From: Taylor R Campbell <campbell@mumble.net>
Date: Fri, 26 Oct 2018 16:15:28 +0000 (+0000)
Subject: clock() returns (clock_t)-1 on error, not necessarily negative.
X-Git-Tag: mit-scheme-pucked-10.1.2~16^2~158
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=b07626c9c53f7ea6a33205987e944606df7b9c8c;p=mit-scheme.git

clock() returns (clock_t)-1 on error, not necessarily negative.

If clock_t is unsigned, n < 0 is always false.  Compare for equality
with (clock_t)-1.
---

diff --git a/src/microcode/prosenv.c b/src/microcode/prosenv.c
index f0d2ac04f..52cf4bb82 100644
--- a/src/microcode/prosenv.c
+++ b/src/microcode/prosenv.c
@@ -141,7 +141,7 @@ DEFINE_PRIMITIVE ("CURRENT-JIFFY", Prim_current_jiffy, 0, 0, 0)
 {
   PRIMITIVE_HEADER (0);
   clock_t n = (OS_current_jiffy ());
-  PRIMITIVE_RETURN ((n < 0) ? SHARP_F : (intmax_to_integer (n)));
+  PRIMITIVE_RETURN ((n == (clock_t)-1) ? SHARP_F : (intmax_to_integer (n)));
 }
 
 DEFINE_PRIMITIVE ("JIFFIES-PER-SECOND", Prim_jiffies_per_second, 0, 0, 0)