* fns.c (next_almost_prime): Don't return a multiple of 3 or 5.

The previous code was bogus.  For example, next_almost_prime (32)
returned 39, which is undesirable as it is a multiple of 3; and
next_almost_prime (24) returned 25, which is a multiple of 5 so
why was the code bothering to check for multiples of 7?

2 files changed, 9 insertions, 7 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 54fe58d1118..7bd1d47b328 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,11 @@
 2011-06-14  Paul Eggert  <eggert@cs.ucla.edu>
 
+        * fns.c (next_almost_prime): Don't return a multiple of 3 or 5.
+        The previous code was bogus.  For example, next_almost_prime (32)
+        returned 39, which is undesirable as it is a multiple of 3; and
+        next_almost_prime (24) returned 25, which is a multiple of 5 so
+        why was the code bothering to check for multiples of 7?
+
         * bytecode.c (exec_byte_code): Use ptrdiff_t, not int, for vector length.
 
         * eval.c, doprnt.c (SIZE_MAX): Remove; inttypes.h defines this now.
diff --git a/src/fns.c b/src/fns.c
index 0e98a8d3425..333a75ac2b2 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -3379,13 +3379,9 @@ check_hash_table (Lisp_Object obj)
 EMACS_INT
 next_almost_prime (EMACS_INT n)
 {
-  if (n % 2 == 0)
-    n += 1;
-  if (n % 3 == 0)
-    n += 2;
-  if (n % 7 == 0)
-    n += 4;
-  return n;
+  for (n |= 1; ; n += 2)
+    if (n % 3 != 0 && n % 5 != 0 && n % 7 != 0)
+      return n;
 }