document #15618

[ringabout]

No description provided.

[timotheecour]

Can we fix it instead?

[ringabout]

I think we should make this work to fix this issue.

var x = 4
doAssert 4.0 == x

[timotheecour]

I think we should make this work to fix this issue.

no, this can't work.
But check 4.0 == 2 + 2 should work

[ringabout]

check 4.0 == 2 + 2 is converted to this for supporting checkpoints. It seems hard to fix.

var x = 2 + 2    # maybe have side effects
doAsssert 4.0 == x
checkpointes(... & $x)

And

func double*(n: float): float = n * 2
doAssert(double(-2) == -4)
test "double -2": check(double(-2) == -4)

is converted to:

func double*(n: float): float = n * 2

var x = double(-2) # maybe have side effects
doAssert(x == -4)
checkpointes(... & $x)

[timotheecour]

It seems hard to fix.

check lhs == rhs
=>
var rhs2: type(lhs) = rhs

note that in future work {.evalonce.} might be worth considering eg: let rhs2 {.evalonce.}: type(lhs) = expr refs #13750

[ringabout]

Thanks for hints! I will give a try.

But how about this?

import unittest


check 2.0 + 2.0 == 2 + 2  # works with doAssert
check 2 + 2 == 2.0 + 2.0 # works with doAssert

var x: int = 2.0 + 2.0 # This failed.

or lhs and rhs are both functions.

It may not be hard. But I think It is error-prone.

[timotheecour]

nnkIntLit is special, its type is determined from context.

here's a working prototype:

when true:
  import macros
  macro commonType(a, b: typed): untyped =
    if a.kind == nnkIntLit:
      result = quote do:
        type(`b`)
    else:
      result = quote do:
        type(`a`)

  macro check2(cond: untyped): untyped =
    let op=cond[0]
    let a1=cond[1]
    let a2=cond[2]
    let s = cond.repr.newLit
    result = quote do:
      type T = commonType(`a1`, `a2`)
      let lhs: T = `a1`
      let rhs: T = `a2`
      if not(`op`(lhs, rhs)):
        doAssert false, $(lhs, rhs, `s`)
  check2(2+2 == 2.0 + 2.0)
  check2(2.0 + 2.0 == 2+2)
  check2(2+3 == 2.0 + 2.0) # this will show the errmsg