From cfe4c6fc95435b54db0cb6f9d890773015fa502f Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Sat, 4 Dec 2021 17:26:08 +0100
Subject: [PATCH] =?UTF-8?q?Ensure=20that=20=3D=3F=20works=20with=20types?=
 =?UTF-8?q?=20that=20do=20not=20have=20a=20default=20value?=

---
 questionable/binding.nim     | 10 +++++++---
 testmodules/nim.cfg          |  2 ++
 testmodules/options/test.nim | 14 ++++++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 testmodules/nim.cfg

diff --git a/questionable/binding.nim b/questionable/binding.nim
index a88ffa7..da01187 100644
--- a/questionable/binding.nim
+++ b/questionable/binding.nim
@@ -4,15 +4,19 @@ import std/macros
 proc option[T](option: Option[T]): Option[T] =
   option
 
+proc placeholder(T: type): T =
+  discard
+
 template bindLet(name, expression): bool =
   let option = expression.option
-  const default = typeof(option.unsafeGet()).default
-  let name {.used.} = if option.isSome: option.unsafeGet() else: default
+  type T = typeof(option.unsafeGet())
+  let name {.used.} = if option.isSome: option.unsafeGet() else: placeholder(T)
   option.isSome
 
 template bindVar(name, expression): bool =
   let option = expression.option
-  var name {.used.} : typeof(option.unsafeGet())
+  type T = typeof(option.unsafeGet())
+  var name {.used.} : T = placeholder(T)
   if option.isSome:
     name = option.unsafeGet()
   option.isSome
diff --git a/testmodules/nim.cfg b/testmodules/nim.cfg
new file mode 100644
index 0000000..222cb3d
--- /dev/null
+++ b/testmodules/nim.cfg
@@ -0,0 +1,2 @@
+--warningAsError[UnsafeDefault]:"on"
+--warningAsError[ProveInit]:"on"
diff --git a/testmodules/options/test.nim b/testmodules/options/test.nim
index 3733169..ece94fe 100644
--- a/testmodules/options/test.nim
+++ b/testmodules/options/test.nim
@@ -162,6 +162,20 @@ suite "optionals":
 
     check called
 
+  test "=? works with types that do not have a default value":
+    type NoDefault {.requiresInit.} = distinct int
+    proc `==`(a,b: NoDefault): bool {.borrow.}
+
+    if a =? some NoDefault(42):
+      check a == NoDefault(42)
+    else:
+      fail()
+
+    if var a =? some NoDefault(42):
+      check a == NoDefault(42)
+    else:
+      fail()
+
   test "without statement can be used for early returns":
     proc test1 =
       without a =? 42.some: