Adding CMakeLists.txt for cpp version

[micaah42]

Hello there,

I added a minimal CMakeLists.txt to make it easier to include this repository in cmake driven projects.

You can build a static library using:

cd cpp
mkdir build && cd build
cmake ..
make

Or include in other projects like this:

include(FetchContent)

FetchContent_Declare(qrcodegen
    SOURCE_SUBDIR cpp
    GIT_REPOSITORY git@github.com:micaah42/QR-Code-generator.git
    GIT_TAG master
)
FetchContent_MakeAvailable(qrcodegen)

If you have any notes or want something fixed let me know :)

[lexuanquynh]

Support for MACOS and iOS:
https://github.com/leetal/ios-cmake

[AlexisCompain]

This will only work for compiler that accepts this options (gcc/clang) but won't work for MSVC for example

I use this variant that is compatible with msvc too

if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
    add_compile_options(/W4 /EHsc)
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    add_compile_options(-Wall -Wextra)
endif()

Note: additionally use add_compile_options instead of set for beter portability

[DerDakon]

And please don't add -Werror. When I build this next year and my gcc18 suddenly comes with new warnings this will need patching. Instead do:

set(CMAKE_COMPILE_WARNING_AS_ERROR On)

This was introduced in 3.24 and will just do nothing in older versions. This can then easily be disabled from the command line:

cmake --compile-no-warning-as-error …

[Neustradamus]

@nayuki: Have you seen this PR?