The restrictions that ISO C places on the second parameter to the
va_start macro in header 
are different in this document
.The parameter
parmN
is the rightmost parameter in the variable parameter list
of the function definition (the one just before the
...)
.
If the parameter 
parmN is a pack expansion (
[temp.variadic]) or
an entity resulting from a lambda capture (
[expr.prim.lambda]),
the program is ill-formed, no diagnostic required
.If the parameter
parmN
is of a reference type, or of a type that is not compatible with the
type that results when passing an argument for which there is no
parameter, the behavior is undefined
.