From 8ad14cab12458eaa40afb8ec6698b2e47d66c117 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 15 Apr 2026 05:26:24 +0300
Subject: [PATCH] checker: fix anonymous generic struct shadow variable (fixes
 #15535)

---
 vlib/v/checker/assign.v                          |  3 ++-
 vlib/v/checker/fn.v                              | 11 +++++++++++
 .../tests/assign_generic_closure_fn_err.out      |  7 +++++++
 .../tests/assign_generic_closure_fn_err.vv       | 16 ++++++++++++++++
 4 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 vlib/v/checker/tests/assign_generic_closure_fn_err.out
 create mode 100644 vlib/v/checker/tests/assign_generic_closure_fn_err.vv

diff --git a/vlib/v/checker/assign.v b/vlib/v/checker/assign.v
index b5a5e9781..9c027cd41 100644
--- a/vlib/v/checker/assign.v
+++ b/vlib/v/checker/assign.v
@@ -151,7 +151,8 @@ fn (mut c Checker) assign_stmt(mut node ast.AssignStmt) {
 			c.error('cannot use `none` in `unsafe` blocks', right.expr.pos)
 		}
 		if mut right is ast.AnonFn {
-			if right.decl.generic_names.len > 0 && right.inherited_vars.len == 0 {
+			if right.decl.generic_names.len > 0 && (right.inherited_vars.len == 0
+				|| !c.generic_anon_fn_can_use_current_context(right.decl.generic_names)) {
 				c.error('cannot assign generic function to a variable', right.decl.pos)
 			}
 		}
diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 1a98be1de..2e74afa37 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -143,6 +143,17 @@ fn (mut c Checker) effective_fn_generic_names(node &ast.FnDecl) []string {
 	return c.table.generic_type_names(node.receiver.typ)
 }
 
+fn (mut c Checker) generic_anon_fn_can_use_current_context(generic_names []string) bool {
+	if generic_names.len == 0 || c.table.cur_fn == unsafe { nil } {
+		return false
+	}
+	current_generic_names := c.effective_fn_generic_names(c.table.cur_fn)
+	if current_generic_names.len == 0 {
+		return false
+	}
+	return generic_names.all(it in current_generic_names)
+}
+
 fn (mut c Checker) receiver_requires_generic_names(node &ast.FnDecl) bool {
 	if !node.is_method {
 		return false
diff --git a/vlib/v/checker/tests/assign_generic_closure_fn_err.out b/vlib/v/checker/tests/assign_generic_closure_fn_err.out
new file mode 100644
index 000000000..f6d9e3bf6
--- /dev/null
+++ b/vlib/v/checker/tests/assign_generic_closure_fn_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/assign_generic_closure_fn_err.vv:12:10: error: cannot assign generic function to a variable
+   10 | fn main() {
+   11 |     mut cmd := Cmd[string]{}
+   12 |     anon := fn [mut cmd] [T]() {
+      |             ~~~~~~~~~~~~~~~~~~~~
+   13 |         use_cmd(mut cmd)
+   14 |     }
diff --git a/vlib/v/checker/tests/assign_generic_closure_fn_err.vv b/vlib/v/checker/tests/assign_generic_closure_fn_err.vv
new file mode 100644
index 000000000..97c7ecd7f
--- /dev/null
+++ b/vlib/v/checker/tests/assign_generic_closure_fn_err.vv
@@ -0,0 +1,16 @@
+struct Cmd[T] {
+mut:
+	val T
+}
+
+fn use_cmd[T](mut cmd Cmd[T]) {
+	_ = cmd
+}
+
+fn main() {
+	mut cmd := Cmd[string]{}
+	anon := fn [mut cmd] [T]() {
+		use_cmd(mut cmd)
+	}
+	anon()
+}
-- 
2.39.5