llvm dev - Jan 2017 - Upcoming removal of std::auto_ptr (in C++1z)

The upcoming C++1z (probably C++17) standard will not contain several
things - most notably auto_ptr.

Soon, libc++ will not be providing auto_ptr by default when building in
C++1z mode.
You'll be able to get it back with a
"-D_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" on your command line, or
"#define
_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" before including any libc++ header
files.

Grepping through the LLVM code base, I found several references to auto_ptr
that should be investigated.  Most, if not all of them are in test cases.

# Tests that reference auto_ptr
llvm/test/CodeGen/X86/negate-add-zero.ll
llvm/test/Transforms/DeadStoreElimination/2011-09-06-EndOfFunction.ll
llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll

# Things that define their own auto_ptr
llvm/tools/clang/test/Analysis/diagnostics/Inputs/include/report-issues-within-main-file.h
llvm/tools/clang/test/Analysis/diagnostics/report-issues-within-main-file.cpp
llvm/tools/clang/test/CodeGenCXX/2010-07-23-DeclLoc.cpp

# clang-tidy bits that reference auto_ptr
llvm/tools/clang/tools/extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
llvm/tools/clang/tools/extra/clang-tidy/modernize/ReplaceAutoPtrCheck.h
llvm/tools/clang/tools/extra/docs/clang-tidy/checks/modernize-use-emplace.rst
llvm/tools/clang/tools/extra/include-fixer/find-all-symbols/STLPostfixHeaderMap.cpp
llvm/tools/clang/tools/extra/test/clang-tidy/Inputs/modernize-replace-auto-ptr/memory.h
llvm/tools/clang/tools/extra/test/clang-tidy/modernize-replace-auto-ptr.cpp
llvm/tools/clang/www/analyzer/potential_checkers.html


The first three files should be investigated.
I believe that the second group should not be affected by this change.
The third group (the clang-tidy changes) probably will not be affected.

-- Marshall
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Thanks Marshall,

Regarding the first group - these are all LLVM IR-level optimizer tests, so
they don't actually care about what a particular version of C++ does or
does not contain.

Thanks,
  Michael

On Mon, Jan 23, 2017 at 1:32 PM, Marshall Clow via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> The upcoming C++1z (probably C++17) standard will not contain several
> things - most notably auto_ptr.
>
> Soon, libc++ will not be providing auto_ptr by default when building in
> C++1z mode.
> You'll be able to get it back with a
> "-D_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" on your command line,
or
> "#define _LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" before including
any
> libc++ header files.
>
> Grepping through the LLVM code base, I found several references to
> auto_ptr that should be investigated.  Most, if not all of them are in test
> cases.
>
> # Tests that reference auto_ptr
> llvm/test/CodeGen/X86/negate-add-zero.ll
> llvm/test/Transforms/DeadStoreElimination/2011-09-06-EndOfFunction.ll
> llvm/test/Transforms/MemCpyOpt/loadstore-sret.ll
>
> # Things that define their own auto_ptr
> llvm/tools/clang/test/Analysis/diagnostics/Inputs/
> include/report-issues-within-main-file.h
> llvm/tools/clang/test/Analysis/diagnostics/report-
> issues-within-main-file.cpp
> llvm/tools/clang/test/CodeGenCXX/2010-07-23-DeclLoc.cpp
>
> # clang-tidy bits that reference auto_ptr
> llvm/tools/clang/tools/extra/clang-tidy/modernize/ReplaceAutoPtrCheck.cpp
> llvm/tools/clang/tools/extra/clang-tidy/modernize/ReplaceAutoPtrCheck.h
> llvm/tools/clang/tools/extra/docs/clang-tidy/checks/
> modernize-use-emplace.rst
> llvm/tools/clang/tools/extra/include-fixer/find-all-
> symbols/STLPostfixHeaderMap.cpp
> llvm/tools/clang/tools/extra/test/clang-tidy/Inputs/
> modernize-replace-auto-ptr/memory.h
> llvm/tools/clang/tools/extra/test/clang-tidy/modernize-
> replace-auto-ptr.cpp
> llvm/tools/clang/www/analyzer/potential_checkers.html
>
>
> The first three files should be investigated.
> I believe that the second group should not be affected by this change.
> The third group (the clang-tidy changes) probably will not be affected.
>
> -- Marshall
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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> On Jan 23, 2017, at 15:32, Marshall Clow via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> The upcoming C++1z (probably C++17) standard will not contain several
things - most notably auto_ptr.
Purely for my own edification, is the rationale for this available somewhere?

Thank you,

Steve

-- 
Stephen Checkoway

On 24-01-17 02:34, Stephen Checkoway via llvm-dev wrote:
>> On Jan 23, 2017, at 15:32, Marshall Clow via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>>
>> The upcoming C++1z (probably C++17) standard will not contain several
things - most notably auto_ptr.
> Purely for my own edification, is the rationale for this available
somewhere?
According to [1] it has been deprecated since C++11 and using unique_ptr 
should be prefered.

Cheers,
  Roel

[1] http://www.cplusplus.com/reference/memory/auto_ptr/

On Mon, Jan 23, 2017 at 6:34 PM, Stephen Checkoway via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
>
> > On Jan 23, 2017, at 15:32, Marshall Clow via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > The upcoming C++1z (probably C++17) standard will not contain several
> things - most notably auto_ptr.
>
> Purely for my own edification, is the rationale for this available
> somewhere?
>
Here is a draft of the paper <https://isocpp.org/files/papers/N4190.txt>
which removed it.

The short and sweet rational for it is that auto_ptr was designed before
C++ had move semantics.
and because of that it doesn't behave like a move-only type should and is
unsafe because of it.

>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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On Mon, Jan 23, 2017 at 1:32 PM, Marshall Clow <mclow.lists at gmail.com>
wrote:
> The upcoming C++1z (probably C++17) standard will not contain several
> things - most notably auto_ptr.
>
> Soon, libc++ will not be providing auto_ptr by default when building in
> C++1z mode.
> You'll be able to get it back with a
> "-D_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" on your command line,
or
> "#define _LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" before including
any
> libc++ header files.
>
>
Landed as revision 292986.

-- Marshall
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