[cfe-dev] [llvm-dev] New warnings when building trunk with GCC 9

[Stephan Bergmann via cfe-dev]

On 13/09/2018 18:22, David Blaikie via llvm-dev wrote:
> On Thu, Sep 13, 2018 at 12:13 AM Dávid Bolvanský via llvm-dev 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>     /home/davidbolvansky/trunk/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp:79:40: 
>       required from here
>     /home/davidbolvansky/trunk/llvm/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h:314:29:
>     warning: redundant move in return statement [-Wredundant-move]
>     314 |         return std::move(Err);

Note that the move (into the implicit JITSymbol(Error) ctor) is only 
redundant if the compiler implements a fix for 
<http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1579> 
"Return by converting move constructor".  (But not sure whether the LLVM 
compiler baselines imply that, anyway.  In LibreOffice it forced me to 
introduce ugly #ifs, to not have to disable that warning outright, 
<https://cgit.freedesktop.org/libreoffice/core/commit/?id=dc06c8f4989fc28d0c31ebd333e53dfe0e0f5f66> 
"-Werror=redundant-move (GCC 9), take two".)