Re: Suspicious warning in W64 build

[Paul Eggert <eggert@cs.ucla.edu>]

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Philipp Stephani wrote:
> How about rewriting the function body like this:

Yes, that should work and avoids either UNINIT or some other pacifier. Also, 
while looking at it, I noticed an actual bug in min and max, which is a plus. I 
installed the attached into emacs-26, to fix both problems.

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From 5f28f0db73c03b98b27e04a458ebb209b5d9acde Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 17 Sep 2017 15:25:44 -0700
Subject: [PATCH] Fix bug with min and max and NaNs

* src/data.c (minmax_driver): Fix bug with (min 0 NaN), which
mistakenly yielded 0.  Also, pacify GCC in a better way.
* test/src/data-tests.el (data-tests-min): Test for the bug.
---
 src/data.c             | 12 ++++++------
 test/src/data-tests.el |  6 +++++-
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/data.c b/src/data.c
index 95bf06e..e070be6 100644
--- a/src/data.c
+++ b/src/data.c
@@ -3010,16 +3010,16 @@ static Lisp_Object
 minmax_driver (ptrdiff_t nargs, Lisp_Object *args,
 	       enum Arith_Comparison comparison)
 {
-  eassume (0 < nargs);
-  Lisp_Object accum = args[0];	/* pacify GCC */
-  for (ptrdiff_t argnum = 0; argnum < nargs; argnum++)
+  Lisp_Object accum = args[0];
+  CHECK_NUMBER_OR_FLOAT_COERCE_MARKER (accum);
+  for (ptrdiff_t argnum = 1; argnum < nargs; argnum++)
     {
       Lisp_Object val = args[argnum];
       CHECK_NUMBER_OR_FLOAT_COERCE_MARKER (val);
-      if (argnum == 0 || !NILP (arithcompare (val, accum, comparison)))
+      if (!NILP (arithcompare (val, accum, comparison)))
 	accum = val;
-      else if (FLOATP (accum) && isnan (XFLOAT_DATA (accum)))
-	return accum;
+      else if (FLOATP (val) && isnan (XFLOAT_DATA (val)))
+	return val;
     }
   return accum;
 }
diff --git a/test/src/data-tests.el b/test/src/data-tests.el
index 5dc2634..8de8c14 100644
--- a/test/src/data-tests.el
+++ b/test/src/data-tests.el
@@ -101,7 +101,11 @@
   (should (= 3 (apply #'min '(3 8 3))))
   (should-error (min 9 8 'foo))
   (should-error (min (make-marker)))
-  (should (eql 1 (min (point-min-marker) 1))))
+  (should (eql 1 (min (point-min-marker) 1)))
+  (should (isnan (min 0.0e+NaN)))
+  (should (isnan (min 0.0e+NaN 1 2)))
+  (should (isnan (min 1.0 0.0e+NaN)))
+  (should (isnan (min 1.0 0.0e+NaN 1.1))))
 
 ;; Bool vector tests.  Compactly represent bool vectors as hex
 ;; strings.
-- 
2.7.4