diff --git a/compiler/src/dmd/clone.d b/compiler/src/dmd/clone.d
index 971e8020d1..d7658c68ec 100644
--- a/compiler/src/dmd/clone.d
+++ b/compiler/src/dmd/clone.d
@@ -269,7 +269,7 @@ FuncDeclaration buildOpAssign(StructDeclaration sd, Scope* sc)
         return null;
 
     //printf("StructDeclaration::buildOpAssign() %s\n", sd.toChars());
-    StorageClass stc = STC.safe | STC.nothrow_ | STC.pure_ | STC.nogc;
+    StorageClass stc = STC.safe;
     Loc declLoc = sd.loc;
     Loc loc; // internal code should have no loc to prevent coverage
 
@@ -1278,7 +1278,7 @@ FuncDeclaration buildPostBlit(StructDeclaration sd, Scope* sc)
     const hasUserDefinedPosblit = sd.postblits.length && !sd.postblits[0].isDisabled ? true : false;
 
     // by default, the storage class of the created postblit
-    StorageClass stc = STC.safe | STC.nothrow_ | STC.pure_ | STC.nogc;
+    StorageClass stc = STC.safe;
     Loc declLoc = sd.postblits.length ? sd.postblits[0].loc : sd.loc;
     Loc loc; // internal code should have no loc to prevent coverage
 
@@ -1380,6 +1380,7 @@ FuncDeclaration buildPostBlit(StructDeclaration sd, Scope* sc)
         // perform semantic on the member postblit in order to
         // be able to aggregate it later on with the rest of the
         // postblits
+        sdv.postblit.isGenerated = true;
         functionSemantic(sdv.postblit);
 
         stc = mergeFuncAttrs(stc, sdv.postblit);
@@ -1445,6 +1446,7 @@ FuncDeclaration buildPostBlit(StructDeclaration sd, Scope* sc)
          */
         if (sdv.dtor)
         {
+            sdv.dtor.isGenerated = true;
             functionSemantic(sdv.dtor);
 
             // keep a list of fields that need to be destroyed in case
diff --git a/compiler/test/compilable/cppmangle.d b/compiler/test/compilable/cppmangle.d
index 4b9046e811..c6c921d7b0 100644
--- a/compiler/test/compilable/cppmangle.d
+++ b/compiler/test/compilable/cppmangle.d
@@ -666,6 +666,8 @@ extern (C++) class C18890_2
     Agg s;
 }
 
+void test18890()
+{
 version (CppMangle_Itanium)
 {
     static assert(C18890.__dtor.mangleof == "_ZN6C18890D1Ev");
@@ -690,6 +692,7 @@ version (CppMangle_MSVC)
         static assert(C18890_2.__xdtor.mangleof == "??_GC18890_2@@UEAAPEAXI@Z");
     }
 }
+}
 
 /**************************************/
 // https://issues.dlang.org/show_bug.cgi?id=18891
@@ -704,6 +707,8 @@ extern (C++) class C18891
     Agg s;
 }
 
+void test18891()
+{
 version (CppMangle_Itanium)
 {
     static assert(C18891.__dtor.mangleof == "_ZN6C18891D1Ev");
@@ -722,6 +727,7 @@ version (CppMangle_MSVC)
         static assert(C18891.__xdtor.mangleof == "??_GC18891@@UEAAPEAXI@Z");
     }
 }
+}
 
 /**************************************/
 // Test C++ operator mangling
diff --git a/compiler/test/compilable/testInference.d b/compiler/test/compilable/testInference.d
index bddbaf4294..5091b99896 100644
--- a/compiler/test/compilable/testInference.d
+++ b/compiler/test/compilable/testInference.d
@@ -817,4 +817,22 @@ void test13840() nothrow
     {}
 }
 
-// Add more tests regarding inferences later.
+/***************************************************/
+// https://github.com/dlang/dmd/pull/20685
+
+struct T1
+{
+    int a;
+    inout this(ref inout T1 t) @nogc nothrow pure { a = t.a; }
+}
+
+struct S1
+{
+    T1 t; // generate copy constructor, infer @nogc nothrow pure
+}
+
+void test1() @nogc nothrow pure
+{
+    S1 s;
+    S1 t = s;
+}