Adding to existing project

[flpDiskJ]

Hello.

I would like to add this library to a music tracker I'm working on. Following the docs I'm confused on how I would add this lib to my per-existing cmake environment.

When I add the include statement to my code

#include <libremidi/libremidi-c.h>

It says it cannot be found..

I assume I need to add something to my cmakelists.txt but I'm not sure what exactly.

[jcelerier]

hello ! how does your CMakeLists.txt look like ?
The simplest way is to use add_subdirectory and then link libremidi to your app:

project(your_project)

# load dependencies
add_subdirectory(3rdparty/libremidi) # example folder

# create your app
add_executable(your_tracker foo.cpp bar.cpp main.cpp)
target_link_libraries(your_tracker PRIVATE libremidi)

[flpDiskJ]

This worked!
Thanks for the help :D

[jcelerier]

Added some documentation here: https://celtera.github.io/libremidi/cmake.html

[flpDiskJ]

Awesome.

I got it to compile with the include statement but I tried adding some of the example code and it's giving the following errors

error: ‘libremidi’ has not been declared
 1755 |         for (auto& api : libremidi::available_apis())
      |                          ^~~~~~~~~
/home/jake/code/c/octopus/src/headers/tracker.cpp:1757:36: error: ‘libremidi’ has not been declared
 1757 |             string_view api_name = libremidi::get_api_display_name(api);
      |                                    ^~~~~~~~~
/home/jake/code/c/octopus/src/headers/tracker.cpp:1763:13: error: ‘libremidi’ has not been declared
 1763 |             libremidi::observer midi{
      |             ^~~~~~~~~
/home/jake/code/c/octopus/src/headers/tracker.cpp:1768:28: error: ‘midi’ was not declared in this scope
 1768 |               auto ports = midi.get_input_ports();
      |                            ^~~~
/home/jake/code/c/octopus/src/headers/tracker.cpp:1777:28: error: ‘midi’ was not declared in this scope
 1777 |               auto ports = midi.get_output_ports();
      |                            ^~~~
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-c99-extensions’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-gnu-statement-expression-from-macro-expansion’ may have been intended to silence earlier diagnostics
make[2]: *** [CMakeFiles/octopus.dir/build.make:90: CMakeFiles/octopus.dir/src/headers/tracker.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:117: CMakeFiles/octopus.dir/all] Error 2
make: *** [Makefile:156: all] Error 2

[jcelerier]

You need to include the C++ api:

#include <libremidi/libremidi.hpp>

and not

#include <libremidi/libremidi-c.h>

which is the C api

[flpDiskJ]

Switching to the c++ include gives a boatload of errors :/

In file included from /home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:4,
                 from /home/jake/code/c/octopus/src/include/libremidi/include/libremidi/defaults.hpp:4,
                 from /home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:61,
                 from /home/jake/code/c/octopus/src/headers/global.h:12,
                 from /home/jake/code/c/octopus/src/headers/tracker.h:3,
                 from /home/jake/code/c/octopus/src/main.cpp:5:
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/message.hpp:75:17: error: ‘span’ in namespace ‘std’ does not name a template type
   75 |   operator std::span<const unsigned char>() const noexcept { return {bytes.data(), bytes.size()}; }
      |                 ^~~~
In file included from /home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:5:
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/ump.hpp:18:3: error: ‘constexpr’ destructors only available with ‘-std=c++20’ or ‘-std=gnu++20’
   18 |   constexpr ~ump() = default;
      |   ^~~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:43:46: error: ‘span’ is not a member of ‘std’
   43 | using raw_callback = std::function<void(std::span<const uint8_t>, timestamp)>;
      |                                              ^~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:43:76: error: expression list treated as compound expression in functional cast [-fpermissive]
   43 | using raw_callback = std::function<void(std::span<const uint8_t>, timestamp)>;
      |                                                                            ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:43:77: error: template argument 1 is invalid
   43 | using raw_callback = std::function<void(std::span<const uint8_t>, timestamp)>;
      |                                                                             ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:53:3: error: ‘raw_callback’ does not name a type; did you mean ‘message_callback’?
   53 |   raw_callback on_raw_data{};
      |   ^~~~~~~~~~~~
      |   message_callback
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:87:50: error: ‘span’ is not a member of ‘std’
   87 | using raw_ump_callback = std::function<void(std::span<const uint32_t>, timestamp)>;
      |                                                  ^~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:87:81: error: expression list treated as compound expression in functional cast [-fpermissive]
   87 | using raw_ump_callback = std::function<void(std::span<const uint32_t>, timestamp)>;
      |                                                                                 ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:87:82: error: template argument 1 is invalid
   87 | using raw_ump_callback = std::function<void(std::span<const uint32_t>, timestamp)>;
      |                                                                                  ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/input_configuration.hpp:96:3: error: ‘raw_ump_callback’ does not name a type; did you mean ‘ump_callback’?
   96 |   raw_ump_callback on_raw_data{};
      |   ^~~~~~~~~~~~~~~~
      |   ump_callback
In file included from /home/jake/code/c/octopus/src/include/libremidi/include/libremidi/defaults.hpp:5:
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:42:8: error: defaulted ‘bool libremidi::port_information::operator==(const libremidi::port_information&) const’ only available with ‘-std=c++20’ or ‘-std=gnu++20’
   42 |   bool operator==(const port_information& other) const noexcept = default;
      |        ^~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:43:8: error: ‘strong_ordering’ in namespace ‘std’ does not name a type
   43 |   std::strong_ordering operator<=>(const port_information& other) const noexcept = default;
      |        ^~~~~~~~~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:43:3: note: ‘std::strong_ordering’ is only available from C++20 onwards
   43 |   std::strong_ordering operator<=>(const port_information& other) const noexcept = default;
      |   ^~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:48:8: error: defaulted ‘bool libremidi::input_port::operator==(const libremidi::input_port&) const’ only available with ‘-std=c++20’ or ‘-std=gnu++20’
   48 |   bool operator==(const input_port& other) const noexcept = default;
      |        ^~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:49:8: error: ‘strong_ordering’ in namespace ‘std’ does not name a type
   49 |   std::strong_ordering operator<=>(const input_port& other) const noexcept = default;
      |        ^~~~~~~~~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:49:3: note: ‘std::strong_ordering’ is only available from C++20 onwards
   49 |   std::strong_ordering operator<=>(const input_port& other) const noexcept = default;
      |   ^~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:53:8: error: defaulted ‘bool libremidi::output_port::operator==(const libremidi::output_port&) const’ only available with ‘-std=c++20’ or ‘-std=gnu++20’
   53 |   bool operator==(const output_port& other) const noexcept = default;
      |        ^~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:54:8: error: ‘strong_ordering’ in namespace ‘std’ does not name a type
   54 |   std::strong_ordering operator<=>(const output_port& other) const noexcept = default;
      |        ^~~~~~~~~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/observer_configuration.hpp:54:3: note: ‘std::strong_ordering’ is only available from C++20 onwards
   54 |   std::strong_ordering operator<=>(const output_port& other) const noexcept = default;
      |   ^~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:216:28: error: ‘std::span’ has not been declared
  216 |   stdx::error send_message(std::span<const unsigned char>) const;
      |                            ^~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:216:37: error: expected ‘,’ or ‘...’ before ‘<’ token
  216 |   stdx::error send_message(std::span<const unsigned char>) const;
      |                                     ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:235:24: error: ‘std::span’ has not been declared
  235 |   stdx::error send_ump(std::span<const uint32_t>) const;
      |                        ^~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:235:33: error: expected ‘,’ or ‘...’ before ‘<’ token
  235 |   stdx::error send_ump(std::span<const uint32_t>) const;
      |                                 ^
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:241:15: error: ‘stdx::error libremidi::midi_out::send_ump(int32_t) const’ cannot be overloaded with ‘stdx::error libremidi::midi_out::send_ump(int) const’
  241 |   stdx::error send_ump(int32_t b0) const;
      |               ^~~~~~~~
/home/jake/code/c/octopus/src/include/libremidi/include/libremidi/libremidi.hpp:235:15: note: previous declaration ‘stdx::error libremidi::midi_out::send_ump(int) const’
  235 |   stdx::error send_ump(std::span<const uint32_t>) const;
      |               ^~~~~~~~
cc1plus: note: unrecognized command-line option ‘-Wno-c99-extensions’ may have been intended to silence earlier diagnostics
cc1plus: note: unrecognized command-line option ‘-Wno-gnu-statement-expression-from-macro-expansion’ may have been intended to silence earlier diagnostics
make[2]: *** [CMakeFiles/octopus.dir/build.make:76: CMakeFiles/octopus.dir/src/main.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:117: CMakeFiles/octopus.dir/all] Error 2
make: *** [Makefile:156: all] Error 2

[jcelerier]

You need to make your project C++20 as libremidi requires it. Here it seems that your compiler is in c++11 / 14 mode as it does not know about std::span (c++17)

target_compile_features(your_app PUBLIC cxx_std_20)