[librabbitmq] include path missing

[anders-wind]

---

Is your feature request related to a problem? Please describe.
When adding librabbitmq as a dependency the target does not set a target_include_directories. So while the header is located in the build/vcpkg_installed/x64-linux/include/amqp.h we still get a "cannot find the specified header" even after find_package(rabbitmq-c CONFIG REQUIRED) and adding rabbitmq::rabbitmq-static to target_link_libraries.

My temporary solution has been to add "$<BUILD_INTERFACE:${PACKAGE_PREFIX_DIR}/include>" to my own target_include_directories but it feels a bit hacky.

Proposed solution
Add a patch to the library which adds target_include_directories in a proper maner.

[FrankXie05]

@anders-wind Thanks for posting this issue, I didn't reproduce your problem locally, can you provide an example of your project? Here is my project example and build log：

PS E:\test\build> cmake.exe .. -DCMAKE_TOOLCHAIN_FILE=E:/vcpkg/scripts/buildsystems/vcpkg.cmake                                                                 
-- Building for: Visual Studio 16 2019                                                                                  
-- Running vcpkg install                                                                                                
Detecting compiler hash for triplet x64-windows...                                                                      
The following packages will be built and installed:                                                                         
librabbitmq[core]:x64-windows -> 0.11.0                                                                               
* openssl[core]:x64-windows -> 1.1.1n#1                                                                                 
* vcpkg-cmake[core]:x64-windows -> 2022-02-14                                                                           
* vcpkg-cmake-config[core]:x64-windows -> 2022-02-06                                                                  
Additional packages (*) will be modified to complete this operation.                                                    
Restored 4 packages from C:\Users\test\AppData\Local\vcpkg\archives in 791.2 ms. Use --debug to see more details. 
Starting package 1/4: vcpkg-cmake-config:x64-windows                                                                    
Installing package vcpkg-cmake-config[core]:x64-windows...                                                              
Elapsed time for package vcpkg-cmake-config:x64-windows: 10.54 ms                                                       
Starting package 2/4: vcpkg-cmake:x64-windows                                                                           
Installing package vcpkg-cmake[core]:x64-windows...                                                                     
Elapsed time for package vcpkg-cmake:x64-windows: 51.29 ms                                                              
Starting package 3/4: openssl:x64-windows                                                                               
Installing package openssl[core]:x64-windows...                                                                         
Elapsed time for package openssl:x64-windows: 890.1 ms                                                                  
Starting package 4/4: librabbitmq:x64-windows                                                                           
Installing package librabbitmq[core]:x64-windows...                                                                     
Elapsed time for package librabbitmq:x64-windows: 135.3 ms                                                              
                                                                                                                        
Total elapsed time: 6.349 s                                                                                               

The package librabbitmq provides CMake targets:                                                                           
                                                                                                                          
	find_package(rabbitmq-c CONFIG REQUIRED)                                                                                
	target_link_libraries(main PRIVATE rabbitmq::rabbitmq rabbitmq::rabbitmq-static)   
	
-- Running vcpkg install - done                                                                                         
-- Selecting Windows SDK version 10.0.22000.0 to target Windows 10.0.19044.                                             
-- The C compiler identification is MSVC 19.29.30141.0                                                                 
-- The CXX compiler identification is MSVC 19.29.30141.0                                                                
-- Detecting C compiler ABI info                                                                                        
-- Detecting C compiler ABI info - done                                                                                 
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/VC/Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe - skipped      
-- Detecting C compile features                                                                                         
-- Detecting C compile features - done                                                                                  
-- Detecting CXX compiler ABI info                                                                                      
-- Detecting CXX compiler ABI info - done                                                                               
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2019/Enterprise/VC/Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe - skipped      
-- Detecting CXX compile features                                                                                       
-- Detecting CXX compile features - done                                                                                
-- Configuring done                                                                                                     
-- Generating done                                                                                                      
-- Build files have been written to: E:/test/build                                                                      
PS E:\test\build> 

test.zip

[anders-wind]

Hi @FrankXie05, thanks for taking a look at my problem :) I'm going on vacation and have not had time to try your example. Though I see that youre including #include "rabbitmq-c.h" and not include <amqp.h> It might be that the library never intended that file to be included, but we are relying on a third party project which does include it.
I will try out your example when I get back :)

[FrankXie05]

@anders-wind I reproduced it，and I found that there is a way upstream to export the include definition file(https://github.com/alanxz/rabbitmq-c/blob/26ecf6d3012be81f5dfb8a2d822c722e916a86cb/librabbitmq/CMakeLists.txt#L72), but it doesn't link in the top-level CMakeLists.txt , it might be an upstream bug, you can submit an issue upstream to fix it. :)