jarhart/rattler — pull request #9 by wconrad (2014-06-27 11:42:50+00:00)
Title: Warn about textual substitution of labels in normal semantic nodes

This is a warning for something that just bit me:

```
exponent_edit_descriptor <- letter:[ED] width:unsigned_integer
"." fractional_digits:unsigned_integer
exponent_digits:( ~"E" unsigned_integer )?
{
exponent_digits = exponent_digits.first || :default
ExponentEditDescriptor.new(
width,
fractional_digits,
exponent_digits: exponent_digits,
letter: letter
)
}
```

After substitution, the semantic rule became:

```
exponent_edit_descriptor <- letter:[ED] width:unsigned_integer
"." fractional_digits:unsigned_integer
exponent_digits:( ~"E" unsigned_integer )?
{
exponent_digits = exponent_digits.first || :default
ExponentEditDescriptor.new(
width,
fractional_digits,
r0_4: r0_4,
r0_0: r0_0
)
}
```

with the error message "unknown keywords: r0_4, r0_0". Confusion resulted.