Godot: Match don't match

[Ducote]

Found nothing like my issue with : _is:issue "match" in:title label:bug state:open_ searching's filter.

Godot version:
Godot Engine v3.2.3.stable.official

OS/device including version:
Ubuntu 20.04
GPU : Nvidia GeForce GTX 970
GPU driver : nvidia driver 450 (libre)
Proc : AMD® Ryzen 9 3900x

Issue description:
Match is supposed to match with the first option... but don't.

Steps to reproduce:
Don't know too much.
Made a variable match with a enum's const.

Minimal reproduction project:
issue_minimal_project.zip

[Calinou]

I can reproduce this on Godot 3.2.3.

That said, the first time I launched the project, I had a different output when clicking the Artistes/Albums button (it toggled between both states).

It works if you add an int type hint to your var declaration:

var searching_mode: int = searching_by.ARTIST

The variable's type can't be inferred for some reason…

[Ducote]

I have the same bug at different location on my script, and it's the same. Thanks for your tips, it works !

What's crazy is that there is a part of my code that worked perfectly fine... Then just broke...

[ShalokShalom]

@karroffel implemented this, so he might be able to help. 🙂

[Calinou]

@ShalokShalom karroffel no longer contributes to Godot core, so I'm afraid he can't help much here.

[strank]

I just tested this on the current master and could not reproduce it. So at least it seems to have been fixed during the GDScript rewrite for 4.0.

[Ducote]

That's good to hear ! Just have to wait for 4.0..... JUST ! ^^

[ThakeeNathees]

JSON parse 0 as 0.0 float and you can't match float 0.0 with int 0 (not sure if it's a bug CC @vnen ) but the bug here is if a float value is a whole number it just prints the integer and ignore the decimal point which is harder for someone to debug.

var value = JSON.parse('0').result ## <-- a float value not integer

func _ready():
    print(value) ## <-- prints 0 not 0.0
    match value:
        0:
            print('0')
        1:
            print('1')
        0.0:
            print('0.0') ## <-- matches here
        _:
            print('default')

[Calinou]

@ThakeeNathees GDScript is a strongly-typed language, so 0 not being equal to 0.0 is a design decision, not a bug.

[Ducote]

Then, why do the if condition work, but match doesn't ?

[vnen]

== works on int and float arguments mostly for convenience. But match is type-strict all the time, since some comparisons would be invalid (if you try to use == with incompatible types you get an error).

So this isn't really a bug, you should cast for the type you expect it to be.

Now I wonder if I broke something on 4.0 or if the test was made with something different, because it should still only match if the type is the same.

[strank]

@vnen my testing mentioned above didn't go through the json parser, my bad. it seems that it's still type-strict in 4.0

[strank]

BTW, I think that matching a pattern with a literal, variable or constant should use the same mechanism and provide exactly the same convenience that the equality test == in that language provides. The reason: to avoid exactly the misunderstanding that led to this issue report.
It is also in line with other languages that support some duck-typing, AFAIK. E.g. case in Ruby (I think) and the pattern matching statement proposed for python https://www.python.org/dev/peps/pep-0622/#patterns

But I guess, this change would have to go into a new proposal.