From a187a4abb3c902b1e1be9fbf629b54c2e3bc8358 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Wed, 10 Mar 2021 19:53:23 +0800
Subject: [PATCH] checker: check non-optional fn return or_block (#9227)

---
 vlib/v/checker/checker.v                  |  9 +++++++++
 vlib/v/checker/tests/fn_return_or_err.out |  7 +++++++
 vlib/v/checker/tests/fn_return_or_err.vv  | 13 +++++++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 vlib/v/checker/tests/fn_return_or_err.out
 create mode 100644 vlib/v/checker/tests/fn_return_or_err.vv

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 4d0dee42a4..295e46b3ee 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -3693,6 +3693,15 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 		}
 		ast.CallExpr {
 			mut ret_type := c.call_expr(mut node)
+			if !ret_type.has_flag(.optional) {
+				if node.or_block.kind == .block {
+					c.error('unexpected `or` block, the function `$node.name` does not return an optional',
+						node.or_block.pos)
+				} else if node.or_block.kind == .propagate {
+					c.error('unexpected `?`, the function `$node.name` does not return an optional',
+						node.or_block.pos)
+				}
+			}
 			if ret_type.has_flag(.optional) && node.or_block.kind != .absent {
 				ret_type = ret_type.clear_flag(.optional)
 			}
diff --git a/vlib/v/checker/tests/fn_return_or_err.out b/vlib/v/checker/tests/fn_return_or_err.out
new file mode 100644
index 0000000000..ebb4494d27
--- /dev/null
+++ b/vlib/v/checker/tests/fn_return_or_err.out
@@ -0,0 +1,7 @@
+vlib/v/checker/tests/fn_return_or_err.vv:6:17: error: unexpected `or` block, the function `pop` does not return an optional
+    4 |
+    5 | pub fn next(mut v []Typ) Typ {
+    6 |     return v.pop() or { Typ{} }
+      |                    ~~~~~~~~~~~~
+    7 | }
+    8 |
diff --git a/vlib/v/checker/tests/fn_return_or_err.vv b/vlib/v/checker/tests/fn_return_or_err.vv
new file mode 100644
index 0000000000..c303b0aa69
--- /dev/null
+++ b/vlib/v/checker/tests/fn_return_or_err.vv
@@ -0,0 +1,13 @@
+module main
+
+pub struct Typ {}
+
+pub fn next(mut v []Typ) Typ {
+	return v.pop() or { Typ{} }
+}
+
+fn main() {
+	mut v := [Typ{}]
+	last := next(mut v)
+	println('$last')
+}