Debug out-of-range make_fixnum args

With --enable-checking, make_fixnum (N) now checks that N is
in fixnum range.  Suggested by Pip Cet in:
https://lists.gnu.org/r/emacs-devel/2019-07/msg00548.html
A new function make_ufixnum (N) is for the rare cases where N
is intended to be unsigned and is in the range 0..INTMASK.
* configure.ac (AC_C_TYPEOF): Add.
(HAVE_STATEMENT_EXPRESSIONS): Resurrect this macro.
* src/fns.c (Frandom, hashfn_eq, hashfn_equal, hashfn_user_defined):
* src/profiler.c (hashfn_profiler):
Use make_ufixnum rather than make_fixum, since the argument is
an unsigned integer in the range 0..INTMASK rather than a signed
integer in the range MOST_NEGATIVE_FIXNUM..MOST_POSITIVE_FIXNUM.
Typically this is for hashes.
* src/lisp.h (lisp_h_make_fixnum_wrap) [USE_LSB_TAG]:
Rename from lisp_h_make_fixnum.
(lisp_h_make_fixnum): Redefine in terms of lisp_h_make_fixnum_wrap.
Check for fixnum overflow on compilers like GCC that
have statement expressions and typeof.
(FIXNUM_OVERFLOW_P): Move up.
(make_fixnum): Check for fixnum overflow.
(make_ufixnum): New function, which checks that the arg
fits into 0..INTMASK range.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/fns.c b/src/fns.c
index acc6d46db85..920addeaf13 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -87,7 +87,7 @@ See Info node `(elisp)Random Numbers' for more details.  */)
           return make_fixnum (remainder);
         val = get_random ();
       }
-  return make_fixnum (val);
+  return make_ufixnum (val);
 }
 
 /* Random data-structure functions.  */
@@ -3994,7 +3994,7 @@ cmpfn_user_defined (Lisp_Object key1, Lisp_Object key2,
 static Lisp_Object
 hashfn_eq (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
-  return make_fixnum (XHASH (key) ^ XTYPE (key));
+  return make_ufixnum (XHASH (key) ^ XTYPE (key));
 }
 
 /* Ignore HT and return a hash code for KEY which uses 'equal' to compare keys.
@@ -4003,7 +4003,7 @@ hashfn_eq (Lisp_Object key, struct Lisp_Hash_Table *h)
 Lisp_Object
 hashfn_equal (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
-  return make_fixnum (sxhash (key, 0));
+  return make_ufixnum (sxhash (key, 0));
 }
 
 /* Ignore HT and return a hash code for KEY which uses 'eql' to compare keys.
@@ -4023,7 +4023,7 @@ hashfn_user_defined (Lisp_Object key, struct Lisp_Hash_Table *h)
 {
   Lisp_Object args[] = { h->test.user_hash_function, key };
   Lisp_Object hash = hash_table_user_defined_call (ARRAYELTS (args), args, h);
-  return FIXNUMP (hash) ? hash : make_fixnum (sxhash (hash, 0));
+  return FIXNUMP (hash) ? hash : make_ufixnum (sxhash (hash, 0));
 }
 
 struct hash_table_test const