From 0e4ae765077ea3c91fe30d904998a163d99293f3 Mon Sep 17 00:00:00 2001
From: Surman The Dead <70163032+SurmanPP@users.noreply.github.com>
Date: Thu, 15 Jan 2026 06:01:40 +0100
Subject: [PATCH] wasm: fix size of pointers in structs (#26357)

---
 vlib/v/gen/wasm/serialise/serialise.v |  4 ++++
 vlib/v/gen/wasm/tests/misc.vv         | 17 +++++++++++++++++
 vlib/v/gen/wasm/tests/misc.vv.out     |  3 +++
 3 files changed, 24 insertions(+)

diff --git a/vlib/v/gen/wasm/serialise/serialise.v b/vlib/v/gen/wasm/serialise/serialise.v
index bd9524c5e..2424239b9 100644
--- a/vlib/v/gen/wasm/serialise/serialise.v
+++ b/vlib/v/gen/wasm/serialise/serialise.v
@@ -58,6 +58,10 @@ pub fn (mut p Pool) type_struct_info(typ ast.Type) ?StructInfo {
 }
 
 pub fn (mut p Pool) type_size(typ ast.Type) (int, int) {
+	if typ.nr_muls() > 0 {
+		return p.table.pointer_size, p.table.pointer_size
+	}
+
 	ts := p.table.sym(typ)
 	if ts.size != -1 && typ.idx() in p.structs {
 		return ts.size, ts.align
diff --git a/vlib/v/gen/wasm/tests/misc.vv b/vlib/v/gen/wasm/tests/misc.vv
index 076cb1678..9af617255 100644
--- a/vlib/v/gen/wasm/tests/misc.vv
+++ b/vlib/v/gen/wasm/tests/misc.vv
@@ -82,7 +82,24 @@ fn run_defer() {
 	defer_if(false)
 }
 
+struct HasPointers {
+	a   int
+	msg &string
+pub mut:
+	same &HasPointers
+}
+
+fn ptr_in_struct() {
+	msg := 'pointer in struct'
+	mut s := HasPointers{1234, &msg, unsafe { nil }}
+	println(*s.msg)
+	s.same = &s
+	println(*&int(voidptr(s.same.a))) // FIXME: wont work without casts
+}
+
 fn main() {
+	println('ptr_in_struct')
+	ptr_in_struct()
 	println('ptr_arith')
 	ptr_arith()
 	run_defer()
diff --git a/vlib/v/gen/wasm/tests/misc.vv.out b/vlib/v/gen/wasm/tests/misc.vv.out
index cfcfbde57..5398c2dd7 100644
--- a/vlib/v/gen/wasm/tests/misc.vv.out
+++ b/vlib/v/gen/wasm/tests/misc.vv.out
@@ -1,3 +1,6 @@
+ptr_in_struct
+pointer in struct
+1234
 ptr_arith
 12
 14
-- 
2.39.5