cgen error for Sumtype( f() or { variant_value } )

[spytheman]

V doctor:

V full version: V 0.4.8 a132d97.ec1f95a
OS: linux, Ubuntu 20.04.6 LTS
Processor: 2 cpus, 64bit, little endian, Intel(R) Core(TM) i3-3225 CPU @ 3.30GHz

getwd: /home/delian/code/v
vexe: /home/delian/code/v/v
vexe mtime: 2024-11-11 17:27:28

vroot: OK, value: /home/delian/code/v
VMODULES: OK, value: /home/delian/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.46.0
Git vroot status: weekly.2024.46-1-gec1f95ac-dirty
.git/config present: true

CC version: cc (Ubuntu 10.5.0-1ubuntu1~20.04) 10.5.0
emcc version: N/A
thirdparty/tcc status: thirdparty-linux-amd64 0134e9b9

What did you do?
./v -g -o vdbg cmd/v && ./vdbg oo.v

type Aa = string | int

fn f() !string {
	return ''
}

y := Aa(f() or { 2 })
println(y)

What did you expect to see?

a compiled program, or a checker error

What did you see instead?

================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/oo.01JCE5SGAZ2BEB2ATKXPA41MXY.tmp.c:13771: error: cannot convert 'int' to 'struct string'
=================================================================
(You can pass `-cg`, or `-show-c-output` as well, to print all the C error messages).

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_{Huly®: V_0.6-21280}

[spytheman]

Note, an alternative that compiles is:

type Aa = string | int
fn f() !string { return '' }
y := if x := f() { Aa(x) } else { 2 }
println(y)

[spytheman]

The checker has to produce an error for y := Aa(f() or { 2 }), since the 2 in the or branch is not a string, i.e. the expected type there should come from the return type of f() which is !string -> only a string value is valid as a default value in the or branch.

[spytheman]

i.e. the goal is that the type of the whole expression f() or { expr } should be string as well, and then the cast to a sumtype value can work properly.

[felipensp]

And along this points it should allow foo() or {} and foo() or { foo = 1; }, that is... is_return_used may help us now :-)