From 73caa8dff5ff82eb4589f3c27e7e0b5cd3fd9b35 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Wed, 14 Feb 2024 18:22:55 -0300
Subject: [PATCH] checker: fix if branch option type mismatch (fix #20809)
 (#20830)

---
 vlib/v/checker/if.v                             | 15 ++++++++++++---
 vlib/v/checker/tests/if_mismatch_option_err.out | 12 ++++++++++++
 vlib/v/checker/tests/if_mismatch_option_err.vv  |  9 +++++++++
 3 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/checker/tests/if_mismatch_option_err.out
 create mode 100644 vlib/v/checker/tests/if_mismatch_option_err.vv

diff --git a/vlib/v/checker/if.v b/vlib/v/checker/if.v
index af48f98f1..56a90d9a0 100644
--- a/vlib/v/checker/if.v
+++ b/vlib/v/checker/if.v
@@ -467,10 +467,19 @@ fn (mut c Checker) if_expr(mut node ast.IfExpr) ast.Type {
 							node.pos)
 					} else {
 						if c.inside_assign && node.is_expr && !node.typ.has_flag(.shared_f)
-							&& stmt.typ.is_ptr() != node.typ.is_ptr()
 							&& stmt.typ != ast.voidptr_type {
-							c.error('mismatched types `${c.table.type_to_str(node.typ)}` and `${c.table.type_to_str(stmt.typ)}`',
-								node.pos)
+							if stmt.typ.is_ptr() != node.typ.is_ptr() {
+								c.error('mismatched types `${c.table.type_to_str(node.typ)}` and `${c.table.type_to_str(stmt.typ)}`',
+									node.pos)
+							} else if stmt.typ != ast.none_type {
+								if !node.typ.has_flag(.option) && stmt.typ.has_flag(.option) {
+									c.error('mismatched types `${c.table.type_to_str(node.typ)}` and `${c.table.type_to_str(stmt.typ)}`',
+										node.pos)
+								} else if !node.typ.has_flag(.result) && stmt.typ.has_flag(.result) {
+									c.error('mismatched types `${c.table.type_to_str(node.typ)}` and `${c.table.type_to_str(stmt.typ)}`',
+										node.pos)
+								}
+							}
 						}
 					}
 				} else if !node.is_comptime && stmt !in [ast.Return, ast.BranchStmt] {
diff --git a/vlib/v/checker/tests/if_mismatch_option_err.out b/vlib/v/checker/tests/if_mismatch_option_err.out
new file mode 100644
index 000000000..00ea6a176
--- /dev/null
+++ b/vlib/v/checker/tests/if_mismatch_option_err.out
@@ -0,0 +1,12 @@
+vlib/v/checker/tests/if_mismatch_option_err.vv:8:2: warning: unused variable: `operation`
+    6 | fn main() {
+    7 |     operation_name := 'get_area'
+    8 |     operation := if o := Operation.from(operation_name) { o } else { ?Operation(none) }
+      |     ~~~~~~~~~
+    9 | }
+vlib/v/checker/tests/if_mismatch_option_err.vv:8:15: error: mismatched types `Operation` and `?Operation`
+    6 | fn main() {
+    7 |     operation_name := 'get_area'
+    8 |     operation := if o := Operation.from(operation_name) { o } else { ?Operation(none) }
+      |                  ~~
+    9 | }
diff --git a/vlib/v/checker/tests/if_mismatch_option_err.vv b/vlib/v/checker/tests/if_mismatch_option_err.vv
new file mode 100644
index 000000000..58f177eb2
--- /dev/null
+++ b/vlib/v/checker/tests/if_mismatch_option_err.vv
@@ -0,0 +1,9 @@
+enum Operation {
+	get_area
+	get_sector
+}
+
+fn main() {
+	operation_name := 'get_area'
+	operation := if o := Operation.from(operation_name) { o } else { ?Operation(none) }
+}
\ No newline at end of file
-- 
2.39.5