diff --git a/spec/legacy.dd b/spec/legacy.dd
index 89b7670d63..138ee672bc 100644
--- a/spec/legacy.dd
+++ b/spec/legacy.dd
@@ -24,6 +24,8 @@ $(COMMENT
         $(TROW Escaping $(DDSUBLINK spec/attribute, scope, `scope`) data,
             `scope` is $(LINK2 https://github.com/dlang/DIPs/blob/master/DIPs/other/DIP1000.md,
             enforced) in `@safe` code, 2024)
+        $(TROW $(RELATIVE_LINK2 struct-assign, Assigning to struct rvalue),
+            Disallow for structs which overload e.g. `opAssign`, 2024)
 
         $(COMMENT Not enforced yet)
         $(TROW `alias` target first syntax, use `alias name = target` instead.)
@@ -93,6 +95,41 @@ struct Foo
 }
 ---
 
+$(H2 $(LNAME2 struct-assign, Assigning to struct rvalue))
+
+    $(P It has always been an error for $(DDSUBLINK spec/struct, POD, POD) structs
+        to assign from an rvalue.)
+
+    $(P From the 2024 edition, it is an error to discard the result of an
+        assignment from a struct rvalue when it would call `opAssign`, `opOpAssign`,
+        `opUnary!"++"`, or `opUnary!"--"` and the struct has no pointer
+        fields:)
+
+---
+struct S
+{
+    int i;
+
+    void opAssign(S s);
+}
+
+S foo();
+
+void main()
+{
+    foo() = S(2); // Error, possible no-op
+}
+---
+    $(P Above, unless `opAssign` mutates global data, the assignment in `main`
+    will have no effect and indicates a bug.)
+
+$(H3 Corrective Action)
+
+    $(P If a struct rvalue assignment is needed to mutate global state, either
+    call the operator overload method directly or use an lvalue.
+    Note: Calling a non-const method on a struct rvalue
+    $(DDSUBLINK spec/struct, member-functions, is allowed).)
+
 
 $(SPEC_SUBNAV_PREV_NEXT glossary, Glossary, editions, Editions)
 )