Defined behavior for extraordinary values of _Bool would be preferable, but we can at least document what we have now.


2016-09-19  Florian Weimer  <>

        * doc/implement-c.texi (Integers implementation): _Bool has trap

Index: gcc/doc/implement-c.texi
--- gcc/doc/implement-c.texi	(revision 240228)
+++ gcc/doc/implement-c.texi	(working copy)
@@ -239,9 +239,13 @@
 two's complement, or one's complement, and whether the extraordinary value
 is a trap representation or an ordinary value (C99 and C11}
-GCC supports only two's complement integer types, and all bit patterns
-are ordinary values.
+The standard integer types except @code{_Bool} are represented in two's
+complement, and all bit patterns are ordinary values.
+Ordinary values of @code{_Bool} are stored in memory as bytes with
+values 0 or 1.  Other byte values are trap representations of the
+@code{_Bool} type.
 @cite{The rank of any extended integer type relative to another extended
 integer type with the same precision (C99 and C11}

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