[llvm] r252537 - Fix -Wdeprecated warnings due to the use of copy ops on SCEVPredicate derived class objects

[Vasileios Kalintiris via llvm-commits]

The test-case compiles fine with & without the base struct: https://goo.gl/gChBXX

-Vasileios
________________________________
From: David Blaikie [dblaikie at gmail.com]
Sent: 12 November 2015 16:21
To: Vasileios Kalintiris
Cc: llvm-commits at lists.llvm.org
Subject: Re: [llvm] r252537 - Fix -Wdeprecated warnings due to the use of copy ops on SCEVPredicate derived class objects



On Thu, Nov 12, 2015 at 7:06 AM, Vasileios Kalintiris <Vasileios.Kalintiris at imgtec.com<mailto:Vasileios.Kalintiris at imgtec.com>> wrote:
Hi David,

This introduced a "class has virtual functions and accessible non-virtual destructor" warning that is being printed a lot of times (g++ 5.2.1). Can you look at this?

We should disable that warning on GCC. This API seems safe to me, no? The base class's dtor is protected (so external users can't polymorphically delete objects) and the derived classes have public non-virtual dtors, but are final (so no further classes can derived from them)

This is not the only API that uses that pattern - oh, maybe it's the FoldingSetNode that's complicating this? Could you check if this produces the warning on GCC (is there a pastebin that runs that version of GCC so I can check this myself easily?)

struct base {
};

struct middle: base {
  virtual void func();
protected:
  ~middle() = default;
};

struct derived final : middle {
};

& then if you remove the base class, does the warning go away?

- Dave


Thanks,
Vasileios

[8/101] /usr/local/bin/g++   -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Ilib/Transforms/Utils -I/home/vk/repos/llvm/lib/Transforms/Utils -Iinclude -I/home/vk/r
epos/llvm/include -fPIC -fvisibility-inlines-hidden -Wall -W -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wno-maybe-uninitialized -Wnon-virtual-dtor -Wno-comment -std
=c++11 -g -fPIC   -gsplit-dwarf  -fno-exceptions -fno-rtti -MMD -MT lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyIndVar.cpp.o -MF lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyIndVar.cpp.o.d -o
lib/Transforms/Utils/CMakeFiles/LLVMTransformUtils.dir/SimplifyIndVar.cpp.o -c /home/vk/repos/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
In file included from /home/vk/repos/llvm/include/llvm/Analysis/ScalarEvolutionExpressions.h:19:0,
                 from /home/vk/repos/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp:22:
/home/vk/repos/llvm/include/llvm/Analysis/ScalarEvolution.h:174:9: warning: ‘class llvm::SCEVPredicate’ has virtual functions and accessible non-virtual destructor [-Wnon-virtual-dtor]
   class SCEVPredicate : public FoldingSetNode {
         ^
/home/vk/repos/llvm/include/llvm/Analysis/ScalarEvolution.h:244:9: warning: base class ‘class llvm::SCEVPredicate’ has accessible non-virtual destructor [-Wnon-virtual-dtor]
   class SCEVEqualPredicate final : public SCEVPredicate {
         ^
/home/vk/repos/llvm/include/llvm/Analysis/ScalarEvolution.h:275:9: warning: base class ‘class llvm::SCEVPredicate’ has accessible non-virtual destructor [-Wnon-virtual-dtor]
   class SCEVUnionPredicate final : public SCEVPredicate {
         ^

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