Don't speculatively emit VTTs for classes unless we are able to correctly emit references to all the functions they will (directly or indirectly) reference.
Summary:
This fixes a miscompile where we'd emit a VTT for a class that ends up
referencing an inline virtual member function that we can't actually
emit a body for (because we never instantiated it in the current TU),
which in a corner case of a corner case can lead to link errors.
Reviewers: rjmccall
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D54768
llvm-svn: 347692
diff --git a/clang/test/CodeGenCXX/speculative-vtt.cpp b/clang/test/CodeGenCXX/speculative-vtt.cpp
new file mode 100644
index 0000000..120d95d
--- /dev/null
+++ b/clang/test/CodeGenCXX/speculative-vtt.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu %s -O2 -disable-llvm-passes -emit-llvm -o - | FileCheck %s
+struct A { virtual ~A(); };
+template<typename T> struct B : virtual A {
+ ~B() override {}
+};
+struct C : B<int>, B<float> { C(); ~C() override; };
+struct D : C { ~D() override; };
+
+// We must not create a reference to B<int>::~B() here, because we're not going to emit it.
+// CHECK-NOT: @_ZN1BIiED1Ev
+// CHECK-NOT: @_ZTC1D0_1BIiE =
+// CHECK-NOT: @_ZTT1D = available_externally
+D *p = new D;