Merge pull request #2301 from nlohmann/regression2281

Add test with multiple translation units

test/cmake_target_include_directories/project/Bar.cpp

+#include "Bar.hpp"
+
+class Bar;

test/cmake_target_include_directories/project/Bar.hpp

+#include <nlohmann/json.hpp>
+#include "Foo.hpp"
+
+class Bar : public Foo{};

test/cmake_target_include_directories/project/CMakeLists.txt

@@ -9,3 +9,13 @@ set_target_properties(with_private_target PROPERTIES CXX_STANDARD 11)
 add_executable(with_private_system_target main.cpp)
 target_include_directories(with_private_system_target PRIVATE SYSTEM ${nlohmann_json_source}/include)
 set_target_properties(with_private_system_target PROPERTIES CXX_STANDARD 11)
+
+# regression from https://github.com/nlohmann/json/discussions/2281
+add_library(Foo STATIC Foo.cpp Bar.cpp)
+target_include_directories(Foo PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} ${nlohmann_json_source}/include)
+set_target_properties(Foo PROPERTIES CXX_STANDARD 11)
+
+add_library(Bar STATIC Bar.cpp)
+target_link_libraries(Bar PRIVATE Foo)
+target_include_directories(Bar PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} ${nlohmann_json_source}/include)
+set_target_properties(Bar PROPERTIES CXX_STANDARD 11)

test/cmake_target_include_directories/project/Foo.cpp

+#include "Foo.hpp"
+
+class Foo;

test/cmake_target_include_directories/project/Foo.hpp

+#pragma once
+#include <nlohmann/json.hpp>
+
+class Foo{};