Avoid negation of signed integers in C that may hold INT*_MIN.

Reported by minoki.
Recent C compilers 'take advantage' of the undefined behavior.
This completely changes the meaning of expressions like (k == -k).

1 files changed, 1 insertions, 1 deletions

diff --git a/src/lj_obj.h b/src/lj_obj.h
index ea8fe870..ef45ae12 100644
--- a/src/lj_obj.h
+++ b/src/lj_obj.h
@@ -327,7 +327,7 @@ typedef struct GCproto {
 #define PROTO_UV_IMMUTABLE      0x4000  /* Immutable upvalue. */
 
 #define proto_kgc(pt, idx) \
-  check_exp((uintptr_t)(intptr_t)(idx) >= (uintptr_t)-(intptr_t)(pt)->sizekgc, \
+  check_exp((uintptr_t)(intptr_t)(idx) >= ~(uintptr_t)(pt)->sizekgc+1u, \
             gcref(mref((pt)->k, GCRef)[(idx)]))
 #define proto_knumtv(pt, idx) \
   check_exp((uintptr_t)(idx) < (pt)->sizekn, &mref((pt)->k, TValue)[(idx)])