compare_failure.c (report)
+	(support_test_compare_failure): Likewise.
+	* support/tst-test_compare.c (return_ssize_t, return_int): New.
+	(do_test): Check int/size_t, ssize_t/size_t comparisons.
+
 2018-01-08  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	[BZ #22637]