Merge pull request #11881 from WalterBright/fix21324

fix Issue 21324 - @LiVe not detecting overwrite of Owner without disp…

Author: dkorpel

src/dmd/ob.d

@@ -1977,7 +1977,12 @@ void checkObErrors(ref ObState obstate)
             else if (isReadonlyPtr(v))
                 pvs.state = PtrState.Readonly;
             else
+            {
+                if (pvs.state == PtrState.Owner && v.type.hasPointersToMutableFields())
+                    v.error(e.loc, "assigning to Owner without disposing of owned value");
+
                 pvs.state = PtrState.Owner;
+            }
             pvs.deps.zero();
 
             EscapeByResults er;

test/fail_compilation/fob1.d

@@ -17,6 +17,7 @@ fail_compilation/fob1.d(104): Error: variable `fob1.foo1.p` is returned but is U
 
 /* TEST_OUTPUT:
 ---
+fail_compilation/fob1.d(204): Error: variable `fob1.foo2.p` assigning to Owner without disposing of owned value
 fail_compilation/fob1.d(203): Error: variable `fob1.foo2.p` is left dangling at return
 ---
 */

test/fail_compilation/fob2.d

@@ -175,3 +175,21 @@ void free7(int*);
 {
     free7(p);
 }
+
+/* TEST_OUTPUT:
+---
+fail_compilation/fob2.d(807): Error: variable `fob2.test8.p` assigning to Owner without disposing of owned value
+---
+*/
+
+#line 800
+
+int* malloc8();
+void free8(int*);
+
+@live void test8()
+{
+    int* p = malloc8();
+    p = malloc8();  // error here
+    free8(p);
+}