From 599cac7b28af6f4593b12a1207f5bf956a29855a Mon Sep 17 00:00:00 2001
From: MoonlightSentinel <moonlightsentinel@disroot.org>
Date: Tue, 21 Apr 2020 22:01:00 +0200
Subject: [PATCH 1/2] Fix Issue 20757 - checkaction=context prints characters
 as integers

---
 src/core/internal/dassert.d       | 20 ++++++++++++++++----
 test/exceptions/src/assert_fail.d |  4 ++++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index afb9136a6bb..a3224787d72 100644
--- a/src/core/internal/dassert.d
+++ b/src/core/internal/dassert.d
@@ -95,10 +95,22 @@ private string miniFormat(V)(const scope ref V v)
     }
     else static if (__traits(isIntegral, V))
     {
-        enum printfFormat = getPrintfFormat!V;
-        char[20] val;
-        const len = sprintf(&val[0], printfFormat, v);
-        return val.idup[0 .. len];
+        static if (is(V == char))
+        {
+            return ['\'', v, '\''];
+        }
+        else static if (is(V == wchar) || is(V == dchar))
+        {
+            import core.internal.utf: toUTF8;
+            return toUTF8(['\'', v, '\'']);
+        }
+        else
+        {
+            enum printfFormat = getPrintfFormat!V;
+            char[20] val;
+            const len = sprintf(&val[0], printfFormat, v);
+            return val.idup[0 .. len];
+        }
     }
     else static if (__traits(isFloating, V))
     {
diff --git a/test/exceptions/src/assert_fail.d b/test/exceptions/src/assert_fail.d
index d7de373b5b4..4d0f79e7d7e 100644
--- a/test/exceptions/src/assert_fail.d
+++ b/test/exceptions/src/assert_fail.d
@@ -63,6 +63,10 @@ void testStrings()
     // https://issues.dlang.org/show_bug.cgi?id=20322
     test("left"w, "right"w, `"left" != "right"`);
     test("left"d, "right"d, `"left" != "right"`);
+
+    test('A', 'B', "'A' != 'B'");
+    test(wchar('❤'), wchar('∑'), "'❤' != '∑'");
+    test(dchar('❤'), dchar('∑'), "'❤' != '∑'");
 }
 
 void testToString()()

From 70741bcb114ca86a1126d3534576d7b386a26d61 Mon Sep 17 00:00:00 2001
From: MoonlightSentinel <moonlightsentinel@disroot.org>
Date: Wed, 22 Apr 2020 00:28:53 +0200
Subject: [PATCH 2/2] Handle invalid code points

---
 src/core/internal/dassert.d       | 17 ++++++++++++++---
 test/exceptions/src/assert_fail.d |  5 +++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index a3224787d72..4aa1371cfc6 100644
--- a/src/core/internal/dassert.d
+++ b/src/core/internal/dassert.d
@@ -97,12 +97,23 @@ private string miniFormat(V)(const scope ref V v)
     {
         static if (is(V == char))
         {
-            return ['\'', v, '\''];
+            // Avoid invalid code points
+            if (v < 0x7F)
+                return ['\'', v, '\''];
+
+            uint tmp = v;
+            return "cast(char) " ~ miniFormat(tmp);
         }
         else static if (is(V == wchar) || is(V == dchar))
         {
-            import core.internal.utf: toUTF8;
-            return toUTF8(['\'', v, '\'']);
+            import core.internal.utf: isValidDchar, toUTF8;
+
+            // Avoid invalid code points
+            if (isValidDchar(v))
+                return toUTF8(['\'', v, '\'']);
+
+            uint tmp = v;
+            return "cast(" ~ V.stringof ~ ") " ~ miniFormat(tmp);
         }
         else
         {
diff --git a/test/exceptions/src/assert_fail.d b/test/exceptions/src/assert_fail.d
index 4d0f79e7d7e..c4983e51de2 100644
--- a/test/exceptions/src/assert_fail.d
+++ b/test/exceptions/src/assert_fail.d
@@ -67,6 +67,11 @@ void testStrings()
     test('A', 'B', "'A' != 'B'");
     test(wchar('❤'), wchar('∑'), "'❤' != '∑'");
     test(dchar('❤'), dchar('∑'), "'❤' != '∑'");
+
+    // Detect invalid code points
+    test(char(255), 'B', "cast(char) 255 != 'B'");
+    test(wchar(0xD888), wchar('∑'), "cast(wchar) 55432 != '∑'");
+    test(dchar(0xDDDD), dchar('∑'), "cast(dchar) 56797 != '∑'");
 }
 
 void testToString()()