Inconsistent error message for incompatible return type in nested if / else

[isaacabraham]

This code correctly does not compile. However, the error messages across both branches in the inner if / else are not consistent: -

let x = 1
if x = 1 then true
else
    if x = 2 then "A" // The expression was expected to have type 'bool' but here has type 'string'
    else "B" // All branches of an 'if' expression must have the same return type. This expression was expected to have type 'bool' but here has type 'string'.

I would have expected both errors to be the same, using second version (the F#4.1 improved error message).

cc: @forki

[forki]

This is very hard to do since you don't know how deep this goes.

[forki]

fsi only reports the first one:

[forki]

would this help?

[forki]

WIP: #3150

[isaacabraham]

Would it be possible to use the same error messages in both places? I'm not really sure what "context type requirements" would mean to a newbie either.

[forki]

No we can't use the same error message. It's different reasons. Am 30.05.2017 9:28 vorm. schrieb "Isaac Abraham" <[email protected]>:

…

Would it be possible to use the same error messages in both places? I'm not really sure what "context type requirements" would mean to a newbie either. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#3146 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADgNGr3MbIgO4qZ_C6zV9DN1FdVCKsiks5r-8UzgaJpZM4Non3f> .

[isaacabraham]

What are the different reasons? It's an expression that needs to give consistent results; one half returns bool and the other half returns some non-bool. Yes, it trickles down but why is it any different?

[forki]

Seems I found a way:

[forki]

as you can see in e2b9efd this evaluates the current context and passes the Else info down if we are already in else branch.