Compile lua by C++ compilers to avoid memory leaks

[PragmaTwice]

The clause by C++ compilers just means in C++ mode since most mainstream C compilers are also a C++ compiler. 😆
Close #609.

[PragmaTwice]

There are some weird problem in the default xcode toolchains (i.e. apple clang):

$ echo "#include <assert.h>" | /Applications/Xcode_13.2.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -c -
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated [-Wdeprecated]
a.c:1:10: fatal error: 'assert.h' file not found
#include <assert.h>
         ^~~~~~~~~~
1 error generated.

So I try to use clang++ in PATH as cxx compiler instead.

[git-hulk]

@PragmaTwice Seems ${CMAKE_CXX_COMPILER} will use the apple-clang and $CXX will use clang++, clang++ works good after updating the Lua. So we can replace ${CMAKE_CXX_COMPILER} with ${CXX} in lua.cmake?

[PragmaTwice]

@PragmaTwice Seems ${CMAKE_CXX_COMPILER} will use the apple-clang and $CXX will use clang++, clang++ works good after updating the Lua. So we can replace ${CMAKE_CXX_COMPILER} with ${CXX} in lua.cmake?

I think the concern here is that we'd better to keep the same c++ compiler during the whole build process. So I pass the c++ compiler specified by cmake to make.

[git-hulk]

@PragmaTwice Seems ${CMAKE_CXX_COMPILER} will use the apple-clang and $CXX will use clang++, clang++ works good after updating the Lua. So we can replace ${CMAKE_CXX_COMPILER} with ${CXX} in lua.cmake?

I think the concern here is that we'd better to keep the same compiler during the whole build process. So I pass the c++ compiler specified by cmake to make.

I got your point, but it will fail to build if we didn’t specify them explicitly. I’m not sure if it’s ok to other users.

[PragmaTwice]

@PragmaTwice Seems ${CMAKE_CXX_COMPILER} will use the apple-clang and $CXX will use clang++, clang++ works good after updating the Lua. So we can replace ${CMAKE_CXX_COMPILER} with ${CXX} in lua.cmake?

I think the concern here is that we'd better to keep the same compiler during the whole build process. So I pass the c++ compiler specified by cmake to make.

I got your point, but it will fail to build if we didn’t specify them explicitly. I’m not sure if it’s ok to other users.

It is a common usage to specify CMAKE_CXX_COMPILER before build e.g. cmake .. -DCMAKE_CXX_COMPILER=/some/path/some-g++, so I think using CXX may lead to different compilers in one build.
I think we can use try_compile to workaround it: if it is in osx and try_compile(a code snippet with <assert.h>) fail, we will use CXX, otherwise we use CMAKE_CXX_COMPILER to keep C++ compiler unchanged.
These logics are easy to implement in cmake : )

[PragmaTwice]

It is a common usage to specify CMAKE_CXX_COMPILER before build e.g. cmake .. -DCMAKE_CXX_COMPILER=/some/path/some-g++, so I think using CXX may lead to different compilers in one build. I think we can use try_compile to workaround it: if it is in osx and try_compile(a code snippet with <assert.h>) fail, we will use CXX, otherwise we use CMAKE_CXX_COMPILER to keep C++ compiler unchanged. These logics are easy to implement in cmake : )

done 🎉

[git-hulk]

cool, thanks to @PragmaTwice great work!

[tisonkun]

@PragmaTwice as RocksLabs/lua#3 merged, is it still necessary to introduce such workaround? IIUC now it should be happy to build with CMAKE_CXX_COMPILER.

[PragmaTwice]

I think I figure out this problem.
CMake deals with apple clang well because it automatically adds -isysroot ${CMAKE_OSX_SYSROOT} to compile options.
But Makefiles in lua do not do that, so assert.h cannot be found while using apple clang++.
We can just add it to LUA_CFLAGS!
@git-hulk @tisonkun

[PragmaTwice]

Sorry for many time to solve it, I do not have an Mac osx device so I use github actions in a temp repo to debug the build process.

[tisonkun]

Great work! Thanks for your contribution.

[git-hulk]

Thanks for @PragmaTwice great investigation and contribution again. 👍