From 62ae7ad99b00abe0d582a781d5154579e48108c3 Mon Sep 17 00:00:00 2001
From: MoonlightSentinel <moonlightsentinel@disroot.org>
Date: Sun, 19 Apr 2020 11:53:20 +0200
Subject: [PATCH 1/2] Fix Issue 20748 - Deprecation for assert using shared
 type and checkaction=context

---
 src/core/internal/dassert.d       | 21 ++++++++++++++++++++-
 test/exceptions/src/assert_fail.d |  7 +++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index ff14840ca3..0b56d03ffc 100644
--- a/src/core/internal/dassert.d
+++ b/src/core/internal/dassert.d
@@ -75,7 +75,21 @@ private string miniFormat(V)(const ref V v)
     import core.internal.traits: isAggregateType;
     import core.stdc.stdio : sprintf;
     import core.stdc.string : strlen;
-    static if (is(V : bool))
+
+    static if (is(V == shared T, T))
+    {
+        // Use atomics to avoid race conditions whenever possible
+        static if (__traits(compiles, atomicLoad(v)))
+        {
+            T tmp = cast(T) atomicLoad(v);
+            return miniFormat(tmp);
+        }
+        else
+        {   // Fall back to a simple cast - we're violating the type system anyways
+            return miniFormat(*cast(T*) &v);
+        }
+    }
+    else static if (is(V == bool))
     {
         return v ? "true" : "false";
     }
@@ -189,6 +203,11 @@ private string miniFormat(V)(const ref V v)
     }
 }
 
+// This should be a local import in miniFormat but fails with a cyclic dependency error
+// core.thread.osthread -> core.time -> object -> core.internal.array.capacity
+// -> core.atomic -> core.thread -> core.thread.osthread
+import core.atomic : atomicLoad;
+
 // Inverts a comparison token for use in _d_assert_fail
 private string invertCompToken(string comp)
 {
diff --git a/test/exceptions/src/assert_fail.d b/test/exceptions/src/assert_fail.d
index 22dbf09e31..64a8352c7b 100644
--- a/test/exceptions/src/assert_fail.d
+++ b/test/exceptions/src/assert_fail.d
@@ -29,6 +29,7 @@ void testIntegers()()
     test(uint.min, uint.max, "0 != 4294967295");
     test(long.min, long.max, "-9223372036854775808 != 9223372036854775807");
     test(ulong.min, ulong.max, "0 != 18446744073709551615");
+    test(shared(ulong).min, shared(ulong).max, "0 != 18446744073709551615");
 
     int testFun() { return 1; }
     test(testFun(), 2, "1 != 2");
@@ -79,6 +80,9 @@ void testToString()()
     }
     test(new Foo("a"), new Foo("b"), "Foo(a) != Foo(b)");
 
+    scope f = cast(shared) new Foo("a");
+    test!"!="(f, f, "Foo(a) == Foo(a)");
+
     // Verifiy that the const toString is selected if present
     static struct Overloaded
     {
@@ -135,6 +139,9 @@ void testStruct()()
 
     NoCopy n;
     test(_d_assert_fail!"!="(n, n), "NoCopy() == NoCopy()");
+
+    shared NoCopy sn;
+    test(_d_assert_fail!"!="(sn, sn), "NoCopy() == NoCopy()");
 }
 
 void testAA()()

From a045839291d07a9366d42920f1cf30b030d9fc35 Mon Sep 17 00:00:00 2001
From: MoonlightSentinel <moonlightsentinel@disroot.org>
Date: Sun, 19 Apr 2020 13:54:52 +0200
Subject: [PATCH 2/2] Fix Issue 20750 - checkaction=context segfaults for null
 references

---
 src/core/internal/dassert.d       | 19 +++++++++++++------
 test/exceptions/src/assert_fail.d |  3 +++
 2 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index ff14840ca3..1aa730186a 100644
--- a/src/core/internal/dassert.d
+++ b/src/core/internal/dassert.d
@@ -97,14 +97,21 @@ private string miniFormat(V)(const ref V v)
     {
         return "`null`";
     }
-    else static if (__traits(compiles, { string s = v.toString(); }))
-    {
-        return v.toString();
-    }
-    // Non-const toString(), e.g. classes inheriting from Object
+    // toString() isn't always const, e.g. classes inheriting from Object
     else static if (__traits(compiles, { string s = V.init.toString(); }))
     {
-        return (cast() v).toString();
+        // Object references / struct pointers may be null
+        static if (is(V == class) || is(V == interface) || is(V == U*, U))
+        {
+            if (v is null)
+                return "`null`";
+        }
+
+        // Prefer const overload of toString
+        static if (__traits(compiles, { string s = v.toString(); }))
+            return v.toString();
+        else
+            return (cast() v).toString();
     }
     // Static arrays or slices (but not aggregates with `alias this`)
     else static if (is(V : U[], U) && !isAggregateType!V)
diff --git a/test/exceptions/src/assert_fail.d b/test/exceptions/src/assert_fail.d
index 22dbf09e31..5513c08630 100644
--- a/test/exceptions/src/assert_fail.d
+++ b/test/exceptions/src/assert_fail.d
@@ -94,6 +94,9 @@ void testToString()()
     }
 
     test!"!="(Overloaded(), Overloaded(), "Const == Const");
+
+    Foo fnull = null;
+    test!"!is"(fnull, fnull, "`null` is `null`");
 }