[clang][p2719] Module deserialization does not restore allocator flags (#137102)

When serializing and deserializing a FunctionDecl we don't recover
whether or not the decl was a type aware allocator or destroying delete,
because in the final PR that information was placed in a side table in
ASTContext.

In principle it should be possible to re-do the semantic checks to
determine what these flags should be when deserializing, but it seems
like the most robust path is simply recording the flags directly in the
serialized AST.

Author: ojhunt

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -1076,6 +1076,8 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   FD->setFriendConstraintRefersToEnclosingTemplate(
       FunctionDeclBits.getNextBit());
   FD->setUsesSEHTry(FunctionDeclBits.getNextBit());
+  FD->setIsDestroyingOperatorDelete(FunctionDeclBits.getNextBit());
+  FD->setIsTypeAwareOperatorNewOrDelete(FunctionDeclBits.getNextBit());
 
   FD->EndRangeLoc = readSourceLocation();
   if (FD->isExplicitlyDefaulted())

clang/lib/Serialization/ASTWriterDecl.cpp

@@ -847,6 +847,8 @@ void ASTDeclWriter::VisitFunctionDecl(FunctionDecl *D) {
   FunctionDeclBits.addBit(D->isInstantiatedFromMemberTemplate());
   FunctionDeclBits.addBit(D->FriendConstraintRefersToEnclosingTemplate());
   FunctionDeclBits.addBit(D->usesSEHTry());
+  FunctionDeclBits.addBit(D->isDestroyingOperatorDelete());
+  FunctionDeclBits.addBit(D->isTypeAwareOperatorNewOrDelete());
   Record.push_back(FunctionDeclBits);
 
   Record.AddSourceLocation(D->getEndLoc());

clang/test/Modules/Inputs/PR137102/module.modulemap

@@ -0,0 +1 @@
+module type_aware_destroying_new_delete { header "type_aware_destroying_new_delete.h" export * }

clang/test/Modules/Inputs/PR137102/type_aware_destroying_new_delete.h

@@ -0,0 +1,52 @@
+
+namespace std {
+    struct destroying_delete_t { };
+    template <class T> struct type_identity {
+        using type = T;
+    };
+    typedef __SIZE_TYPE__ size_t;
+    enum class align_val_t : size_t;
+};
+
+struct A {
+    A();
+   void *operator new(std::size_t);
+   void operator delete(A*, std::destroying_delete_t);
+};
+
+struct B {
+    B();
+    void *operator new(std::type_identity<B>, std::size_t, std::align_val_t);
+    void operator delete(std::type_identity<B>, void*, std::size_t, std::align_val_t);
+};
+
+struct C {
+    C();
+    template <class T> void *operator new(std::type_identity<T>, std::size_t, std::align_val_t);
+    template <class T> void operator delete(std::type_identity<T>, void*, std::size_t, std::align_val_t);
+};
+
+struct D {
+    D();
+};
+void *operator new(std::type_identity<D>, std::size_t, std::align_val_t);
+void operator delete(std::type_identity<D>, void*, std::size_t, std::align_val_t);
+
+struct E {
+    E();
+};
+template <class T> void *operator new(std::type_identity<T>, std::size_t, std::align_val_t);
+template <class T> void operator delete(std::type_identity<T>, void*, std::size_t, std::align_val_t);
+
+void in_module_tests() {
+  A* a = new A;
+  delete a;
+  B *b = new B;
+  delete b;
+  C *c = new C;
+  delete c;
+  D *d = new D;
+  delete d;
+  E *e = new E;
+  delete e;
+}

clang/test/Modules/type-aware-destroying-new-and-delete-modules.cpp

@@ -0,0 +1,23 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -x c++ -std=c++26 -fmodules-cache-path=%t -I %S/Inputs/PR137102 -emit-llvm-only %s
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -x c++ -std=c++26 -fmodules-cache-path=%t -I %S/Inputs/PR137102 -emit-llvm-only %s -triple i686-windows
+
+#include "type_aware_destroying_new_delete.h"
+
+
+static void call_in_module_function(void) {
+    in_module_tests();
+}
+
+void out_of_module_tests() {
+    A* a = new A;
+    delete a;
+    B *b = new B;
+    delete b;
+    C *c = new C;
+    delete c;
+    D *d = new D;
+    delete d;
+    E *e = new E;
+    delete e;
+}

clang/test/PCH/Inputs/type_aware_destroying_new_delete.h

@@ -0,0 +1,52 @@
+
+namespace std {
+    struct destroying_delete_t { };
+    template <class T> struct type_identity {
+        using type = T;
+    };
+    typedef __SIZE_TYPE__ size_t;
+    enum class align_val_t : size_t;
+};
+
+struct A {
+    A();
+   void *operator new(std::size_t);
+   void operator delete(A*, std::destroying_delete_t);
+};
+
+struct B {
+    B();
+    void *operator new(std::type_identity<B>, std::size_t, std::align_val_t);
+    void operator delete(std::type_identity<B>, void*, std::size_t, std::align_val_t);
+};
+
+struct C {
+    C();
+    template <class T> void *operator new(std::type_identity<T>, std::size_t, std::align_val_t);
+    template <class T> void operator delete(std::type_identity<T>, void*, std::size_t, std::align_val_t);
+};
+
+struct D {
+    D();
+};
+void *operator new(std::type_identity<D>, std::size_t, std::align_val_t);
+void operator delete(std::type_identity<D>, void*, std::size_t, std::align_val_t);
+
+struct E {
+    E();
+};
+template <class T> void *operator new(std::type_identity<T>, std::size_t, std::align_val_t);
+template <class T> void operator delete(std::type_identity<T>, void*, std::size_t, std::align_val_t);
+
+void in_pch_tests() {
+  A* a = new A;
+  delete a;
+  B *b = new B;
+  delete b;
+  C *c = new C;
+  delete c;
+  D *d = new D;
+  delete d;
+  E *e = new E;
+  delete e;
+}

clang/test/PCH/type-aware-destroying-new-and-delete-pch.cpp

@@ -0,0 +1,27 @@
+// Test this without pch.
+// RUN: %clang_cc1 -x c++ -std=c++26 -include %S/Inputs/type_aware_destroying_new_delete.h -emit-llvm -o - %s
+
+// Test with pch.
+// RUN: %clang_cc1 -x c++ -std=c++26 -emit-pch -o %t %S/Inputs/type_aware_destroying_new_delete.h
+// RUN: %clang_cc1 -x c++ -std=c++26 -include-pch %t -emit-llvm -o - %s 
+
+// RUN: %clang_cc1 -x c++ -std=c++11 -emit-pch -fpch-instantiate-templates -o %t %S/Inputs/type_aware_destroying_new_delete.h
+// RUN: %clang_cc1 -x c++ -std=c++11 -include-pch %t -emit-llvm -o - %s
+
+
+static void call_in_pch_function(void) {
+    in_pch_tests();
+}
+
+void out_of_pch_tests() {
+    A* a = new A;
+    delete a;
+    B *b = new B;
+    delete b;
+    C *c = new C;
+    delete c;
+    D *d = new D;
+    delete d;
+    E *e = new E;
+    delete e;
+}