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cgen: fix pointer reference in for-in fixed-array iteration with & [fj4WqyCCw3C5ShR1RfB7MoBPTpkRrBFYP1uT35g3MvT] #28166

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cgen: fix pointer reference in for-in fixed-array iteration with & [fj4WqyCCw3C5ShR1RfB7MoBPTpkRrBFYP1uT35g3MvT] #28166

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1a03f7d
fix: correct pointer reference in for-in fixed-array iteration with &…
waterWang Aug 24, 2026
305e296
test: add regression test for for-in fixed-array ref iteration
waterWang Aug 24, 2026
f020690
test: add expected output for for-in fixed-array ref test
waterWang Aug 24, 2026
db4bf05
test: add C code pattern check for for-in fixed-array ref
waterWang Aug 24, 2026
874a934
test: update C code pattern check for fixed-array ref
waterWang Aug 24, 2026
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2 changes: 1 addition & 1 deletion vlib/v/gen/c/for.v
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Original file line number Diff line number Diff line change
Expand Up @@ -917,7 +917,7 @@ fn (mut g Gen) for_in_stmt(node_ ast.ForInStmt) {
g.write('\t${styp} ${c_name(node.val_var)}')
}
if !is_fixed_array {
addr := if node.val_is_mut { '&' } else { '' }
addr := if node.val_is_mut || node.val_is_ref { '&' } else { '' }

@chatgpt-codex-connector chatgpt-codex-connector Bot Aug 24, 2026

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P1 Badge Preserve pointer elements during reference iteration

When the fixed array's element type is already a pointer, such as mut items := [2]&Item{} followed by for item in &items, for_in_val_type deliberately leaves the loop variable as &Item rather than creating &&Item. This unconditional & now emits an initializer equivalent to Item *item = &items[idx], whose right side is Item **, so previously valid reference iteration over fixed arrays of pointers fails C compilation. Only take the element address when reference iteration actually added a pointer level.

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if cond_type_is_ptr {
g.writeln(' = ${addr}(*${cond_var})[${idx}];')
} else if cond_is_literal {
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1 change: 1 addition & 0 deletions vlib/v/gen/c/testdata/for_in_fixed_array_ref.c.must_have
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@@ -0,0 +1 @@
= &(*
3 changes: 3 additions & 0 deletions vlib/v/gen/c/testdata/for_in_fixed_array_ref.out
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@@ -0,0 +1,3 @@
1
3
5
19 changes: 19 additions & 0 deletions vlib/v/gen/c/testdata/for_in_fixed_array_ref.vv
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@@ -0,0 +1,19 @@
module main

struct Point {
x int
y int
}

struct Holder {
buf [3]Point
}

fn main() {
h := Holder{
buf: [Point{1, 2}, Point{3, 4}, Point{5, 6}]
}
for i in &h.buf {
println(i.x)
}
}