[CMake] Unable to find source files in different directory using target_sources(INTERFACE)

[Craig Scott]

Sorry, hit the send button prematurely. To achieve your desired goal of
creating a header only library as a target in Visual Studio, it somewhat
depends on what you want to do with that library. If you just want it to be
there so you can see the header in the IDE, then simply defining a dummy
custom target is one approach I've seen people use. E.g.

  add_custom_target(foo SOURCES foo.h)

If you want to actually link to the target so it can provide header search
path dependencies, then the approach you tried is probably the closest
(with the use of absolute paths as described in my previous email). As you
discovered though, it adds the header to the sources list of each project
linking against it, which it sounds like you want to avoid. An interface
library doesn't create build output on its own, so it doesn't make sense
for it to have its own list of sources. The only way sources make sense for
it is for those sources to be added to anything linking against it, which
is the behaviour you are seeing.





On Sun, Jul 10, 2016 at 10:04 AM, Craig Scott <craig.scott at crascit.com>
wrote:

> When using target_sources(), if you specify the source file(s) with a
> relative path, CMake does not convert that to an absolute path when storing
> it in the target's SOURCES property (that's my interpretation anyway). The
> end result is that the source you specify is going to be interpreted as
> being relative to the source directory the dependent target is defined in,
> not the directory where you called target_sources().  You can prevent the
> problem you described by ensuring the path for the source file(s) is always
> an absolute one. For example:
>
> target_sources(foo INTERFACE "${CMAKE_CURRENT_LIST_DIR}/foo.h")
>
> You may find the following blog article useful (it discusses the above
> problem and also other related material):
>
>
> https://crascit.com/2016/01/31/enhanced-source-file-handling-with-target_sources/
>
>
>
>
> On Sun, Jul 10, 2016 at 9:03 AM, Robert Dailey <rcdailey.lists at gmail.com>
> wrote:
>
>> I have the following:
>>
>> cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR)
>> project(foo)
>> add_library(foo INTERFACE)
>> target_sources(foo INTERFACE foo.h)
>> add_subdirectory(subdir)
>>
>> And inside subdir, I specify add_executable() and then
>> target_link_libraries(myexe foo).
>>
>> I get an error:
>>
>> Cannot find source file: foo.h
>>
>> I'm using CMake 3.6. What am I doing wrong here?
>>
>> My goal is to generate a header-only project in Visual Studio.
>> According to the documentation, what I'm trying to do won't give me
>> that. Instead, foo.h would exist in every project that links to it as
>> a dependency (that's what it seems like anyhow).
>>
>> Advice is appreciated.
>> --
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>
>
> --
> Craig Scott
> Melbourne, Australia
> http://crascit.com
>



-- 
Craig Scott
Melbourne, Australia
http://crascit.com
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