Better compiler warning/error messages

[jrenner]

Not to be cliche by comparing to Rust, but in learning some Rust recently I was blown away by how helpful the compiler error messages were. I think Nim could improve a lot in this area, and I might be interested in helping out if the maintainers think it would be a good idea.

Here is one example I ran across recently:

import strformat

let x = "{t}"
let fmt_x = x.fmt

compiler message: Error: & only works with string literals

improvement: might also mention something about "fmt", & made me think of string concat at first suggested new message: Error: strformat module string formatting (fmt(), &) only works with string literals

I'm curious what others think.

[data-man]

https://github.com/nim-lang/Nim/issues?q=is%3Aopen+is%3Aissue+label%3A"Error+messages"

[jrenner]

That search query doesn't seem to have any results for me.

I did however find this:

3914

It looks this is an area that could use some work.

[kaushalmodi]

@jrenner So how did you get around that limitation.. I have really long message formatting, and instead of copy/pasting the message, I wished I could store the string representing that format to a var and do fmt(VAR).

Here's a simple case:

import strformat
let
  a = 100
  msg = "a = {a}"

echo fmt(msg)

But here's that actual msg: "The '{argval}' value for ':{arg}' is invalid. The only valid values are 'yes' and 'no'.".