Compiling from Visual Studio 2012 to g++? - c++

I have a c++ program compiled in Visual Studio 2012. It contains the boost library. Now, I want to compile this using the g++ compiler. What are the things I must be aware of? Things that will most likely silently break my code in random places.
For example I was always assuming long is 4 bytes buy g++ treats this as 8 bytes. For this alone I need some changes.
And what version of gcc to use, 4.7.3, 4.6.4 or 4.8.2?

if you wrote valid and good C++ code without using specific libraries you should be aware of nothing.

Some of the things that you have to keep in mind. This list is not comprehensive but are those things that are on top of my mind when I read your question.
pragma once : When using g++, you should gaurd file inclusion by using #ifndef, #define and #endif guards.
Header inclusion : VS 2012 is very lenient and does not make a fuss of forward or backward slash while including headers. g++ will be strict in enforcing them.
If you are using Win32 threads / mutex, it is best to shift to std::thread. If you are using boost for threads, you are OK.
The version of gcc you can use and get away with depends on your usage of C++11 features. gcc was always ahead of Microsoft in implementing C++11 features and you should be OK with an older version of gcc too. I cannot answer this question unless I understand what c++11 features you are using in your code. It is safe to say that the more recent version of gcc will surely support what is available in Vs 2012.

Related

std::bind compiler error gcc

In one of my recent projects, I did the development work on Ubuntu (cmake+gcc 4.8.4). The code builds fine. However, when I attempt to build the same code in cygwin (cmake + gcc 5.3), I get a compiler error for std::bind. This goes away on doing a #include <functional>. However, this worries me a little bit. I expect my code to work fine on identical or very similar compilers.
I have just shipped out a piece of code which will be used on a CentOS. I just assumed that because my code builds fine with Ubuntu, other linux distributions with a similar compiler should not be a problem. However, I am no longer sure if my code will build fine on CentOS.
My question is this. Can I assume that if my code builds fine with a particular version of gcc on my Ubuntu machine, it will also build fine on other linux distributions with the same or higher version of gcc? Or am I being overly optimistic and should rely more testing? Or this has something to do with std::bind itself?
There is no guarantee that all gcc compiler versions behave the same. In particular w.r.t. C++ 11 features there were some incompatible changes between the compiler versions. gcc 4.8 had still only experimental C++ 11 support. The standard says that std::bind comes with <functional>, so gcc 5.3 correctly demands you to include it:
http://en.cppreference.com/w/cpp/utility/functional/bind
It is possible that older versions of gcc either included <functional> in some other include you have, or that bind was provided in another include.
It is always a good idea to test software on different compiler versions and even with a completely different compiler (like clang). Otherwise you might use extensions or small deviations from the C++ standard without knowing it and thus be tied to that particular compiler version.
If you forgot to include <functional> before using std::bind, your code is not standard-compliant, and has no guarantee to work anywhere. That it worked on your particular toolchain is unfortunate luck.
My question is this. Can I assume that if my code builds fine with a particular version of gcc on my Ubuntu machine, it will also build fine on other linux distributions with the same or higher version of gcc?
No you cannot. Your version may have had a bug that allows a piece of non conforming code to compile and the later version could have that fixed which would lead to a compiler error for that offending code.
In fact this is basically what happened to you. It is not really a bug per se but you used a function from a standard header and you never included that header. std::bind lives in <functional>. The fact that it compiled without the inclusion of <functional> is non standard behavior. When you moved to a compiler that did not include <functional> in one of the header you do include it broke the compilation.
Or am I being overly optimistic and should rely more testing?
Yes you should test the code on multiple compilers and systems if you are trying to release truly portable code. Your best defense is to write strictly 100% standard conforming code.
Or this has something to do with std::bind itself?
This has nothing to do with std::bind but with how conforming you make you code. Not including <functional> when it is required makes you code non conforming.

Porting from Code::Blocks to Visual Studio 2010

Say I have a open source C::B C++ (non-C++11, perfectly compatible with the 1998 ISO standard) project I've downloaded which is using MinGW/GCC (TDM-1 4.7.1 or 4.7.2 - doesn't work with newest version),; can I port the source files from it to Visual Studio 2010 and be able to make it work without massive code rewriting? Or there are certain cases in which it won't be possible? Or it depends on various things?
EDIT:
The code relies on additional external utilities and libraries such as:
Lua
SDL 2.0 + SDL Image 2.0
OpenGL
The most General and correct response is: It depends on various things.
What kind of project are you refering to? Is it wxWidget, QT4, GTK+, OpenGL?
How much do you use c++11?
Assuming that we are talking about a simple Console Application the easiest way to verify whether you can migrate to MSVC2010 is to switch compiler inside Code::Blocks project.
Select Project->Build Option... and under Selected compiler choose Microsoft Visual Studio C++ 2010. Afterwards try to recompile. The warning and errors will show you how easy will be the porting.
Of course you have to install Code::Blocks with MSVC2010 too.
EDIT: The OpenGL library is supported by MSVC2010 and libsdl has VC development libraries. However, things seem to be more complex with Lua. My guess is that you might start a substantial porting work here.
If the project was written using portable C++98 code you shouldn't have too much trouble. First, I would check you can compile in GCC with -std=c++98 -pedantic flags and fix any warnings to ensure you are not relying on any GCC extensions.
It also depends on the portability of any required libraries.
Try it!
If your code is standard-compliant and does not rely on any GCC extensions or GCC-specific libraries, then you should be fine out-of-the-box.
Note though that different compilers support C++ in different ways; for example, even Visual Studio 2013 has only passing C++11 support so if your program is a C++11 program with things like ranged-for and initializer lists in it then, depending on the version you're using, it's just not going to work without those pieces of code being rewritten to look more like C++03.
I actually made a mistake:
C::B indeed told me there were multiple errors in the compilation attempt with the MSVC2010 compiler, because the code included many Unix-only libraries, too intricately so to be easily avoided. Thus, I'm thinking of either making MinGW/GCC work in Visual Studio itself or sticking with C::B.
(Continues here: POSIX Headers (from MinGW project) in Visual Studio 2013)

C++11 on Windows

I'm wondering how well writing software in C++11 works on Windows yet. It would be most comfortable (and propably most natural) to use one of the native compilers for Windows - I'm thinking about Visual Studio 2012 Express or Visual Studio 2013 Express here. Everything I could find so far on that matter is
http://msdn.microsoft.com/en-us/library/vstudio/hh567368.aspx
(Comparison of C++11 features of VC10 and VC11, which seems to be quite bad)
http://blogs.msdn.com/b/vcblog/archive/2013/06/28/c-11-14-stl-features-fixes-and-breaking-changes-in-vs-2013.aspx (not really transparent, didn't give me a good idea how well it works)
Does anyone have any experience how well the current Visual Studio versions can handle C++11? I really want to start using auto, lambdas, variadic templates, template aliases, initializer lists and rvalue references (to name just a few) and all the other good stuff right now, but if Windows might be a problem I might have to use C++03 further.
Another possibility seems to be to install LLVM and Clang on Windows. My primary platform is OSX, and on that system Clang's support for C++11 is really good. But I read that the LLVM-version of the standard library for C++ (libc++) does not work well on Windows. So LLVM/clang might not be an option.
What are your opinions on C++11 development on Windows?
Thank you!
I can only give you my experience as a developer, as I've been building against the cutting edge of C++ on Windows using Visual C++ for just about everything, while also installing several other compilers and IDEs (including building Clang myself on Windows for Visual Studio 2012, 2012 CTP, and 2013 Preview). The following is my experience up until right now (August 13th, 2013), and is based on Herb Sutter's talk and working with the compiler every day.
The Quick
Run in the opposite direction of Visual Studio / VC++. Support for C++11 is slow, and they're currently being crushed in terms of compiler features versus Clang and GCC.
The Present
Visual C++'s C++11 (and C++14 support) is beyond abysmal right now. They lack powerful features that make template metaprogramming in C++ great (using expressions in particular).
Using doesn't exist right now. I have spent hours and hours porting great C++11 code with using to VC++, only to have it break it certain places, snap, or just become near damn unmaintainable.
Variadic support in the CTP was horrifically terrible, and while it got better for Visual Studio 2013 Preview's version of the compiler, it's still fairly bad at complex variadic and template expressions that obey the standard (and compile fine in GCC and Clang).
=delete and =default are pretty much gone from VC++ right now; in the hopeful near future, maybe it will work out (and it should come "soon-ish", according to the roadmap) (I had to implement r-value constructors explicitly for many simple classes all the way down a 8-class inheritance hierarchy once. It was the worst slap in the face, when I watched GCC and Clang users get all of my explicit hardcoded work for free with =default).
As a holdover (primarily because of Windows OS code and some binary compatabilities), Empty-Base-Class-Optomizations in VC++ don't work. Don't expect your class hierarchy sizes or member layout to be optimized in the least (watch your ordering in std::tuple when packing variable types).
This is about all the frustrations I've come into contact with so far. They're work-aroundable -- I have to work with them every day -- but if you want great C++ support, you should jump for GCC or Clang and somehow make it work on your machine.
The Future
If you really want C++11, you will need to wait about a year, and even then Visual Studio 2013's release of VC++ will still be missing a few features (and don't expect them to be bugless either). VC++ for 2013 will also still be critically missing std::move and explicit r-value support in many places, making it painful when you expect things to work.
The Caveat
If you're not a powerful Vim user, you're low on options when it comes to IDEs that you can work with (that play nice with GDB/GCC or Clang).
QtCreator is nice, works with MinGW, and is generally fully featured enough to get work done.
Sublime Text can be used, but you'll have to write your own building system or delegate that to something else.
Code::Blocks's autocomplete is wonky and behaves strangely, and the IDE itself feels clunky.
Eclipse is supposed to be good, but my experiences with it are clunky and strange, with odd input lags at time (despite a 8.00 GB i7 Haswell machine using an SSD).
Visual Studio, as an IDE, is pretty solid. Then stack Visual Assist X on top, and it works pretty damn well for C++ coding. It's really the only reason I continue to stick with it, but I've already made headway into learning Vim so I can mostly ditch Visual Studio altogether, when the time comes.
About Libraries
Library support in VC++ is pretty complete (for as much as their broken compiler lets them be complete). It has regex, while most other libraries have non-existent or broken regex support. But that doesn't mean that the VC++ library plays nice with some C++11 features that it says it does (picture by melak47).
And Lastly
If you want code that you know is going to work in Windows, 100%, for the rest of eternity, you'll probably want to program against VC++. The other "benefit" is that the code you write in VC++ is the smallest subset of C++/C++11 you can write with, so in the end it should compile everywhere. Of course, that goes against the very idea of using beautiful C++11 and enjoying it, so... pick your poison(s) wisely.
VC's C++11 support is far from complete, but it does include the most important user-facing features.
And here's the other thing. In my experience, it is fine to install MinGW or Clang on Windows, but you're going to have some inconvenience because hardly anybody precompiles binaries for those compilers for Windows (whereas lots of people precompile binaries for Visual Studio).
In addition, there are as far as I am aware no environments for Windows which are remotely as advanced as Visual Studio for things like graphical debugging, intellisense, and stuff like that. When I tried Code::Blocks it just didn't work, realistically.
You can see here for a comprehensive comparison of compiler support for C++11 language features. Here's some info on VS's C++11/14 roadmap.
MSVC is lagging behind the other major C++ compilers but it's still got support for many of the most important features.
auto, lambdas, and rvalue references are available from VS10. IIRC there's a caveat with rvalue references that the compiler doesn't generate move construction and move assignment operators.
variadic templates and initializer lists are available in the VS2013 preview, including library support.
type aliasing (i.e., typedefs with the using keyword) is expected to be available in VS 2013 RTM.
If you don't need to interoperate with binaries generated by VS then installing another compiler such as GCC is workable. I understand Clang can also work in a mingw environment, with libstdc++ rather than libc++.
http://nuwen.net/mingw.html
The nuwen distro is AWESOME! It is MinGW but it comes out much quicker than MinGW as new GCC releases come out. It also comes with all of boost and other useful libraries already compiled. It is all I use on windows anymore.
We are using C++11 for a few months already in production software across windows and linux in some here.com products without any problems. We use auto, lambdas, range for... Using Visual studio 2012 and gcc 4.7.
I have been using VS2012 and used C++11 features where possible. There are some bugs in the implementations and I have found it helpful to have another compiler to hand when I get errors from Visual Studio to compare against.
Clang and GCC to lead the way in terms of C++11 feature support and it appears to be a neck-and-neck race in terms of C++11 support between the two. MSVC is sadly panting trying to keep up and lagging behind. The Nuwen MingGW distro is, as Jake mentions, excellent and appears to be working well with Eclipse (Kepler release) and I didn't encounter too much pain using it with Netbeans 7.4 either. The Nuwen distro is currently at version 11.2 at the time of writing and, as you can see at Stephan's website, is now x64-native, featuring GCC 4.8.1 and Boost 1.54.0, with GCC's default mode also set to C++11.
I'm certainly beginning to use Eclipse Kepler and Nuwen MinGW in preference to MSVC 2012 more and more, but I'm largely a hobbyist C++ programmer still getting my feet wet and may not have hit the more obscure problems that those to whom C++ is their bread and butter may know about.

GCC worth using on Windows to replace MSVC?

I currently develop in C++ on Windows, using Visual Studio 2010. After the official announcement of C++11, I have begun to use some of its features that are already available in MSVC. But, as expected, the great majority of the new changes are not supported.
I thought maybe the upcoming version of Visual Studio would add these new features. However, after reading this it looks like very little is going to change.
And so, I'm curious about the feasibility of using GCC on Windows rather than MSVC, as it appears to support the great majority of C++11 already. As far as I can tell, this would mean using MinGW (I haven't seen any other native Windows versions of GCC). But I have questions about whether this would be worth trying:
Can it be used as a drop-in replacement for cl.exe, or would it involve a lot of hacks and compatibility issues to get Visual Studio to use a different compiler?
The main selling point for Visual Studio, in my opinion, is it's debugger. Is that still usable if you use a different compiler?
Since GCC comes from the *nix world, and isn't native to Windows, are there code quality issues with creating native Windows applications, versus using the native MSVC compiler? (If it matters: most of my projects are games.)
In other words, will the quality of my compiled exe's suffer from using a non-Windows-native compiler?
MSVC has the huge advantage of coming with an IDE that has no equals under Windows, including debugger support.
The probably best alternative for MinGW would be Code::Blocks, but there are worlds in between, especially regarding code completion and the debugger.
Also, MSVC lets you use some proprietary Microsoft stuff (MFC, ATL, and possibly others) that MinGW has no support for, and makes using GDI+ and DirectX easier and more straightforward (though it is possible to do both with MinGW).
Cygwin, as mentioned in another post, will have extra dependencies and possible license issues (the dependency is GPL, so your programs must be, too). MinGW does not have any such dependency or issue.
MinGW also compiles significantly slower than MSVC (though precompiled headers help a little).
Despite all that, GCC/MinGW is an entirely reliable quality compiler, which in my opinion outperforms any to date available version of MSVC in terms of quality of generated code.
This is somewhat less pronounced with the most recent versions of MSVC, but still visible. Especially for anything related to SSE, intrinsics, and inline assembly, GCC has been totally anihilating MSVC ever since (though they're slowly catching up).
Standards compliance is a lot better in GCC too, which can be a double-edged sword (because it can mean that some of your code won't compile on the more conforming compiler!), as is C++11 support.
MinGW optionally also supports DW2 exceptions, which are totally incompatible with the "normal" flavour and take more space in the executable, but on the positive side are "practically zero cost" in runtime.
I want to add some information because the field may have changed since the question was asked.
The main problem for switching away from MSVC was the lack of a good IDE that flawlessly integrates with MinGW . Visual Studio is a very powerful tool and was the only player on Windows for quite some time. However, Jetbrains released a preview version of their new C++ IDE CLion some days ago.
The main benefit comes when working on cross platform applications. In this case, a GCC based tool chain can make life much easier. Moreover, CLion narrowly integrates with CMake, which is also a big plus compared to Visual Studio. Therefore, in my opinion, it is worth to consider switching to MinGW now.
GCC's C++11 support is quite phenomenal (and quite up to par with standards conformance, now that <regex> has been implemented).
If you replace your compiler, you'll need to make sure every dependency can be built with that new compiler. They're not made to be substitutable plugins (although Clang is working on becoming that way).
GCC is a fine compiler, and can produce code that has pretty much the same performance, if not better, than MSVC. It is missing some low-level Windows-specific features though.
Apart from this, to answer your questions:
To get VS to use GCC as a compiler, you'd pretty much need to turn to makefiles or custom build steps all the way. You'd be much better off compiling from the commandline and using CMake or something similar.
You cannot use the VS debugger for GCC code. GCC outputs GDB compatible debug information, and the VS debug format is proprietary, so nothing will change in that area anytime soon.
Code quality is just as good as you'd want it. See above.
No, the quality of your code will actually increase, as GCC will point out several assumed standard extensions MSVC would hide from you. All self-respecting open source projects can be compiled with GCC.
I my humble opinion, it's depends how someone started to code in the first place. I've been using g++ and gcc for more than 20 years now but the reason why i keep using gcc is mainly for licensing reasons. Although i like it too when i don't have a bunch of runtime dependencies or dll's to bundle with my stuff since i came from the DOS era, i still like my stuff small and fast. gcc for windows comes with standard win32 libraries and common control but i had to develop my own win32 controls for stuff that might require mcf shit to work properly or just to look nicer.
Although gcc might have strong support over internet, when it comes to win32 stuff, many rely on mcf and vc proprietary stuff so again, one may have to work his own issues around and be creative when difficulty arises.
I think it's all about needs and circumstances. If you are just a hobbyist coders and have the time for researches, creating you own libs and stuff but you want a solid compiler that's around since the late 80's and free, gcc sound perfect for the job.
But in the industry visual studio is a must if you want to be competitive and stay in the race. Many hardware manufacturers would prefer bundling visual studio compatible libraries for they hardware over some opensource gnu stuff.
That's my two cents.
To be honest, C++ should be handled with MS Visual Studio. If you want to make cross-platform or Unix apps, use GCC. GCC works and can be used with any IDE other than Visual Studio. Even Visual Studio Code can use GCC. Code::Blocks, Eclipse IDE for C/C++ developers, CLion, Notepad++ and even the good ol' tool we've always known, Notepad works with GCC. And finally, on a PC with low disk space, installing Visual Studio's "Desktop Development with C++" is something like 5 GB, if it was to be useful. And this is where GCC hits MSVC hard. It has native C support. MSVC can compile C, but only with a lot of fine-tuning. It takes a lot of time and effort to finally be able to compile. The final verdict:
If MSVC works, it hella works! If MSVC doesn't work, it HELLA DON'T WORK.
If GCC installs, it works, and if it doesn't work, it's the IDE's problem.
GCC is for people who don't mind spending 4 hours at the computer making it work properly. MSVC is for those who don't care about C and want it to install without any pokin' around.
It can't be used as a direct swap-out replacement for the microsoft compilers, for a start it has a vastly different set of command line arguments and compiler specific options.
You can make use of MinGW or Cygwin to write software but introduce extra dependencies ( especially in the case of cygwin ).
One not often touted advantage of gcc over cl is that gcc can be used with ccache to drastically speed up rebuilds or distcc to build using several other machines as compiler slaves.
Consider the Intel compiler (or "Composer" as they seem to have taken to calling it) as another option. I'm not too sure where its C++11 support is at compared with MS (certainly it has lambdas), but it does integrate very nicely with VisualStudio (e.g different projects within a solution can use the Intel or MS compilers) and there's also been some efforts made to match the MS compiler commandline options.
GCC and MSVC use different name mangling conventions for C++. C++ dlls compiled by one compiler can not be used in applications compiled with the other. I believe this is the main reason we don't see more widespread use of gcc in windows.

Using Visual C++ with a different C++ compiler?

I like the Visual Studio IDE. I'm used to it and find it is the best IDE I've ever tried. We also find increasing use of C#/.NET here.
However, after the underwhelming announcement regarding C++11 features in VS11 I'm looking into replacing the compiler.
It seems that the Intel compiler fully integrates with VS but that doesn't mean it will compile our Windows code. I don't know how I'd fare with a try of g++ or clang
Can VS actually be productively used with a different C++ compiler to compile Windows code, that is legacy code using all kinds of Win32 / MFC / COM stuff?
Depends on how much use you made of the Microsoft-proprietary extensions. Things like #pragma once tend to be supported by all the major compilers, but the weirder COM things (e.g., #import and anything C++/CLI) probably won't be. No idea if MFC will build under the new compiler, but you'll probably have to link it statically or ship your own DLL; G++ definitely uses a different mangling scheme than MSVC.
I'm not sure how easy it is to replace cl.exe and keep your vcproj files intact (though some compilers actually do it), but there are always Makefile projects.
I have never actually worked with the Intel C++ compiler, but I see no reason why it wouldn't compile the code that VC++ does. Here is official Intel documentation.
I use Visual Studio 2008 with a Makefile project to cross-compile; no reason you couldn't do the same with a different Windows compiler.