I am using Visual Studio 2017 and need to create code that is compatible to VS2008 (C++03 or C++98). Is there a switch to restrict MSVC to C++03 features?
I am using CMake and tried to set
set_property(TARGET tgt PROPERTY CXX_STANDARD 98)
But this seems only to make sure, that the compiler supports C++98 or newer.
Any solution, that checks if C++ code uses features that are newer than the features supported by VS2008 will work as well. I just need to make sure, that I do not accidentally use features that are too new.
MSVC only got the standard switch in one of the updates to VS2015 (Update 3 to be exact) which was more or less C++14 compliant, and as such there are only switches for standards starting with C++14 (plus a few later features that were already implemented at the time of the update). All older features are enabled unconditionally for backwards compatibility (and because of all the work required to retrofit already implemented features for previous standards for virtually no gain).
See this blog post for more information: https://devblogs.microsoft.com/cppblog/standards-version-switches-in-the-compiler/
Also, note that there were a lot of conformance improvements in newer versions of MSVC, so even with the std switches you could write code that wouldn't work or would behave differently on older compiler.
A better solution would be just to use VS2008 toolset from VS2017 visual studio, as explained here: https://devblogs.microsoft.com/cppblog/stuck-on-an-older-toolset-version-move-to-visual-studio-2015-without-upgrading-your-toolset/
That way you'll be certain your code compiles on the older toolset, while using up-to-date IDE.
Related
I use Visual Studio 2019 for C++ development. Due to constraints of legacy systems that code will be deployed to, I am limited to using only C++11 language features (specifically GCC 4.8.5).
The default in VS2019 is C++14, which is obviously a super set of C++11. I can't see a way to specify C++11 only. This would be useful as a much faster way to see if I accidentally include newer C++ features than seeing things fail in the build system.
Is there any way to change this setting?
I am afraid it's not possible.
there is no plan to add a C++11 switch
Link: Standards version switches in the compiler
The compiler doesn't support standards options for C++98, C++03, or
C++11.
/Zc:__cplusplus
Is the c++ version you use tied to the version of compiler you have or IDE?
If it isn't either of those, how do I use c++ 11 on my IDE? How do i update what C++ version i use in my programs?
How do I check what version I'm using?
I know that printing the __cplusplus variable can tell me what version I'm using, but this doesn't answer my other questions, neither does it answer my third question, because: https://stackoverflow.com/a/14131551/10938047
Found this question, with the answer containing an outdated link.
Visual Studio 2012 __cplusplus and C++ 11
The C++ version you can use is obviously tied to the compiler you use. If your compiler doesn't support some newer standard then of course you cannot use it.
As for IDEs; some IDEs are tied to a specific compiler, some can use different ones.
Some compilers support multiple language versions but require you to explicitly enable anything newer than what they enable by default. For example; most older versions of GCC support C++17 just fine, but default to C++11 or C++14 unless you tell them to enable C++17 support via the -std=c++17 command line option.
The /std (Specify Language Standard Version) option is available in Visual Studio 2017 and later. Does it mean that previous versions of Visual Studio use particular versions of the C++ standard and, unlike gcc/clang, there's a 1:1 mapping between a VS version and the default C++ standard version provided by the compiler?
There is a blog post Standards version switches in the compiler that explains the introduction of the feature and what MSVC used to do previously:
Traditionally, we would release the compiler in a default mode that combines features striding several versions of the C++ language, e.g. C++98, C++03, C++11, C++14, etc. in addition to conformance improvement bug fixes. This can lead to situations where it is difficult to simultaneously upgrade to the newer and better compiler and at the same time move your code forward. We really appreciate the great feedback you’ve given us about our conformance improvements and new feature work. As the C++ standards committee is gearing up for a new C++ version, we’ve taken the initiative to help you state in your build systems or compiler command lines which version of C++ you are comfortable with while updating to the next version of Visual C++.
Visual C++ has made significant progress towards C++ standards conformance between the first release of Visual Studio 2015 and VS 2015 Update 3. We’ve fixed many issues with constexpr, improved expression SFINAE support, evaluation of initializer lists, variable templates, and more. Our standard library implementation has kept pace with features adopted into the post-C++14 standard draft. And we’ve implemented some major features currently under consideration by the committee, including C++ modules and coroutines. We want you to benefit from all this, but also we want you to consume these features at your own pace, while upgrading to this new update.
All post-C++14 features implemented in this update are off by default; those which were included in previous releases are left on to avoid causing your builds.
...
From what I gather /std:c++17 would be equivalent to clang/gcc -std=c++17 argument.
Some versions of msvc may not fully implement some versions of iso C++.
Depending on the Visual C++ compiler version or update level, certain C++14 or C++17 features may not be fully implemented or fully conformant when you specify the /std:c++14 or /std:c++17 options. For example, the Visual C++ 2017 RTM compiler does not fully support C++14-conformant constexpr, expression SFINAE, or 2-phase name lookup.
(cf: https://learn.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=vs-2017 )
So that's not exactly a "1:1 mapping between VS version and the default C++ standard version provided by the compiler".
You shouldn't rely on that.
Instead you should read the docs for the version of VS you're using.
Hope this answers your question.
I am trying to install MongoDB driver and is reading this following section
https://github.com/mongodb/mongo-cxx-driver/wiki/Download-and-Compile-the-Legacy-Driver
SCons Options when Compiling the C++ Driver
Select options as appropriate for your environment. Please note that some flags may not be available on older versions.
Important note about C++11/C++14: The boost libraries do not offer a stable ABI across different versions of the C++ standard. As a result, you must ensure that your application, the C++ driver, and boost are all built with the same language standard. In particular, if you are building the C++ driver with C++11 enabled, you must also build your application with C++11 enabled, and link against a C++11 compiled boost. Note that on most systems, the system or package installed boost distribution is not built with C++11, and is therefore incompatible with a C++11 build of the legacy driver.
Important note about the C++ standard library: Much like the C++11 issues, it is again critical that all three components (your application, boost, and the C++ driver) be built against the same C++ runtime library. You cannot mix components that have linked against libc++ with those that have linked against libstdc++.
Important 26compat Note: If you are using the 26compat branch, the install-mongoclient target is only enabled when the --full flag is provided. Similarly, you must use the --use-system-boost flag when building 26compat.*
My main question, I am trying to find out what standard my visual studio 2015 is running on when I build solution. I have tried to read around but I think I misunderstood the concept of C++11 and C++14. On Microsoft page it mentioned that VS2015 supports C++11,C++14 and C++17. But how do I know what am I using now? I can't find a way to explicitly configure. I am new to C++ and have been coding Java for many years. C++ is confusing to me because there are so many variety such as compilers and standards. Please help me understand and possibly find out what standard I am running.
The text is mostly nonsense.
ABI's are dictated by compilers, not standards. There is no ABI for C++11, there's one for GCC and a different one for MSVC2015.
"C++11 enabled" is a setting on GCC, and it does affect their ABI. The same applies to libc++ versus libstdc++, neither is part of the C++11 standard. Also, the mixing of build environments and the OS ("system Boost version") is mostly a Linux thing.
MSVC++ isn't GCC, and it doesn't use libstdc++, so all this does not affect you. And Boost versions aren't even a MSVC++ setting anymore, for the last few versions library configuration has been a per-project setting instead. (Tip: Create a Boost.vsprops file for that)
Does C++0x mode in VC++ 2010 has an off switch? I am working on a project that supposed to compile on non 0x compilers, and therefore I want to compile against the current standard. (Even if non of the new features are being used directly, there are still subtleties that makes C++0x more premissive).
The closest switch I found was Configuration Properties -> C/C++ -> Language -> Disable Language Extensions but that's not it.
No, language extensions are typically non-standard vendor specific additions.
C++0X features: There is no direct way to switch off these features. One workaround is to not use them. However, note that there will still be marked difference in performance across versions of VC runtime. VC10 implements move semantics and the standard library (std::string for example) uses these features generously.
A reasonable compromise in my opinion is to switch back to VS2008. Recent VS versions have been notoriously buggy (so far, in my experience) and have never worked the way they should without a Service Pack. VS2008 is pretty stable now, without any of those C++0x features and ought to fit your bill.
It appears you can use the vc2008 toolset in VS2010 see: Visual C++ 2010 compatibility with VC 2008