How to manage C++ standard
Warning
This feature is experimental
The setting representing the C++ standard is cppstd
.
The detected default profile doesn’t set any value for the cppstd
setting.
The consumer can specify it in a profile or with the -s
parameter:
conan install . -s cppstd=gnu14
This setting will only be applied to the recipes specifying cppstd
in the settings
field:
class LibConan(ConanFile):
name = "lib"
version = "1.0"
settings = "cppstd", "os", "compiler", "build_type", "arch"
Valid values for compiler=Visual Studio
:
VALUE |
DESCRIPTION |
---|---|
14 |
C++ 14 |
17 |
C++ 17 |
Valid values for other compilers:
VALUE |
DESCRIPTION |
---|---|
98 |
C++ 98 |
gnu98 |
C++ 98 with GNU extensions |
11 |
C++ 11 |
gnu11 |
C++ 11 with GNU extensions |
14 |
C++ 14 |
gnu14 |
C++ 14 with GNU extensions |
17 |
C++ 17 |
gnu17 |
C++ 17 with GNU extensions |
Build helpers
When the cppstd
setting is declared in the recipe and the consumer specify a value for it:
The CMake build helper will set the
CONAN_CMAKE_CXX_STANDARD
andCONAN_CMAKE_CXX_EXTENSIONS
definitions, that will be converted to the corresponding CMake variables to activate the standard automatically with theconan_basic_setup()
macro.The AutotoolsBuildEnvironment build helper will adjust the needed flag to
CXXFLAGS
automatically.The MSBuild/VisualStudioBuildEnvironment build helper will adjust the needed flag to
CL
env var automatically.
Package compatibility
By default Conan will detect the default standard of your compiler to not generate different binary packages.
For example, you already built some gcc > 6.1
packages, where the default std is gnu14
.
If you introduce the cppstd
setting in your recipes and specify the gnu14
value, Conan won’t generate
new packages, because it was already the default of your compiler.
Note
Check the package_id() reference to know more.