Fix Issue 20066 - Assertion on void[] does not compile with -checkaction=context

Author: wilzbach

src/core/internal/dassert.d

@@ -58,10 +58,20 @@ auto miniFormat(V)(V v)
         const len = sprintf(&val[0], "%g", v);
         return val.idup[0 .. len];
     }
+    // special-handling for void-arrays
+    else static if (is(V == typeof(null)))
+    {
+        return "`null`";
+    }
     else static if (__traits(compiles, { string s = V.init.toString(); }))
     {
         return v.toString();
     }
+    // special-handling for void-arrays
+    else static if (is(V == void[]))
+    {
+        return "";
+    }
     // anything string-like
     else static if (__traits(compiles, V.init ~ ""))
     {

test/exceptions/src/assert_fail.d

@@ -119,6 +119,17 @@ void testAttributes() @safe pure @nogc nothrow
     assert(a == 0);
 }
 
+// https://issues.dlang.org/show_bug.cgi?id=20066
+void testVoidArray()()
+{
+    assert([] is null);
+    assert(null is null);
+    test([1], null, "[1] != []");
+    test("s", null, `"s" != ""`);
+    test(['c'], null, `"c" != ""`);
+    test!"!="(null, null, "`null` == `null`");
+}
+
 void main()
 {
     testIntegers();
@@ -130,5 +141,6 @@ void main()
     testStruct();
     testAA();
     testAttributes();
+    testVoidArray();
     fprintf(stderr, "success.\n");
 }