From 7764f2717082a77cff63da24827355c7200c2979 Mon Sep 17 00:00:00 2001
From: ridiculousfish <corydoras@ridiculousfish.com>
Date: Sat, 10 Mar 2018 02:10:40 -0800
Subject: [PATCH] Correct failure to set 'filled' flag in maybe_t constructors

---
 src/fish_tests.cpp | 7 +++++++
 src/maybe.h        | 6 +++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/fish_tests.cpp b/src/fish_tests.cpp
index e2d70a73e..3ccd7ad25 100644
--- a/src/fish_tests.cpp
+++ b/src/fish_tests.cpp
@@ -4472,6 +4472,13 @@ void test_maybe() {
     do_test(m2.missing_or_empty());
     m2 = none();
     do_test(m2.missing_or_empty());
+
+    maybe_t<std::string> m0 = none();
+    maybe_t<std::string> m3("hi");
+    maybe_t<std::string> m4 = m3;
+    do_test(m4 && *m4 == "hi");
+    maybe_t<std::string> m5 = m0;
+    do_test(!m5);
 }
 
 void test_layout_cache() {
diff --git a/src/maybe.h b/src/maybe.h
index 73939471c..898731f9d 100644
--- a/src/maybe.h
+++ b/src/maybe.h
@@ -40,16 +40,16 @@ class maybe_t {
     /* implicit */ maybe_t(const T &v) : filled(true) { new (storage) T(v); }
 
     // Copy constructor.
-    maybe_t(const maybe_t &v) {
+    maybe_t(const maybe_t &v) : filled(v.filled) {
         if (v.filled) {
             new (storage) T(v.value());
         }
     }
 
     // Move constructor.
-    /* implicit */ maybe_t(maybe_t &&v) {
+    /* implicit */ maybe_t(maybe_t &&v) : filled(v.filled) {
         if (v.filled) {
-            *this = std::move(v.value());
+            new (storage) T(std::move(v.value()));
         }
     }