command line variable assignments

[Tom Lord]

Versions 3.0.3 and 3.0.6 both seem to think that an "=" in a 
command line argument indicates a variable assignment rather
than a filename.  As I read the spec, this is so only if the 
text to the left of the "=" begins with an underscore or letter and
contains only characters which are valid in identifiers -- otherwise
the argument must be treated as a filename.

In other words:

        ./gawk [....] /foo/bar/=dir/etc

is not a syntax error or bad variable assignment -- it tells awk to
read its input from the named file.

The problem seems to be caused by calling `main.c(arg_assign)' in
`io.c(nextfile)'.  `arg_assign' applies a check suitable for `-v'
option arguments, but not for ordinary arguments.

-t