catcode problems with `@include`

[Werner LEMBERG]

[texinfo.tex version 2023-08-13.14]


Please consider the attached files.  If I say

```
luatex foo.texinfo
```

the `@tex` environment within this file works just fine, and file
`foo.lua` is correctly loaded.  However, saying

```
luatex bar.texinfo
```

which includes file `bar.itexi`, I get an error:

```
(./bar.itexi[\directlua]:1: ')' expected near '@'.
l.5     dofile(kpse.find_file("bar.lua")) }
```

AFAICS, there is a problem with the handling of underscores in
included files that contain a `@tex` environment, having the wrong
catcode.


    Werner

\input texinfo

@tex
\ifx\luatexversion\thisisundefined
\else
  \directlua{
    dofile(kpse.find_file("foobar.lua")) }
\fi
@end tex

foobar

@bye

local foo = "bar"

\input texinfo
@include bar.itexi

foobar

@bye

@tex
\ifx\luatexversion\thisisundefined
\else
  \directlua{
    dofile(kpse.find_file("bar.lua")) }
\fi
@end tex

local foo = "bar"