Merge pull request #4736 from 9rnsr/fix14672

[REG2.067.0] Issue 14672 - Internal error: e2ir.c 4620 when copying array of derived class to an array of base class

src/e2ir.c

@@ -4654,7 +4654,12 @@ elem *toElem(Expression *e, IRState *irs)
             else
             {
                 assert(t1->ty == tb->ty);   // Tarray or Tsarray
-                assert(t1->nextOf()->equivalent(tb->nextOf()));
+
+                // Bugzilla 14672: If se is in left side operand of element-wise
+                // assignment, the element type can be painted to the base class.
+                int offset;
+                assert(t1->nextOf()->equivalent(tb->nextOf()) ||
+                       tb->nextOf()->isBaseOf(t1->nextOf(), &offset) && offset == 0);
             }
             el_setLoc(e, se->loc);
             result = e;

test/runnable/testassign.d

@@ -1094,6 +1094,41 @@ void test12500()
     ++foo *= 1.5;   // Rewrite to: (foo += 1) *= 1.5;
 }
 
+/***************************************************/
+// 14672
+
+void test14672()
+{
+    interface I {}
+
+    class B {}
+    class D : B, I {}
+
+    D d = new D();
+    D[] da = [d];
+    B[] ba = [null];
+    I[] ia = [null];
+
+    // ba and da points different payloads,
+    // so element-wise assignment should work.
+    ba[] = da[];    // OK <- e2ir ICE
+    assert(ba[0] is d);
+
+    // Today element-wise assignment is implemented as memcpy, For that reason
+    // the conversion from derived classes to base interfaces is disallowed
+    // because it requries offset adjustments.
+    static assert(!__traits(compiles, { ia[] = da[]; }));
+
+    // after the assignment, ba will wongly point the payload of da,
+    // that's typed as D[]. To aboid type system breaking, it's disallowed.
+    static assert(!__traits(compiles, { ba = da; }));
+
+    // the assigned array literal is a new payload,
+    // so rebinding ba should work.
+    ba = [d];       // OK
+    assert(ba[0] is d);
+}
+
 /***************************************************/
 
 int main()
@@ -1123,8 +1158,8 @@ int main()
     test12212();
     test12650();
     test13044();
-
     test12500();
+    test14672();
 
     printf("Success\n");
     return 0;