[Sema] Issue diagnostics if a new/delete expression generates a call to

a c++17 aligned allocation/deallocation function that is unavailable in
the standard library on Apple platforms.

The aligned functions are implemented only in the following versions or
later versions of the OSes, so clang issues diagnostics if the deployment
target being targeted is older than these:

macosx: 10.13
ios: 11.0
tvos: 11.0
watchos: 4.0

The diagnostics are issued whenever the aligned functions are selected
except when the selected function has a definition in the same file.
If there is a user-defined function available somewhere else, option
-Wno-aligned-allocation-unavailable can be used to silence the
diagnostics.

rdar://problem/32664169

Differential Revision: https://reviews.llvm.org/D34574

llvm-svn: 306722

1 files changed, 26 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 71c4c8070e7..a9cf3ec7990 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -1646,6 +1646,27 @@ static bool isLegalArrayNewInitializer(CXXNewExpr::InitializationStyle Style,
   return false;
 }
 
+// Emit a diagnostic if an aligned allocation/deallocation function that is not
+// implemented in the standard library is selected.
+static void diagnoseUnavailableAlignedAllocation(const FunctionDecl &FD,
+                                                 SourceLocation Loc, bool IsDelete,
+                                                 Sema &S) {
+  if (!S.getLangOpts().AlignedAllocationUnavailable)
+    return;
+
+  // Return if there is a definition.
+  if (FD.isDefined())
+    return;
+
+  bool IsAligned = false;
+  if (FD.isReplaceableGlobalAllocationFunction(&IsAligned) && IsAligned) {
+    S.Diag(Loc, diag::warn_aligned_allocation_unavailable)
+         << IsDelete << FD.getType().getAsString()
+         << S.getASTContext().getTargetInfo().getTriple().str();
+    S.Diag(Loc, diag::note_silence_unligned_allocation_unavailable);
+  }
+}
+
 ExprResult
 Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
                   SourceLocation PlacementLParen,
@@ -2023,11 +2044,13 @@ Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
     if (DiagnoseUseOfDecl(OperatorNew, StartLoc))
       return ExprError();
     MarkFunctionReferenced(StartLoc, OperatorNew);
+    diagnoseUnavailableAlignedAllocation(*OperatorNew, StartLoc, false, *this);
   }
   if (OperatorDelete) {
     if (DiagnoseUseOfDecl(OperatorDelete, StartLoc))
       return ExprError();
     MarkFunctionReferenced(StartLoc, OperatorDelete);
+    diagnoseUnavailableAlignedAllocation(*OperatorDelete, StartLoc, true, *this);
   }
 
   // C++0x [expr.new]p17:
@@ -3243,6 +3266,9 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
                       PDiag(diag::err_access_dtor) << PointeeElem);
       }
     }
+
+    diagnoseUnavailableAlignedAllocation(*OperatorDelete, StartLoc, true,
+                                         *this);
   }
 
   CXXDeleteExpr *Result = new (Context) CXXDeleteExpr(