option sumtype is checking breaks

[felipensp]

V version: V 0.4.9 d680c42, press to see full `v doctor` output

V full version	V 0.4.9 ac71f9e.d680c42
OS	linux, Ubuntu 24.04.1 LTS (WSL 2)
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i5-8365U CPU @ 1.60GHz
Memory	5.54GB/7.67GB
V executable	/home/felipe/v/v
V last modified time	2025-01-16 11:36:32
V home dir	OK, value: /home/felipe/v
VMODULES	OK, value: /home/felipe/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/felipe/v
Git version	git version 2.43.0
V git status	weekly.2025.1-62-gd49b8f9f (2 commit(s) behind V master)
.git/config present	true
cc version	cc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
gcc version	gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0
clang version	Ubuntu clang version 18.1.3 (1ubuntu1)
tcc version	tcc version 0.9.28rc 2024-07-31 HEAD@1cee0908 (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 0134e9b9
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.39-0ubuntu8.3) 2.39

What did you do?
./v -g -o vdbg cmd/v && ./vdbg bug.v && /home/felipe/v/bug

type Foo = int | string
struct Struct {
    a ?Foo
}

fn r(a string){}

fn t(s ?Foo) {
    mut t := Struct{a: s}
    if t.a is string {
        r(t.a)
    }
}
    
fn main() {
    s := ?Foo('hello')
    t(s)
}

What did you see?

================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/bug.01JHQFSW2KWAQ1HHR895159XBV.tmp.c:5641: error: field not found: _typ
=================================================================
(You can pass `-cg`, or `-show-c-output` as well, to print all the C error messages).
builder error: 
==================
C error found. It should never happen, when compiling pure V code.
This is a V compiler bug, please report it using `v bug file.v`,
or goto https://github.com/vlang/v/issues/new/choose .
You can also use #help on Discord: https://discord.gg/vlang .

What did you expect to see?

no crash

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[huly-for-github]

Connected to Huly®: V_0.6-21916

[spytheman]

I think that it should be a checker error, since if t.a is string { , when the a field is declared as ?Foo, means that t.a should be unwrapped first.

[spytheman]

I know that it makes the usage a bit clumsier, but on the other hand, the language rules are easier to apply for both the compiler and the programmer, i.e. option values have to always be unwrapped, before doing stuff on the value, when it is != none .

[spytheman]

This for example should compile/run cleanly (it currently cgen errors, but for another reason):

type Foo = int | string
struct Struct {
    a ?Foo
}

fn r(a string){}

fn t(s ?Foo) {
	mut t := Struct{a: s}
	if t.a != none {
		if t.a is string {
		        r(t.a)
		}
	}
}
    
fn main() {
    s := ?Foo('hello')
    t(s)
}