C++17

Usage status

This table lists C++14 and C++17 features and whether they can be used in Inkscape or not (yet). Add C++14 or C++17 features that you would like to use to the table, so that we know what to test for to increase the C++17 "allowance".

See also C++11, C++20

Feature	Since	Can use?	Comment
std::move and rvalues	C++11	from 1.0	Allows passing ownership of internal resources between objects
enum class	C++11	from 1.1	Strong enum constants (take the name of the enum, can't be implicitly converted to int)
std::make_unique<Foo>(…)	C++14	from 1.1	Replaces std::unique_ptr<Foo>(new Foo(…))
constexpr	C++14	from 1.1	Declares a variable as usable in a const expression
if constexpr	C++17	from 1.1	Guarantees the branches will be decided at compile-time
std::variant<…>	C++17	from 1.1	Type-safe union, where the contained type is known at runtime
std::optional<…>	C++17	from 1.1	Object type (not a pointer or reference) which can either exist or be std::nullopt
auto [x, y] = foo();	C++17	from 1.1	Structured binding, for returning more than a single value
namespace A::B::C	C++17	from 1.1	Nested namespaces
inline static const int	C++17	from 1.1	Inline variables (inside header files)
std::filesystem	C++17	not yet	Filesystem library (may not be useful as we are using Gio::File). Also only supported from gcc 8, and Ubuntu 18.04 only has gcc 7.
toxic feature of doom		NO	Never use this (in case we stumble upon C++14/C++17 features that we really don't like)

Platform status

We need to keep coordinated with the section on Distro Dependencies.

Also see this page:

• http://en.cppreference.com/w/cpp/compiler_support

Note that __cplusplus is always 1 for GCC 4.6 that is used on Windows. So #if __cplusplus < 201103L or variants does not work to choose between C++03 or C++11 code.

C++17 is well supported by all major compilers.

Compiler version when feature complete:

	GCC	Clang	MSVC
C++17	7 (2017)	4 (2017) (5 for constexpr lambda expressions)	19.14 (2017)
C++20	10* (2020)	10* (2020)	19.25*
C++23	12#	14# (2022)	19.32#

'*' Mostly complete '#' About half complete