From f25dfa9d8c0f4d7b920d00c582294e639d308c51 Mon Sep 17 00:00:00 2001
From: Swastik Baranwal <swstkbaranwal@gmail.com>
Date: Mon, 24 Oct 2022 14:23:35 +0530
Subject: [PATCH] checker: add error for unwrapped result in infix expr
 (#16175)

---
 vlib/v/checker/infix.v                              | 12 +++++++++---
 vlib/v/checker/tests/unwrapped_result_infix_err.out |  8 ++++++++
 vlib/v/checker/tests/unwrapped_result_infix_err.vv  | 12 ++++++++++++
 3 files changed, 29 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/checker/tests/unwrapped_result_infix_err.out
 create mode 100644 vlib/v/checker/tests/unwrapped_result_infix_err.vv

diff --git a/vlib/v/checker/infix.v b/vlib/v/checker/infix.v
index 2817b24e4b..cd12b1a2e7 100644
--- a/vlib/v/checker/infix.v
+++ b/vlib/v/checker/infix.v
@@ -613,12 +613,18 @@ pub fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 	// TODO move this to symmetric_check? Right now it would break `return 0` for `fn()?int `
 	left_is_optional := left_type.has_flag(.optional)
 	right_is_optional := right_type.has_flag(.optional)
-	if left_is_optional && right_is_optional {
-		c.error('unwrapped optionals cannot be used in an infix expression', left_right_pos)
-	} else if left_is_optional || right_is_optional {
+	if left_is_optional || right_is_optional {
 		opt_infix_pos := if left_is_optional { left_pos } else { right_pos }
 		c.error('unwrapped optional cannot be used in an infix expression', opt_infix_pos)
 	}
+
+	left_is_result := left_type.has_flag(.result)
+	right_is_result := right_type.has_flag(.result)
+	if left_is_result || right_is_result {
+		opt_infix_pos := if left_is_result { left_pos } else { right_pos }
+		c.error('unwrapped result cannot be used in an infix expression', opt_infix_pos)
+	}
+
 	// Dual sides check (compatibility check)
 	if node.left !is ast.ComptimeCall && node.right !is ast.ComptimeCall {
 		if !(c.symmetric_check(left_type, right_type) && c.symmetric_check(right_type, left_type))
diff --git a/vlib/v/checker/tests/unwrapped_result_infix_err.out b/vlib/v/checker/tests/unwrapped_result_infix_err.out
new file mode 100644
index 0000000000..69de1f98dd
--- /dev/null
+++ b/vlib/v/checker/tests/unwrapped_result_infix_err.out
@@ -0,0 +1,8 @@
+vlib/v/checker/tests/unwrapped_result_infix_err.vv:7:9: error: unwrapped result cannot be used in an infix expression
+    5 | fn g() ! {
+    6 |     assert f('1')! == true
+    7 |     assert f('1') == true
+      |            ~~~~~~
+    8 | }
+    9 |
+
diff --git a/vlib/v/checker/tests/unwrapped_result_infix_err.vv b/vlib/v/checker/tests/unwrapped_result_infix_err.vv
new file mode 100644
index 0000000000..06e423231b
--- /dev/null
+++ b/vlib/v/checker/tests/unwrapped_result_infix_err.vv
@@ -0,0 +1,12 @@
+fn f(k string) !bool {
+	return true
+}
+
+fn g() ! {
+	assert f('1')! == true
+	assert f('1') == true
+}
+
+fn main() {
+	g()!
+}