Merge pull request #3582 from teodutu/fix-_d_arrayctor

Fix _d_arrayctor to allow @nogc

Author: RazvanN7

src/core/internal/array/construction.d

@@ -27,24 +27,21 @@ Tarr _d_arrayctor(Tarr : T[], T)(return scope Tarr to, scope Tarr from) @trusted
     import core.internal.traits : hasElaborateCopyConstructor, Unqual;
     import core.lifetime : copyEmplace;
     import core.stdc.string : memcpy;
+    import core.stdc.stdint : uintptr_t;
     debug(PRINTF) import core.stdc.stdio;
 
-    // Force `enforceRawArraysConformable` to be `pure`
-    void enforceRawArraysConformable(const char[] action, const size_t elementSize, const void[] a1, const void[] a2, in bool allowOverlap = false) @trusted
-    {
-        import core.internal.util.array : enforceRawArraysConformable;
-
-        alias Type = void function(const char[] action, const size_t elementSize, const void[] a1, const void[] a2, in bool allowOverlap = false) pure nothrow;
-        (cast(Type)&enforceRawArraysConformable)(action, elementSize, a1, a2, allowOverlap);
-    }
-
     debug(PRINTF) printf("_d_arrayctor(to = %p,%d, from = %p,%d) size = %d\n", from.ptr, from.length, to.ptr, to.length, T.tsize);
 
-    auto element_size = T.sizeof;
-
+    // Rewrite `enforceRawArraysConformable` manually to allow @nogc.
+    // Use more austere errors because @nogc doesn't allow string concatenation.
     void[] vFrom = (cast(void*)from.ptr)[0..from.length];
     void[] vTo = (cast(void*)to.ptr)[0..to.length];
-    enforceRawArraysConformable("initialization", element_size, vFrom, vTo, false);
+    assert(vFrom.length == vTo.length, "Array lengths don't match");
+
+    const ptrTo = cast(uintptr_t)vTo.ptr;
+    const ptrFrom = cast(uintptr_t)vFrom.ptr;
+    const d = ptrTo > ptrFrom ? ptrTo - ptrFrom : ptrFrom - ptrTo;
+    assert(d >= vFrom.length * T.sizeof, "Overlapping arrays");
 
     static if (hasElaborateCopyConstructor!T)
     {