Upstream PR: https://github.com/milkytracker/MilkyTracker/pull/423

From fe29c2be199642feda3254a89280a72ec7ebf7be Mon Sep 17 00:00:00 2001
From: Matthew White <mehw.is.me@proton.me>
Date: Sun, 1 Nov 2026 14:08:24 +0000
Subject: [PATCH] Fix incomplete type error for class RtMidiIn

This error was found while compiling MilkyTracker v1.05.01 on Gentoo.

It can be fixed by replacing the forward declaration of RtMidiIn with
its definition from RtMidi.h header.

Additionally, mark RTMIDI_INCLUDE_DIRS as PUBLIC, so that the correct
include directory (e.g. '/usr/include/rtmidi' on Gentoo) is available
when compiling.

Buglink: https://bugs.gentoo.org/985348
Signed-off-by: Matthew White <mehw.is.me@proton.me>
---
 src/midi/CMakeLists.txt                 | 1 +
 src/midi/posix/MidiReceiver_pthread.cpp | 1 -
 src/midi/posix/MidiReceiver_pthread.h   | 3 +--
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/midi/CMakeLists.txt b/src/midi/CMakeLists.txt
index ceb850e..d737c84 100644
--- a/src/midi/CMakeLists.txt
+++ b/src/midi/CMakeLists.txt
@@ -111,6 +111,7 @@ else()
     target_include_directories(midi
         PRIVATE
             ${CMAKE_CURRENT_SOURCE_DIR}/../ppui/osinterface/posix
+        PUBLIC
             ${RTMIDI_INCLUDE_DIRS}
     )
 
diff --git a/src/midi/posix/MidiReceiver_pthread.cpp b/src/midi/posix/MidiReceiver_pthread.cpp
index 43a5148..f9e7f50 100644
--- a/src/midi/posix/MidiReceiver_pthread.cpp
+++ b/src/midi/posix/MidiReceiver_pthread.cpp
@@ -31,7 +31,6 @@
 #include "MidiReceiver_pthread.h"
 #include "Tracker.h"
 #include "PPMutex.h"
-#include "RtMidi.h"
 #include "PPSystem.h"
 #include <iostream>
 #include "MidiTools.h"
diff --git a/src/midi/posix/MidiReceiver_pthread.h b/src/midi/posix/MidiReceiver_pthread.h
index 23b7aba..a8e2abe 100644
--- a/src/midi/posix/MidiReceiver_pthread.h
+++ b/src/midi/posix/MidiReceiver_pthread.h
@@ -32,8 +32,7 @@
 #define __MIDIRECEIVER_H__
 
 #include <vector>
-
-class RtMidiIn;
+#include "RtMidi.h"
 
 class MidiReceiver
 {
-- 
2.56.0