if mut: optional mut after an if check it's not mutable

[esquerbatua]

Describe the bug

Modify an option after checks if it's different of none

Reproduction Steps

fn main() {
	mut option_1 := ?int(10)
	if option_1 != none {
		option_1 = 11
	}

    println('Options: ${option_1}')
}

Expected Behavior

Prints: Options: 11

Current Behavior

.v:21:3: error: `option_1` is immutable, declare it with `mut` to make it mutable
   19 |     mut option_1 := ?int(10)
   20 |     if option_1 != none {
   21 |         option_1 = 10
      |         ~~~~~~~~
   22 |     }
   23 |

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.10 8320da2.f250636

Environment details (OS name and version, etc.)

V full version	V 0.4.10 8320da2.f250636
OS	linux, Ubuntu 24.04.2 LTS
Processor	16 cpus, 64bit, little endian, AMD Ryzen 7 7840HS w/ Radeon 780M Graphics
Memory	47.46GB/86.23GB
V executable	/home/esquerbatua/git/v/v
V last modified time	2025-06-10 17:25:18
V home dir	OK, value: /home/esquerbatua/git/v
VMODULES	OK, value: /home/esquerbatua/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/esquerbatua/git/breakV
Git version	git version 2.43.0
V git status	weekly.2025.16-285-gf2506368
.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	N/A
tcc version	tcc version 0.9.28rc 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.39-0ubuntu8.4) 2.39

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[huly-for-github]

Connected to Huly®: V_0.6-23048

[jorgeluismireles]

With an extra mut works:

fn main() {
	mut option_1 := ?int(10)
	if mut option_1 != none {
		option_1 = 11
	}

    println('Options: ${option_1}')
}

Options: Option(11)

[jorgeluismireles]

This also works, but is unexpected !

fn main() {
	option_1 := ?int(10)
	if mut option_1 != none {
		option_1 = 11
	}

    println('Options: ${option_1}')
}

[felipensp]

This also works, but is unexpected !

fn main() {
option_1 := ?int(10)
if mut option_1 != none {
option_1 = 11
}

println('Options: ${option_1}')

}

I've submitted a PR #24694 to fix it. Thanks.

[felipensp]

With an extra mut works:

fn main() {
mut option_1 := ?int(10)
if mut option_1 != none {
option_1 = 11
}

println('Options: ${option_1}')

}

Options: Option(11)

This is the expected behavior and way to change it. Not a bug.