From f77c968cf841046238eb37f54600cda201f09ce2 Mon Sep 17 00:00:00 2001
From: Ryan Liptak <squeek502@hotmail.com>
Date: Wed, 8 Jul 2020 00:53:19 -0700
Subject: [PATCH] langref: Add test case for "if error union with optional"

This is an edge case that isn't too uncommon but is rather confusing to try to deduce without documentation, since it feels like `else` is being overloaded in this scenario and there's no obvious 'correct' behavior here. This just adds a test demonstrating how Zig currently behaves in this scenario.
---
 doc/langref.html.in | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/doc/langref.html.in b/doc/langref.html.in
index 1e4d993fe9..032e05d600 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -3861,6 +3861,32 @@ test "if error union" {
         unreachable;
     }
 }
+
+test "if error union with optional" {
+    // If expressions test for errors before unwrapping optionals.
+    // The |optional_value| capture's type is ?u32.
+
+    const a: anyerror!?u32 = 0;
+    if (a) |optional_value| {
+        assert(optional_value.? == 0);
+    } else |err| {
+        unreachable;
+    }
+
+    const b: anyerror!?u32 = null;
+    if (b) |optional_value| {
+        assert(optional_value == null);
+    } else |err| {
+        unreachable;
+    }
+
+    const c: anyerror!?u32 = error.BadValue;
+    if (c) |optional_value| {
+        unreachable;
+    } else |err| {
+        assert(err == error.BadValue);
+    }
+}
       {#code_end#}
       {#see_also|Optionals|Errors#}
       {#header_close#}