Repeating a field name in a type results in miscompilation

[ColonelPhantom]

Reproducing the behavior

With the code

type Expr
  = (Lit Int)
  | (Plus Expr Expr)

eval (Expr/Lit i) = i
eval (Expr/Plus l r) = (+ (eval l) (eval r))

main = (eval (Expr/Plus (Expr/Lit 80) (Expr/Lit 90)))

running it with at least both run and run-c gives the wrong result of 180, rather than 170.

Without eval, Bend also seems to print something like (+ 90 90) rather than (+ 80 90)

System Settings

• hvm 2.0.19
• bend-lang 0.2.33
• OS: Linux
• CPU: i5-8350U

Additional context

Could this be related to unsafe dup-ing? I thought that that would only affect unrealistic program, not this very simple one.

[LunaAmora]

This is happening because the Plus constructor has both fields with the same name Expr (the names inside constructors are field names, not types), so bend miscompiles it.

As a fix, before the compiler catches this problem and suggest this itself, you can name then (Plus left right), or any other names you would prefer.

[developedby]

At some point in the past the compiler checked for repeated field names, but it seems I accidentally removed it.