[gjs] arg: Avoid taking abs() of -2^63

[Philip Chimento <pchimento src gnome org>]

commit 9a3e33990996d2a276f6a3930983ba6a44cdd62d
Author: Philip Chimento <philip endlessm com>
Date:   Wed Aug 30 13:36:51 2017 -0700

    arg: Avoid taking abs() of -2^63
    
    It's undefined behaviour to call abs() on (int64_t)(-2^63) because 2^63
    can't be stored in an int64_t. Add a special case for this value.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786995

 gi/arg.cpp |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gi/arg.cpp b/gi/arg.cpp
index d0647fe..34be3a4 100644
--- a/gi/arg.cpp
+++ b/gi/arg.cpp
@@ -2623,7 +2623,8 @@ gjs_value_from_g_argument (JSContext             *context,
         break;
 
     case GI_TYPE_TAG_INT64:
-        if (std::abs(arg->v_int64) > MAX_SAFE_INT64)
+        if (arg->v_int64 == G_MININT64 ||
+            std::abs(arg->v_int64) > MAX_SAFE_INT64)
             g_warning("Value %" G_GINT64_FORMAT " cannot be safely stored in "
                       "a JS Number and may be rounded", arg->v_int64);
         value_p.setNumber(static_cast<double>(arg->v_int64));