use make_shared

[pragmaticQt]

Pull Request Template

Description

C++ Core Guidelines
C.151: Use make_shared() to construct objects owned by shared_ptrs.

Fixes # (issue)

How Has This Been Tested?

GCC9.2.0.

• Test build and run.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[phillipjohnston]

Happy to make this change, but the build currently fails due to template parameter mismatch:

c++ -Iexamples/cpp/813c7e2@@shared_ptr@exe -Iexamples/cpp -I../examples/cpp -Xclang -fcolor-diagnostics -pipe -Wall -Winvalid-pch -Wnon-virtual-dtor -std=c++17 -g -Wno-unknown-pragmas -fno-rtti -fno-exceptions -fno-unwind-tables -MD -MQ 'examples/cpp/813c7e2@@shared_ptr@exe/shared_ptr.cpp.o' -MF 'examples/cpp/813c7e2@@shared_ptr@exe/shared_ptr.cpp.o.d' -o 'examples/cpp/813c7e2@@shared_ptr@exe/shared_ptr.cpp.o' -c ../examples/cpp/shared_ptr.cpp
../examples/cpp/shared_ptr.cpp:27:21: error: unknown type name 'Arg'
                        EnableMakeShared(Arg&&... arg) : SharedThing(std::forward<Arg>(arg)...) {}
                                         ^
../examples/cpp/shared_ptr.cpp:27:26: error: type 'int &&' of function parameter pack does not contain any unexpanded parameter packs
                        EnableMakeShared(Arg&&... arg) : SharedThing(std::forward<Arg>(arg)...) {}
                                         ~~~~~^~~~~~~
../examples/cpp/shared_ptr.cpp:27:62: error: use of undeclared identifier 'Arg'; did you mean 'arg'?
                        EnableMakeShared(Arg&&... arg) : SharedThing(std::forward<Arg>(arg)...) {}
                                                                                  ^~~
                                                                                  arg
../examples/cpp/shared_ptr.cpp:27:30: note: 'arg' declared here
                        EnableMakeShared(Arg&&... arg) : SharedThing(std::forward<Arg>(arg)...) {}
                                                  ^
../examples/cpp/shared_ptr.cpp:29:58: error: use of undeclared identifier 'Arg'
                return std::make_shared<EnableMakeShared>(std::forward<Arg>(arg)...);

[phillipjohnston]

Please add a comment above the struct explaining what its purpose is to the uninitiated.