From 350846e11bc67fc7e7b183974e6e7cbd19cd8258 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 28 Sep 2024 06:03:22 -0300
Subject: [PATCH] checker: add an error for returning an `any` value in pure V
 code (prevents invalid cgen) (fix #12623) (#22334)

---
 vlib/v/checker/fn.v                          |  3 ++
 vlib/v/checker/tests/any_return_type_err.out | 42 ++++++++++++++++++++
 vlib/v/checker/tests/any_return_type_err.vv  | 30 ++++++++++++++
 3 files changed, 75 insertions(+)
 create mode 100644 vlib/v/checker/tests/any_return_type_err.out
 create mode 100644 vlib/v/checker/tests/any_return_type_err.vv

diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 6e82c43c9..c3a468986 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -118,6 +118,9 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 			node.return_type_pos)
 	}
 	if node.return_type != ast.void_type {
+		if node.language == .v && node.return_type.clear_option_and_result() == ast.any_type {
+			c.error('cannot use type `any` here', node.return_type_pos)
+		}
 		if ct_attr_idx := node.attrs.find_comptime_define() {
 			sexpr := node.attrs[ct_attr_idx].ct_expr.str()
 			c.error('only functions that do NOT return values can have `[if ${sexpr}]` tags',
diff --git a/vlib/v/checker/tests/any_return_type_err.out b/vlib/v/checker/tests/any_return_type_err.out
new file mode 100644
index 000000000..be724836a
--- /dev/null
+++ b/vlib/v/checker/tests/any_return_type_err.out
@@ -0,0 +1,42 @@
+vlib/v/checker/tests/any_return_type_err.vv:4:19: error: cannot use type `any` here
+    2 | }
+    3 | 
+    4 | fn (f Test) abc() any {
+      |                   ~~~
+    5 |     return 0
+    6 | }
+vlib/v/checker/tests/any_return_type_err.vv:8:20: error: cannot use type `any` here
+    6 | }
+    7 | 
+    8 | fn (f Test) abc2() ?any {
+      |                    ~~~~
+    9 |     return 0
+   10 | }
+vlib/v/checker/tests/any_return_type_err.vv:12:20: error: cannot use type `any` here
+   10 | }
+   11 | 
+   12 | fn (f Test) abc3() !any {
+      |                    ~~~~
+   13 |     return 0
+   14 | }
+vlib/v/checker/tests/any_return_type_err.vv:16:10: error: cannot use type `any` here
+   14 | }
+   15 | 
+   16 | fn foo() any {
+      |          ~~~
+   17 |     return 3
+   18 | }
+vlib/v/checker/tests/any_return_type_err.vv:20:11: error: cannot use type `any` here
+   18 | }
+   19 | 
+   20 | fn foo2() ?any {
+      |           ~~~~
+   21 |     return 3
+   22 | }
+vlib/v/checker/tests/any_return_type_err.vv:24:11: error: cannot use type `any` here
+   22 | }
+   23 | 
+   24 | fn foo3() !any {
+      |           ~~~~
+   25 |     return 3
+   26 | }
diff --git a/vlib/v/checker/tests/any_return_type_err.vv b/vlib/v/checker/tests/any_return_type_err.vv
new file mode 100644
index 000000000..baa898d0d
--- /dev/null
+++ b/vlib/v/checker/tests/any_return_type_err.vv
@@ -0,0 +1,30 @@
+struct Test {
+}
+
+fn (f Test) abc() any {
+	return 0
+}
+
+fn (f Test) abc2() ?any {
+	return 0
+}
+
+fn (f Test) abc3() !any {
+	return 0
+}
+
+fn foo() any {
+	return 3
+}
+
+fn foo2() ?any {
+	return 3
+}
+
+fn foo3() !any {
+	return 3
+}
+
+fn main() {
+	println('any ${foo}')
+}
-- 
2.39.5