Difference between revisions of "C++20"

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(Update for Ubuntu 24.04)
 
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See also [[C++11]], [[C++17]].
See also [[C++11]], [[C++17]], [[C++23]].


Some things that will be interesting to use once C++20 is common:
Some things that will be interesting to use once C++20 is common:
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| <code>std::lerp</code>            || C++20 || style="background: lightgreen;" | from 1.4  ||  9    || 11.0.3 || Linear interpolation. (ui/tools/pencil-tool.cpp)
| <code>std::lerp</code>            || C++20 || style="background: lightgreen;" | from 1.4  ||  9    || 11.0.3 || Linear interpolation. (ui/tools/pencil-tool.cpp)
|-
|-
| <code>std::bit_floor</code>      || C++20 || style="background: lightgreen;" | from 1.4  || 9/10  || 11.0.3/13.0.0 || Compute floor(log2(x)). (helper/mathfns.h)
| <code>std::bit_floor</code>      || C++20 || style="background: lightgreen;" | from 1.4  || 9/10  || 11.0.3/13.0.0 || Compute <code>floor(log2(x))</code>. (helper/mathfns.h)
|-
|-
| <code>Concepts</code>            || C++20 ||                                  from 1.4? || 6/10  || 12.0.0 Partial || Safer templating. (ui/controller.h)
| Concepts                         || C++20 ||                                  from 1.4? || 6/10  || 12.0.0 Partial || Safer templating. (ui/controller.h)
|-
|-
| <code>Coroutines</code>          || C++20 || style="background: pink;" |        not yet || 10    || 10.0.1 Partial,<br/> 15.3 Full || Simpler asynchronous code. (trace/trace.cpp)
| Coroutines                       || C++20 || style="background: pink;" |        not yet || 10    || 10.0.1 Partial,<br/> 15.3 Full || Simpler asynchronous code. (trace/trace.cpp)
|-
|-
| <code>std::make_unique_for_overwrite</code>
| <code>std::make_unique_for_overwrite</code>
                                     || C++20 || style="background: pink;" |        not yet || 11    || 15.0.0 || Don't zero arrays allocated using std::make_unique. (util/pool.cpp)
                                     || C++20 || style="background: pink;" |        not yet || 11    || 15.0.0 || Don't zero arrays allocated using std::make_unique. (util/pool.cpp)
|-
|-
| <code>Ranges</code>              || C++20 || style="background: pink;" |        not yet ||        || ? || for (init; decl : expr). (ui/dialog/swatches.cpp)
| Ranges                           || C++20 || style="background: pink;" |        not yet ||        || ? || (ui/dialog/swatches.cpp)
|-
|-
| <code>[https://stackoverflow.com/a/60244416/5075760 Structural templates]</code>
| [https://stackoverflow.com/a/60244416/5075760 Structural templates]
                                     || C++20 ||                                  from 1.4? ||        || Partial || Allow instances of arbitrary literal classes as template parameters. (display/drawing.cpp)
                                     || C++20 ||                                  from 1.4? ||        || Partial || Allow instances of arbitrary literal classes as template parameters. (display/drawing.cpp)
|-
|-
| <code>Mathematical Constants</code>
| Mathematical Constants           || C++20 ||                                            || 10    || 12.0.5 || Constants like <code>std::numbers::pi</code>.
                                    || C++20 ||                                            || 10    || 12.0.5 || Constants like std::numbers::pi.    
|-
| Heterogenous lookup in <code>std::unordered_map</code>
                                    || C++20 || style="background: pink;" |        not yet ||        ||        || Faster lookup, use of smart pointers as keys.
|-
|<code>consteval static</code> member functions
|C++20
| style="background: pink;" | not yet
|
|
|Guaranteed compile time evaluation of member functions (stronger than <code>constexpr</code>)
|}
|}


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* Apple Clang: https://developer.apple.com/documentation/xcode-release-notes
* Apple Clang: https://developer.apple.com/documentation/xcode-release-notes


As of 27 March 2024, the CI runners for the various supported platforms are
As of 10 July 2024, the CI runners for the various supported platforms are
* Linux:
* Linux:
** appimage:linux: GNU 13.2.0 (building on Ubuntu 23.10)
** appimage:linux: GNU 13.2.0 (building on Ubuntu 24.04)
** inkscape:linux: Same as above
** inkscape:linux: Same as above
* Windows
* Windows
** inkscape:windows:build: GNU 13.2.0 (temporarily disabled since GTK4 port)
** inkscape:windows:build: GNU 13.2.0
** inkscape:windows:dist: Same as above
** inkscape:windows:dist: Same as above
* macOS:
* macOS:
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** inkscape:macos:x64: Apple Clang 13.0.0 (temporarily disabled since GTK4 port)
** inkscape:macos:x64: Apple Clang 13.0.0 (temporarily disabled since GTK4 port)


We strive to support latest Debian stable and latest Ubuntu LTS. However, we had to break that promise since the GTK4 port, which requires gtkmm4 >= 4.14:
We strive to support latest Debian stable and latest Ubuntu LTS.
{| class="wikitable"
{| class="wikitable"
|-
|-
! Distro                        || gcc    || clang  || gtkmm4
! Distro                        || gcc    || clang  || glib || glibmm || gtk4 || gtkmm4 || Can build?
|-
|-
| Debian 12 (Bookworm, stable)  || 12.2.0 || 15.0.6 || 4.8.3
| Debian 12 (Bookworm, stable)  || 12.2.0 || 15.0.6 || style="background: pink;" | 2.74.6 || style="background: pink;" | 2.74.0 || style="background: wheat;" | 4.8.3 || style="background: wheat;" | 4.8.3 || ❌
|-
|-
| Ubuntu 22.04 (Jammy Jellyfish) || 12.3.0 || 15.0.7 || Not packaged!
| Ubuntu 24.04 (Noble)           || 13.2.0 || 18.1.3 || 2.80.0 || 2.78.1 || 4.14.2 || style="background: wheat;" | 4.10.1 || ✅
|-
| Ubuntu 23.04 (Lunar)          || 13.1.0 || 16.0.0 || 4.10.1
|-
| Ubuntu 24.04 (Noble)          || 13.2.0 || 18.1.0 || 4.10.1 (???)
|}
|}


Ubuntu users therefore have the following options:
The build requires glibmm >= 2.78.1 and gtkmm4 >= 4.14. The build system will supply its own gtkmm4 if out-of-date. Therefore the build only currently works out of the box on Ubuntu 24.04.
 
* Wait for Ubuntu 24.04, expected around 25 April 2024.
* Upgrade to Ubuntu 24.04 now.
* Upgrade to Ubuntu 23.10 and build gtkmm4 from source, as is currently done by CI.
* ???


Deprecated items that we still use:
Deprecated items that we still use:
* warning: implicit capture of ‘this’ via ‘[=]’ is deprecated in C++20 [-Wdeprecated] https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0806r2.html
* warning: implicit capture of ‘this’ via ‘[=]’ is deprecated in C++20 [-Wdeprecated] https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0806r2.html
* warning: bitwise operation between different enumeration types ‘Box3D::Axis’ and ‘Box3D::FrontOrRear’ is deprecated [-Wdeprecated-enum-enum-conversion]
* warning: bitwise operation between different enumeration types ‘Box3D::Axis’ and ‘Box3D::FrontOrRear’ is deprecated [-Wdeprecated-enum-enum-conversion]

Latest revision as of 00:50, 10 July 2024

See also C++11, C++17, C++23.

Some things that will be interesting to use once C++20 is common:

Feature Since Can use? GCC Apple Clang Comment
std::span C++20 from 1.4 10 11.0.3 Handle buffers like standard library containers without risk of overflow.
std::format C++20 not yet 13 15.3 Better and more efficient formatting of strings. Text Formatting
std::lerp C++20 from 1.4 9 11.0.3 Linear interpolation. (ui/tools/pencil-tool.cpp)
std::bit_floor C++20 from 1.4 9/10 11.0.3/13.0.0 Compute floor(log2(x)). (helper/mathfns.h)
Concepts C++20 from 1.4? 6/10 12.0.0 Partial Safer templating. (ui/controller.h)
Coroutines C++20 not yet 10 10.0.1 Partial,
15.3 Full		 Simpler asynchronous code. (trace/trace.cpp)
std::make_unique_for_overwrite C++20 not yet 11 15.0.0 Don't zero arrays allocated using std::make_unique. (util/pool.cpp)
Ranges C++20 not yet ? (ui/dialog/swatches.cpp)
Structural templates C++20 from 1.4? Partial Allow instances of arbitrary literal classes as template parameters. (display/drawing.cpp)
Mathematical Constants C++20 10 12.0.5 Constants like std::numbers::pi.
Heterogenous lookup in std::unordered_map C++20 not yet Faster lookup, use of smart pointers as keys.
consteval static member functions C++20 not yet Guaranteed compile time evaluation of member functions (stronger than constexpr)

References:

As of 10 July 2024, the CI runners for the various supported platforms are

  • Linux:
    • appimage:linux: GNU 13.2.0 (building on Ubuntu 24.04)
    • inkscape:linux: Same as above
  • Windows
    • inkscape:windows:build: GNU 13.2.0
    • inkscape:windows:dist: Same as above
  • macOS:
    • inkscape::macos:arm: Apple Clang 15.0.0
    • inkscape:macos:x64: Apple Clang 13.0.0 (temporarily disabled since GTK4 port)

We strive to support latest Debian stable and latest Ubuntu LTS.

Distro gcc clang glib glibmm gtk4 gtkmm4 Can build?
Debian 12 (Bookworm, stable) 12.2.0 15.0.6 2.74.6 2.74.0 4.8.3 4.8.3 ❌
Ubuntu 24.04 (Noble) 13.2.0 18.1.3 2.80.0 2.78.1 4.14.2 4.10.1 ✅

The build requires glibmm >= 2.78.1 and gtkmm4 >= 4.14. The build system will supply its own gtkmm4 if out-of-date. Therefore the build only currently works out of the box on Ubuntu 24.04.

Deprecated items that we still use:

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