P0035R4: Semantic analysis and code generation for C++17 overaligned

allocation.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@283722 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 4 deletions

diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index d7472fcc35..97f75a0205 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -1577,17 +1577,35 @@ bool CXXMethodDecl::isUsualDeallocationFunction() const {
   //   deallocation function. [...]
   if (getNumParams() == 1)
     return true;
+  unsigned UsualParams = 1;
 
-  // C++ [basic.stc.dynamic.deallocation]p2:
+  // C++ <=14 [basic.stc.dynamic.deallocation]p2:
   //   [...] If class T does not declare such an operator delete but does 
   //   declare a member deallocation function named operator delete with 
   //   exactly two parameters, the second of which has type std::size_t (18.1),
   //   then this function is a usual deallocation function.
+  //
+  // C++17 says a usual deallocation function is one with the signature
+  //   (void* [, size_t] [, std::align_val_t] [, ...])
+  // and all such functions are usual deallocation functions. It's not clear
+  // that allowing varargs functions was intentional.
   ASTContext &Context = getASTContext();
-  if (getNumParams() != 2 ||
-      !Context.hasSameUnqualifiedType(getParamDecl(1)->getType(),
-                                      Context.getSizeType()))
+  if (UsualParams < getNumParams() &&
+      Context.hasSameUnqualifiedType(getParamDecl(UsualParams)->getType(),
+                                     Context.getSizeType()))
+    ++UsualParams;
+
+  if (UsualParams < getNumParams() &&
+      getParamDecl(UsualParams)->getType()->isAlignValT())
+    ++UsualParams;
+
+  if (UsualParams != getNumParams())
     return false;
+
+  // In C++17 onwards, all potential usual deallocation functions are actual
+  // usual deallocation functions.
+  if (Context.getLangOpts().AlignedAllocation)
+    return true;
                  
   // This function is a usual deallocation function if there are no 
   // single-parameter deallocation functions of the same kind.