Fix Bugzilla 15315 - can break immutable with std.algorithm.move (#9032)

dlang · Jul 28, 2024 · 9ffe71f · 9ffe71f
1 parent 7a14c89
commit 9ffe71f
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Showing 2 changed files with 36 additions and 10 deletions.
diff --git a/std/algorithm/mutation.d b/std/algorithm/mutation.d
@@ -1071,10 +1071,20 @@ Params:
         copy is performed.
 */
 void move(T)(ref T source, ref T target)
+if (__traits(compiles, target = T.init))
 {
     moveImpl(target, source);
 }
 
+/// ditto
+template move(T)
+if (!__traits(compiles, imported!"std.traits".lvalueOf!T = T.init))
+{
+    ///
+    deprecated("Can't move into `target` as `" ~ T.stringof ~ "` can't be assigned")
+    void move(ref T source, ref T target) => moveImpl(target, source);
+}
+
 /// For non-struct types, `move` just performs `target = source`:
 @safe unittest
 {
@@ -1184,6 +1194,19 @@ pure nothrow @safe @nogc unittest
     assert(s53 is s51);
 }
 
+@system unittest
+{
+    static struct S
+    {
+        immutable int i;
+        ~this() @safe {}
+    }
+    alias ol = __traits(getOverloads, std.algorithm.mutation, "move", true)[1];
+    static assert(__traits(isDeprecated, ol!S));
+    // uncomment after deprecation
+    //static assert(!__traits(compiles, { S a, b; move(a, b); }));
+}
+
 /// Ditto
 T move(T)(return scope ref T source)
 {

diff --git a/std/typecons.d b/std/typecons.d
@@ -10928,19 +10928,22 @@ struct RefCounted(T, RefCountedAutoInitialize autoInit =
         swap(_refCounted._store, rhs._refCounted._store);
     }
 
-    void opAssign(T rhs)
+    static if (__traits(compiles, lvalueOf!T = T.init))
     {
-        import std.algorithm.mutation : move;
-
-        static if (autoInit == RefCountedAutoInitialize.yes)
-        {
-            _refCounted.ensureInitialized();
-        }
-        else
+        void opAssign(T rhs)
         {
-            assert(_refCounted.isInitialized);
+            import std.algorithm.mutation : move;
+
+            static if (autoInit == RefCountedAutoInitialize.yes)
+            {
+                _refCounted.ensureInitialized();
+            }
+            else
+            {
+                assert(_refCounted.isInitialized);
+            }
+            move(rhs, _refCounted._store._payload);
         }
-        move(rhs, _refCounted._store._payload);
     }
 
     static if (autoInit == RefCountedAutoInitialize.yes)