DR1872: don't allow any calls to virtual functions in constant

evaluation.

Not even in cases where we would not actually perform virtual dispatch.

llvm-svn: 360370

1 files changed, 8 insertions, 6 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 11e753c0771..3581d97c8b1 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4381,6 +4381,14 @@ static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
     return false;
   }
 
+  // DR1872: An instantiated virtual constexpr function can't be called in a
+  // constant expression.
+  if (isa<CXXMethodDecl>(Declaration) &&
+      cast<CXXMethodDecl>(Declaration)->isVirtual()) {
+    Info.FFDiag(CallLoc, diag::note_constexpr_virtual_call);
+    return false;
+  }
+
   // Can we evaluate this function call?
   if (Definition && Definition->isConstexpr() &&
       !Definition->isInvalidDecl() && Body)
@@ -4999,12 +5007,6 @@ public:
     if (This && !This->checkSubobject(Info, E, CSK_This))
       return false;
 
-    // DR1358 allows virtual constexpr functions in some cases. Don't allow
-    // calls to such functions in constant expressions.
-    if (This && !HasQualifier &&
-        isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual())
-      return Error(E, diag::note_constexpr_virtual_call);
-
     const FunctionDecl *Definition = nullptr;
     Stmt *Body = FD->getBody(Definition);