optional val return in map got a wrong value

[kbkpbot]

Describe the bug

See code
may related to issue #26235

Reproduction Steps

o3.v

fn main() {
        mut x := map[string]?string{}
        y := x['123'] or { 'abc' }
        dump(y)
}

Expected Behavior

$ v run o3.v
[o3.v:4] y: 'abc'

Current Behavior

$ v run o3.v
[o3.v:4] y: Option(none)

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.5.0 e2f5d6c.a3fd7f3

Environment details (OS name and version, etc.)

V full version	V 0.5.0 e2f5d6c.a3fd7f3
OS	linux, Ubuntu 24.04.3 LTS
Processor	8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-9700 CPU @ 3.00GHz
Memory	11.96GB/15.51GB
V executable	/media/HD/github/kbkpbot/v/v
V last modified time	2026-01-01 08:03:43
V home dir	OK, value: /media/HD/github/kbkpbot/v
VMODULES	OK, value: /home/mars/.vmodules
VTMP	OK, value: /tmp/v_1000
Current working dir	OK, value: /home/mars/v/bug/none
Git version	git version 2.43.0
V git status	weekly.2025.52-105-ga3fd7f39-dirty
.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 2025-02-13 HEAD@f8bd136d (x86_64 Linux)
tcc git status	thirdparty-linux-amd64 696c1d84
emcc version	N/A
glibc version	ldd (Ubuntu GLIBC 2.39-0ubuntu8.6) 2.39

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[kbkpbot]

I am not sure the result should be

[o3.v:4] y: Option('abc')

or

[o3.v:4] y: 'abc'

here....

[kbkpbot]

And I do think following is valid code, but checker think it is not.

fn main() {
        v := ?string('abc')
        mut x := map[string]?string{}
        y := x['123'] or { v }
        dump(y)
}

o33.v:4:21: error: `or` block must provide a value of type `string`, not `?string`
    2 |     v := ?string('abc')
    3 |     mut x := map[string]?string{}
    4 |     y := x['123'] or { v }
      |                        ^
    5 |     dump(y)
    6 | }

[Delta456]

I am not sure the result should be

[o3.v:4] y: Option('abc')

or

[o3.v:4] y: 'abc'

here....

It should be Option('abc') because the value type is ?string.

[kbkpbot]

I am not sure the result should be

[o3.v:4] y: Option('abc')

or

[o3.v:4] y: 'abc'

here....

It should be Option('abc') because the value type is ?string.

Yes, I think this is a correct answer.
So we need to fix the checker, it seems remove all option and result flags when in a or block.

[felipensp]

I am not sure the result should be

[o3.v:4] y: Option('abc')

or

[o3.v:4] y: 'abc'

here....

It should be Option('abc') because the value type is ?string.

Yes, I think this is a correct answer. So we need to fix the checker, it seems remove all option and result flags when in a or block.

Because in some cases it should acts as unwrapping, like:

	a := ?int(1)
	dump(a or { 2 })

[tankf33der]

@kbkpbot @felipensp

Loss of virginity through Claude Code.
30min of work + 30min testing.
Tested on the whole vlib/

diff --git a/vlib/v/gen/c/index.v b/vlib/v/gen/c/index.v
index d337a060b..1b8692f68 100644
--- a/vlib/v/gen/c/index.v
+++ b/vlib/v/gen/c/index.v
@@ -583,10 +583,14 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 					return
 				}
 			}
+			val_is_opt := val_type.has_flag(.option)
 			opt_val_type := g.styp(val_type.set_flag(.option))
 			g.writeln('${opt_val_type} ${tmp_opt} = {0};')
 			g.writeln('if (${tmp_opt_ptr}) {')
-			if val_sym.kind == .array_fixed {
+			if val_is_opt {
+				// val_type is already an option type; tmp_opt IS the option, assign directly
+				g.writeln('\t${tmp_opt} = *(${val_type_str}*)${tmp_opt_ptr};')
+			} else if val_sym.kind == .array_fixed {
 				g.writeln('\tmemcpy((${val_type_str}*)${tmp_opt}.data, (${val_type_str}*)${tmp_opt_ptr}, sizeof(${val_type_str}));')
 			} else {
 				g.writeln('\t*((${val_type_str}*)&${tmp_opt}.data) = *((${val_type_str}*)${tmp_opt_ptr});')
@@ -597,7 +601,11 @@ fn (mut g Gen) index_of_map(node ast.IndexExpr, sym ast.TypeSymbol) {
 			if !node.is_option {
 				g.or_block(tmp_opt, node.or_expr, val_type)
 			}
-			g.write('\n${cur_line}(*(${val_type_str}*)${tmp_opt}.data)')
+			if val_is_opt {
+				g.write('\n${cur_line}${tmp_opt}')
+			} else {
+				g.write('\n${cur_line}(*(${val_type_str}*)${tmp_opt}.data)')
+			}
 		}
 	}
 }

lambda:~/v$ v run m.v 
[m.v:4] y: Option('abc')
lambda:~/v$