From 240cf2e0b11b80ed5ba5c900af9127f87fcfbbf1 Mon Sep 17 00:00:00 2001
From: MoonlightSentinel <moonlightsentinel@disroot.org>
Date: Sun, 19 Apr 2020 11:53:20 +0200
Subject: [PATCH] Fix Issue 20748 - Deprecation for assert using shared type
 and checkaction=context

---
 src/core/internal/dassert.d       | 21 ++++++++++++++++++++-
 test/exceptions/src/assert_fail.d |  4 ++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index ff14840ca3d..e49f30b9419 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 = 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 22dbf09e314..b8269c5179d 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");
@@ -135,6 +136,9 @@ 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()()