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

[David Blaikie via llvm-commits]

On Thu, Nov 12, 2015 at 7:06 AM, Vasileios Kalintiris <
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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