C error on casting optional struct field

[gechandesu]

V doctor:

V full version: V 0.4.8 5ec9bb5.1345eac
OS: linux, Linux version 6.6.8-arch1-1 (linux@archlinux) (gcc (GCC) 13.2.1 20230801, GNU ld (GNU Binutils) 2.41.0) #1 SMP PREEMPT_DYNAMIC Thu, 21 Dec 2023 19:01:01 +0000
Processor: 16 cpus, 64bit, little endian, 12th Gen Intel(R) Core(TM) i5-1240P

getwd: /home/ge/Code/v/netaddr/issues
vexe: /home/ge/.vlang/v
vexe mtime: 2024-11-24 11:11:18

vroot: OK, value: /home/ge/.vlang
VMODULES: OK, value: /home/ge/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.46.1
Git vroot status: weekly.2024.47-25-g1345eac5
.git/config present: true

CC version: cc (GCC) 14.2.1 20240910
emcc version: N/A
thirdparty/tcc status: thirdparty-linux-amd64 0134e9b9

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

module main

struct Foo {
	foo string
	bar ?string
}

fn (f Foo) str() string {
	mut ret := f.foo
	bar_value := f.bar as string
	if bar_value == '' {
		return ret
	}
	return ret + '%' + bar_value
}

fn main() {
	ff := Foo{
		foo: 'Fooooo'
	}
	println(ff)
}

What did you expect to see?

'Fooooo' printed

What did you see instead?

================== C compilation error (from tcc): ==============
cc: /tmp/v_1000/casting_optional_field_struct_method.01JDEXY0DVN2RRQBB8CKSSYVTN.tmp.c:13719: error: '{' expected (got ";")
=================================================================
(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 .

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_{Huly®: V_0.6-21401}

[Delta456]

The below code is a workaround when #22953 gets merged. I will work on this after.

module main

struct Foo {
	foo string
	bar ?string
}

fn (f Foo) str() string {
	mut ret := f.foo
	v := f.bar
	bar_value := v as string
	if bar_value == '' {
		return ret
	}
	return ret + '%' + bar_value
}

fn main() {
	ff := Foo{
		foo: 'Fooooo'
	}
	println(ff)
}