[PATCH] D141023: [C++20] [Modules] Make placement allocation functions always acceptable

[Chuanqi Xu via Phabricator via cfe-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGee1be282241b: [C++20] [Modules] Make placement allocation functions always visible (authored by ChuanqiXu).
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D141023/new/

https://reviews.llvm.org/D141023

Files:
  clang/lib/Sema/SemaLookup.cpp
  clang/test/Modules/placement-new-reachable.cpp


Index: clang/test/Modules/placement-new-reachable.cpp
===================================================================
--- /dev/null
+++ clang/test/Modules/placement-new-reachable.cpp
@@ -0,0 +1,39 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/A.cppm -emit-module-interface -o %t/A.pcm
+// RUN: %clang_cc1 -std=c++20 %t/Use.cpp -fprebuilt-module-path=%t -fsyntax-only -verify
+
+//--- placement.h
+namespace std {
+  using size_t = decltype(sizeof(0));
+}
+void *operator new(std::size_t, void *p) { return p; }
+
+//--- A.cppm
+module;
+#include "placement.h"
+export module A;
+export template<class T>
+struct A {
+    A(void *p) : ptr(new (p) T(43)) {}
+private:
+    void *ptr;
+};
+
+export struct B {
+    B(void *p) : ptr(new (p) int(43)) {}
+private:
+    void *ptr;
+};
+
+//--- Use.cpp
+// expected-no-diagnostics
+import A;
+void bar(int *);
+void foo(void *ptr) {
+    A<int>(nullptr); // Good. It should be OK to construct A.
+    void *p = ::operator new(sizeof(int), ptr); // Bad. The function shouldn't be visible here.
+    void *q = new (ptr) int(43); // Good. We don't call the placement allocation function directly.
+}
Index: clang/lib/Sema/SemaLookup.cpp
===================================================================
--- clang/lib/Sema/SemaLookup.cpp
+++ clang/lib/Sema/SemaLookup.cpp
@@ -2099,6 +2099,22 @@
   if (auto *DeductionGuide = ND->getDeclName().getCXXDeductionGuideTemplate())
     return SemaRef.hasReachableDefinition(DeductionGuide);
 
+  // FIXME: The lookup for allocation function is a standalone process.
+  // (We can find the logics in Sema::FindAllocationFunctions)
+  //
+  // Such structure makes it a problem when we instantiate a template
+  // declaration using placement allocation function if the placement
+  // allocation function is invisible.
+  // (See https://github.com/llvm/llvm-project/issues/59601)
+  //
+  // Here we workaround it by making the placement allocation functions
+  // always acceptable. The downside is that we can't diagnose the direct
+  // use of the invisible placement allocation functions. (Although such uses
+  // should be rare).
+  if (auto *FD = dyn_cast<FunctionDecl>(ND);
+      FD && FD->isReservedGlobalPlacementOperator())
+    return true;
+
   auto *DC = ND->getDeclContext();
   // If ND is not visible and it is at namespace scope, it shouldn't be found
   // by name lookup.


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D141023.487259.patch
Type: text/x-patch
Size: 2443 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20230109/4dd30ca6/attachment-0001.bin>