What to use for finding as many syntax errors as possible.

[Peter J. Holzer]

On 2022-10-10 09:23:27 +1100, Chris Angelico wrote:
> On Mon, 10 Oct 2022 at 06:50, Antoon Pardon <antoon.pardon at vub.be> wrote:
> > I just want a parser that doesn't give up on encoutering the first syntax
> > error. Maybe do some semantic checking like checking the number of parameters.
> 
> That doesn't make sense though.

I think you disagree with most compiler authors here.

> It's one thing to keep going after finding a non-syntactic error, but
> an error of syntax *by definition* makes parsing the rest of the file
> dubious.

Dubious but still useful.

> What would it even *mean* to not give up?

Read the blog post on Lezer for some ideas:
https://marijnhaverbeke.nl/blog/lezer.html

This is in the context of an editor. But the same problem applies to
compilers. It's not very important if a compile run only takes a second
or so but even then it might be helpful to see several error messages
and not only one at a time. It becomes much more important as compile
times get longer (as an extreme[1] example, when I worked on a largeish
cobol program in the 1980s, compiling the thing took about half an hour.
I really wanted to fix *everything* before starting the compiler again.)

Marijn isn't the only person who revisited this problem recently[2].
I've read a few other blog posts and papers on that topic at about the
same time.

        hp

[1] Yes, there are programs where a full compile takes much longer than
    that. But you can usually get away with recompiling only a small
    part, so you don't have to wait that long during normal development.
    That cobol compiler couldn't do that.

[2] "Recently" means "in the last 10 years or so".

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | hjp at hjp.at         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"
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