Add cmake driver

[zhaihj]

Add a simple cmake driver.
can be used by

rock --driver=cmake sourcefile.ooc

This works for rock's source.

[zhaihj]

I found that sometimes Driver won't copy some c source files.
Both make and cmake drivers fail because of this but direct compilation works.

For example:

Name: foo
Description: fooooo
SourcePath: source
Requires: sdl2, stb-image, stb-vorbis

and source file:

use foo
// then do something with stb image/vorbis

compiling this with rock -vv will show that:

CMake driver
Copying /home/housezet/complier/official/rock/sdk/lang/Array.h to build/rock_tmp/ooc/sdk/Array.h
Copying /home/housezet/.ooc_libs/ooc-stb-image/source/stb/stb_image.h to build/rock_tmp/ooc/stb-image/stb_image.h
Copying /home/housezet/.ooc_libs/ooc-stb-image/source/stb/stb_image.c to build/rock_tmp/stb-image/source/stb/stb_image.c
Writing to build/CMakeLists.txt

It shows that the c sources of stb-vorbis is not copied.

CMake Error at CMakeLists.txt:76 (add_executable):
  Cannot find source file:

    rock_tmp/stb-vorbis/source/stb/stb_vorbis.c

  Tried extensions .c .C .c++ .cc .cpp .cxx .m .M .mm .h .hh .h++ .hm .hpp
  .hxx .in .txx

Make driver also fails on this.

[zhaihj]

Some changes to front/CommandLine

CMake needs a project name but current dummy module does not have a name (it is set to "" explicitly)
The last commit make it comes with name same as use-file.
Now cmake driver can compile use file to library.

[zhaihj]

Fix the problem that rock does not copy c sources in uses' requirement

When we directly compile *.use file(which usually means compile to library), requirement is not properly added to dummy module. This commit fixes it.

[zhaihj]

I found that MakeDriver do not have the ability of compiling to library. When we compiling a use file without main, it still tries to generate executable. And also there's no option for generate static/shared library. ( May be I missed something? )
The following patch make driver add extensions for library, use gcc -shared or ar to generate library when module is dummy.

[zhaihj]

Commit zhaihj@ff24719 does not really work...
I'm considering revert it

[fasterthanlime]

style note: try to avoid braceless single-statement ifs on single lines.

Ie:

if (something) {
  somethingElse()
}

or

if (something) somethingElse()

But not:

if (something)
  somethingElse()

Mostly because it makes it easy to add more things in the if block.

[zhaihj]

Thanks, I will fix it.

[zhaihj]

Revert zhaihj@ff24719 and fix the problem.
It seems the reason is that related libraries in UseDef requirements are not collected.

[zhaihj]

typo...

[zhaihj]

another typo

[zhaihj]

Everything seems good.

[zhaihj]

CMakeDriver updated

Sometimes some flags may not work.
Such as the "-m32" flag on compitur without gcc-multilib
We should check if they are usable before adding them to C_FLAGS
Current this check is only performed on embedded flags, for extern flag, I think it is user or pkg-config's work.

This may be related to: #758

For example, now make file will check -m flag:

if(CMAKE_SIZEOF_VOID_P EQUAL 8)
    SET(CMAKE_DET_ARCH_FLAG "-m64")
else()
    SET(CMAKE_DET_ARCH_FLAG "-m32")
endif()
IF(NOT "${CMAKE_DET_ARCH_FLAG}" MATCHES "-m64")
    message(WARNING "You have arch ${CMAKE_DET_ARCH_FLAG} but -m64 is used.")
ENDIF(NOT "${CMAKE_DET_ARCH_FLAG}" MATCHES "-m64")
check_c_compiler_flag(-m64 FLAG_m64)
if(FLAG_m64)
    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -m64")
endif(FLAG_m64)

[zhaihj]

Flag check is fragile. When using -m32 on x86-64 machines, cmake fails to check all flags after -m32.

And also, I'm trying building rock with tcc, but it always fails without any error message...

[zhaihj]

Todo:
MSVC does not work ( because it does not even support search path like /usr/local/include
libGC can not be detected with cmake-gui for windows (works under mingw/msys though)
Arch check is fragile
Remove arch flag for xcode
-pg flag should also be used for link

[zhaihj]

This does not really solve the problem.
According to this
http://public.kitware.com/Bug/bug_relationship_graph.php?bug_id=14736
"Automatically Select Architectures" seems a bug of cmake.

[fasterthanlime]

@zhaihj I merged your work so far. Seems to work to build rock indeed! Haven't tried other, more convoluted projects.

The reason I was prudent approaching a CMake driver is that I didn't want it to be "dumb" — ie. directly copying include paths & lib paths to the CMakeLists.txt would've been bad. I see you're using FindPkgConfig, which takes care of that, so, good!

I'm sure we'll run into other problems in the future, but for now I think this version is a good start.