From 0ec60c03cbe87cdbfb9fb199c7536fdcbc0a94b8 Mon Sep 17 00:00:00 2001
From: Ihor Dutchak <ihor.youw@gmail.com>
Date: Fri, 24 Sep 2021 18:58:01 +0300
Subject: [PATCH] Add <root>/libusb to includes for in-tree build

Otherwise it is impossible to `#include <hidapi_libusb.h>`,
when HIDAPI is added directly as a subdirectory of a CMake project.
---
 libusb/CMakeLists.txt | 5 +++--
 src/CMakeLists.txt    | 3 +++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/libusb/CMakeLists.txt b/libusb/CMakeLists.txt
index c7873de..f4392d7 100644
--- a/libusb/CMakeLists.txt
+++ b/libusb/CMakeLists.txt
@@ -1,9 +1,10 @@
 cmake_minimum_required(VERSION 3.6.3 FATAL_ERROR)
 
+list(APPEND HIDAPI_PUBLIC_HEADERS "hidapi_libusb.h")
+
 add_library(hidapi_libusb
     ${HIDAPI_PUBLIC_HEADERS}
     hid.c
-    hidapi_libusb.h
 )
 target_link_libraries(hidapi_libusb PUBLIC hidapi_include)
 
@@ -24,7 +25,7 @@ set_target_properties(hidapi_libusb
         OUTPUT_NAME "hidapi-libusb"
         VERSION ${PROJECT_VERSION}
         SOVERSION ${PROJECT_VERSION_MAJOR}
-        PUBLIC_HEADER "${HIDAPI_PUBLIC_HEADERS};hidapi_libusb.h"
+        PUBLIC_HEADER "${HIDAPI_PUBLIC_HEADERS}"
 )
 
 # compatibility with find_package()
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ae59369..8f454e5 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -125,6 +125,9 @@ else()
         set(HIDAPI_WITH_LIBUSB ON)
     endif()
     if(HIDAPI_WITH_LIBUSB)
+        target_include_directories(hidapi_include INTERFACE
+            "$<BUILD_INTERFACE:${PROJECT_ROOT}/libusb>"
+        )
         add_subdirectory("${PROJECT_ROOT}/libusb" libusb)
         list(APPEND EXPORT_COMPONENTS libusb)
         if(NOT EXPORT_ALIAS)