From 7596b52c1db0016d2c9a3460d58a957bd7160b07 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 29 Apr 2026 21:10:23 +0300
Subject: [PATCH] cgen, markused: fixes

---
 vlib/v/gen/c/utils.v                          |  4 +-
 vlib/v/markused/walker.v                      |  3 ++
 .../generic_fn_instantiation_pruning_test.v   | 51 +++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/vlib/v/gen/c/utils.v b/vlib/v/gen/c/utils.v
index ce9709bbd..1401dee00 100644
--- a/vlib/v/gen/c/utils.v
+++ b/vlib/v/gen/c/utils.v
@@ -387,7 +387,9 @@ fn (mut g Gen) is_expr_smartcast_to_sumtype(expr ast.Expr, expected_sumtype ast.
 	if expr is ast.SelectorExpr {
 		v := scope.find_struct_field(expr.expr.str(), expr.expr_type, expr.field_name)
 		if v != unsafe { nil } && v.smartcasts.len > 0 {
-			return true
+			orig_type := g.unwrap_generic(g.recheck_concrete_type(v.orig_type))
+			resolved_expected_sumtype := g.unwrap_generic(g.recheck_concrete_type(expected_sumtype))
+			return orig_type == resolved_expected_sumtype
 		}
 	} else if expr is ast.Ident {
 		if v := scope.find_var(expr.name) {
diff --git a/vlib/v/markused/walker.v b/vlib/v/markused/walker.v
index dc27c784a..6f2cd3d47 100644
--- a/vlib/v/markused/walker.v
+++ b/vlib/v/markused/walker.v
@@ -3223,6 +3223,9 @@ fn (mut w Walker) mark_generic_body_dependencies_in_stmts(stmts []ast.Stmt) {
 fn (mut w Walker) mark_generic_body_dependencies_in_expr(expr_ ast.Expr) {
 	expr := unsafe { expr_ }
 	match expr {
+		ast.AnonFn {
+			w.mark_generic_body_dependencies_in_stmts(expr.decl.stmts)
+		}
 		ast.CallExpr {
 			w.mark_direct_non_generic_call(expr)
 			w.mark_generic_body_dependencies_in_expr(expr.left)
diff --git a/vlib/v/tests/skip_unused/generic_fn_instantiation_pruning_test.v b/vlib/v/tests/skip_unused/generic_fn_instantiation_pruning_test.v
index 6d158766e..d20e97fc8 100644
--- a/vlib/v/tests/skip_unused/generic_fn_instantiation_pruning_test.v
+++ b/vlib/v/tests/skip_unused/generic_fn_instantiation_pruning_test.v
@@ -124,3 +124,54 @@ fn test_skip_unused_keeps_json2_embedded_struct_decode_helpers() {
 	assert res.output.contains('x__json2__check_required_struct_fields_T_main__Req')
 	assert res.output.contains('x__json2__create_value_from_optional_T_time__Time')
 }
+
+fn test_skip_unused_marks_dependencies_inside_generic_anon_fns() {
+	tmp_dir := os.join_path(os.vtmp_dir(), 'v_generic_anon_fn_dependencies')
+	os.mkdir_all(tmp_dir) or { panic(err) }
+	defer {
+		os.rmdir_all(tmp_dir) or {}
+	}
+	source_path := os.join_path(tmp_dir, 'generic_anon_fn_dependencies.v')
+	binary_path := os.join_path(tmp_dir, 'generic_anon_fn_dependencies')
+	source := [
+		'module main',
+		'',
+		'struct Holder[T] {',
+		'\tdata []T',
+		'}',
+		'',
+		'fn (h &Holder[T]) nmap[T](others []&Holder[T], f fn ([]T) T) T {',
+		'\treturn f([h.data[0], others[0].data[0]])',
+		'}',
+		'',
+		'fn (a &Holder[T]) subtract[T](b &Holder[T]) T {',
+		'\treturn a.nmap([b], fn [T] (xs []T) T {',
+		'\t\tx := xs[0]',
+		'\t\ty := xs[1]',
+		'\t\t$if T is string {',
+		"\t\t\treturn x.replace(y, '')",
+		'\t\t} $else {',
+		'\t\t\treturn x - y',
+		'\t\t}',
+		'\t})',
+		'}',
+		'',
+		'fn unused_string() {',
+		"\ta := &Holder[string]{data: ['abc']}",
+		"\tb := &Holder[string]{data: ['b']}",
+		'\tprintln(a.subtract(b))',
+		'}',
+		'',
+		'fn main() {',
+		'\ta := &Holder[int]{data: [1]}',
+		'\tb := &Holder[int]{data: [2]}',
+		'\tprintln(a.subtract(b))',
+		'}',
+	].join('\n')
+	os.write_file(source_path, source) or { panic(err) }
+	res :=
+		os.execute('${os.quoted_path(vexe)} -d no_backtrace -o ${os.quoted_path(binary_path)} ${os.quoted_path(source_path)}')
+	if res.exit_code != 0 {
+		panic(res.output)
+	}
+}
-- 
2.39.5