From 287d33e2ab2764b243ed3088b7a06a116688e477 Mon Sep 17 00:00:00 2001
From: Hitalo Souza <enghitalo@gmail.com>
Date: Sun, 21 Jun 2026 06:31:32 -0300
Subject: [PATCH] wasm: resolve fixed-array `.len` instead of aborting with
 "could not find field len" (#27518)

---
 vlib/v/gen/wasm/gen.v               |  8 +++++++-
 vlib/v/gen/wasm/tests/arrays.vv     | 10 ++++++++++
 vlib/v/gen/wasm/tests/arrays.vv.out |  3 +++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/vlib/v/gen/wasm/gen.v b/vlib/v/gen/wasm/gen.v
index 916e488d0..4374f6215 100644
--- a/vlib/v/gen/wasm/gen.v
+++ b/vlib/v/gen/wasm/gen.v
@@ -1016,7 +1016,13 @@ pub fn (mut g Gen) expr(node ast.Expr, expected ast.Type) {
 			g.get(v)
 		}
 		ast.SelectorExpr {
-			if v := g.get_var_from_expr(node) {
+			final := g.table.final_sym(node.expr_type)
+			if node.field_name == 'len' && final.info is ast.ArrayFixed {
+				// a fixed array's `.len` is a compile-time constant; the checker
+				// types it as `int` but emits no field, so resolve it here rather
+				// than aborting in get_field_offset ("could not find field len").
+				g.func.i32_const(i32(final.info.size))
+			} else if v := g.get_var_from_expr(node) {
 				if g.needs_address {
 					if !v.is_address {
 						g.v_error("cannot take the address of a value that doesn't live on the stack. this is a current limitation.",
diff --git a/vlib/v/gen/wasm/tests/arrays.vv b/vlib/v/gen/wasm/tests/arrays.vv
index 6a05c881f..4d025fca5 100644
--- a/vlib/v/gen/wasm/tests/arrays.vv
+++ b/vlib/v/gen/wasm/tests/arrays.vv
@@ -62,6 +62,13 @@ fn selector_index_assign() {
 	println(app.frame[app.idx])
 }
 
+fn fixed_array_len() {
+	a := [10, 12, 150]!
+	println(a.len)
+	b := [8]int{}
+	println(b.len)
+}
+
 fn main() {
 	println('--- static_arrays()')
 	a, b, c := static_arrays()
@@ -83,4 +90,7 @@ fn main() {
 
 	println('--- selector_index_assign()')
 	selector_index_assign()
+
+	println('--- fixed_array_len()')
+	fixed_array_len()
 }
diff --git a/vlib/v/gen/wasm/tests/arrays.vv.out b/vlib/v/gen/wasm/tests/arrays.vv.out
index f020c11b5..53eaec65a 100644
--- a/vlib/v/gen/wasm/tests/arrays.vv.out
+++ b/vlib/v/gen/wasm/tests/arrays.vv.out
@@ -16,3 +16,6 @@
 0
 123
 123
+--- fixed_array_len()
+3
+8
-- 
2.39.5