Code location from previous command failure is sometimes retained

[quexxon]

In this example, calling p initially shows the expected code location in the echo error, but after calling echo erroneously at the top-level, the code location from the last failed top-level execution is displayed thereafter when calling p.

ysh-0.24.0$ proc p (...args) {
>   echo $args # introducing a bug so this fails
> }

ysh-0.24.0$ p 1 2 3
    echo $args # introducing a bug so this fails
    ^~~~
[ interactive ]:2: fatal: Word eval got a List, which can't be stringified (OILS-ERR-203)

ysh-0.24.0$ echo $[{}]
  echo $[{}]
       ^~
[ interactive ]:5: fatal: Expr sub expected one of (Null Bool Int Float Str Eggex), got Dict

ysh-0.24.0$ p 1 2 3
  echo $[{}]
       ^~
[ interactive ]:5: fatal: Word eval got a List, which can't be stringified (OILS-ERR-203)

[andychu]

Ah OK, I think this is because we have a loc.Missing combined a failure to set the "fallback" location

I will look at this, thank you!

[andychu]

OK I repro'd this ... looking into it

[andychu]

OK I narrowed the bug down to this code:

https://github.com/oils-for-unix/oils/blob/master/core/state.py#L1370

• in theory, we want locations attached to every message

  • in practice, sometimes we have loc.Missing, and "fall back" to the "last known" location

• there is a fallback location for expressions, and a fallback location for statements

• the expression location is considered more "specific", so it's preferred

But that's wrong here

Because the one for statements is more recent

---

So there are probably 2 fixes

• remove the loc.Missing, supply a real location with the error
• fix the logic about expressions vs. statements, not sure what it should be

---

this is a very good bug, thanks for the report!

[andychu]

I just fixed this, and improved the error location too.

    echo $args
         ^~~~~
[ -c flag ]:3: fatal: Word eval got a List, which can't be stringified (OILS-ERR-203)
  echo $[{}]
       ^~
[ -c flag ]:8: fatal: Expr sub expected one of (Null Bool Int Float Str Eggex), got Dict
    echo $args
         ^~~~~
[ -c flag ]:3: fatal: Word eval got a List, which can't be stringified (OILS-ERR-203)

Thanks for the report!