A preprocessing directive of the form
(that does not match the previous form) is permitted
. The preprocessing tokens after
include
in the directive are processed just as in normal text
(i.e., each identifier currently defined as a macro name is replaced by its
replacement list of preprocessing tokens)
. Then, an attempt is made to form a
preprocessing token (
[lex.header]) from the whitespace and the characters
of the spellings of the resulting sequence of preprocessing tokens;
the treatment of whitespace
is
implementation-defined
. If the attempt succeeds, the directive with the so-formed
is processed as specified for the previous form
. Otherwise, the behavior is undefined
.