From 361b51cddf2620bdad256cbd0c5e318be4b09c14 Mon Sep 17 00:00:00 2001
From: Nathan Sashihara <21227491+n8sh@users.noreply.github.com>
Date: Wed, 24 Mar 2021 09:12:31 -0700
Subject: [PATCH] Fix Issue 21760 - std.conv.to does not know how to convert a
 string to a std.experimental.checkedint.Checked!T

---
 std/experimental/checkedint.d | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/std/experimental/checkedint.d b/std/experimental/checkedint.d
index 5fb501146..9c7816697 100644
--- a/std/experimental/checkedint.d
+++ b/std/experimental/checkedint.d
@@ -263,7 +263,8 @@ if (isIntegral!T || is(T == Checked!(U, H), U, H))
 {
     import std.algorithm.comparison : among;
     import std.experimental.allocator.common : stateSize;
-    import std.traits : hasMember;
+    import std.range.primitives : isInputRange, ElementType;
+    import std.traits : hasMember, isSomeChar;
 
     /**
     The type of the integral subject to checking.
@@ -378,6 +379,34 @@ if (isIntegral!T || is(T == Checked!(U, H), U, H))
         assert(a == 3 && b == 3);
     }
 
+    /**
+    Construct from a decimal string. The conversion follows the same rules as
+    $(REF to, std, conv) converting a string to the wrapped `T` type.
+
+    Params:
+        str = an $(REF_ALTTEXT input range, isInputRange, std,range,primitives)
+              of characters
+    */
+    this(Range)(Range str)
+    if (isInputRange!Range && isSomeChar!(ElementType!Range))
+    {
+        import std.conv : to;
+
+        this(to!T(str));
+    }
+
+    /**
+    $(REF to, std, conv) can convert a string to a `Checked!T`:
+    */
+    @system unittest
+    {
+        import std.conv : to;
+
+        const a = to!long("1234");
+        const b = to!(Checked!long)("1234");
+        assert(a == b);
+    }
+
     // opCast
     /**
     Casting operator to integral, `bool`, or floating point type. If `Hook`