# Trying to make prebuilt binary library dependency transitive - but how?

**URL:** <https://discuss.gradle.org/t/trying-to-make-prebuilt-binary-library-dependency-transitive-but-how/32303>\
**Category:** Help/Discuss\
**Created:** [July 5, 2019, 6:15am UTC](https://discuss.gradle.org/t/trying-to-make-prebuilt-binary-library-dependency-transitive-but-how/32303 "2019-07-05T06:15:45Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![darkeye](https://sea1.discourse-cdn.com/gradle/user_avatar/discuss.gradle.org/darkeye/32/405_2.png) [@darkeye](https://discuss.gradle.org/u/darkeye)\
**Post date:** [July 5, 2019, 6:15am UTC](https://discuss.gradle.org/t/trying-to-make-prebuilt-binary-library-dependency-transitive-but-how/32303/1 "2019-07-05T06:15:45Z")

</div>

Hi,

I’m trying to include a prebuilt library dependency into my project, based on the prebuilt-binaries example in native-samples: [https://github.com/gradle/native-samples/tree/master/cpp/prebuilt-binaries](https://github.com/gradle/native-samples/tree/master/cpp/prebuilt-binaries)

here is my take on the topic: [https://github.com/akosmaroy/gradle-playground/tree/master/external-lib-sample](https://github.com/akosmaroy/gradle-playground/tree/master/external-lib-sample)

but it fails, as the external library binary files are not ‘carried over’ through the dependency chain:

```
git clone https://github.com/akosmaroy/gradle-playground.git
cd gradle-payground/external-lib-sample
cd external
./gradlew build
../theapp
./gradlew build

```

and I’d expect this to work. but this is what I get:

```
cd external/
$ ./gradlew build

BUILD SUCCESSFUL in 614ms
2 actionable tasks: 2 executed

$ cd ../theapp/
$ ./gradlew build

> Task :myapp:linkDebug FAILED
/usr/bin/ld: warning: libexternal.so, needed by /home/akos/src/gradle-playground/external-lib-sample/theapp/mylibrary/build/lib/main/debug/libmylibrary.so, not found (try using -rpath or -rpath-link)
/usr/bin/ld: /home/akos/src/gradle-playground/external-lib-sample/theapp/mylibrary/build/lib/main/debug/libmylibrary.so: undefined reference to `getExternalHello[abi:cxx11]()'
collect2: error: ld returned 1 exit status

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':myapp:linkDebug'.
> A build operation failed.
      Linker failed while linking myapp.
  See the complete log at: file:///home/akos/src/gradle-playground/external-lib-sample/theapp/myapp/build/tmp/linkDebug/output.txt
   > Linker failed while linking myapp.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 690ms
4 actionable tasks: 4 executed

```

looking at the directory structure, indeed, the external library file, libexternal.so, is not ‘carried over’ to libmylibrary:

```
$ tree .
.
├── external
│ ├── build
│ │ ├── lib
│ │ │ └── main
│ │ │ └── debug
│ │ │ └── libexternal.so
│ │ ├── obj
│ │ │ └── main
│ │ │ └── debug
│ │ │ └── 7o4bm6kwb4cvb14rrd957us1j
│ │ │ └── external.o
│ │ └── tmp
│ │ ├── compileDebugCpp
│ │ │ ├── options.txt
│ │ │ └── output.txt
│ │ └── linkDebug
│ │ ├── options.txt
│ │ └── output.txt
│ ├── build.gradle
│ ├── gradle
│ │ └── wrapper
│ │ ├── gradle-wrapper.jar
│ │ └── gradle-wrapper.properties
│ ├── gradlew
│ ├── gradlew.bat
│ └── src
│ └── main
│ ├── cpp
│ │ └── external.cpp
│ ├── include
│ └── public
│ └── external.h
└── theapp
    ├── gradle
    │ └── wrapper
    │ ├── gradle-wrapper.jar
    │ └── gradle-wrapper.properties
    ├── gradlew
    ├── gradlew.bat
    ├── myapp
    │ ├── build
    │ │ ├── exe
    │ │ │ └── main
    │ │ │ └── debug
    │ │ ├── obj
    │ │ │ └── main
    │ │ │ └── debug
    │ │ │ └── c0rn65lkroj8p4fvz0qgmzzjr
    │ │ │ └── app.o
    │ │ └── tmp
    │ │ ├── compileDebugCpp
    │ │ │ ├── options.txt
    │ │ │ └── output.txt
    │ │ └── linkDebug
    │ │ ├── options.txt
    │ │ └── output.txt
    │ ├── build.gradle
    │ └── src
    │ └── main
    │ ├── cpp
    │ │ └── app.cpp
    │ └── headers
    │ └── app.h
    ├── mylibrary
    │ ├── build
    │ │ ├── lib
    │ │ │ └── main
    │ │ │ └── debug
    │ │ │ └── libmylibrary.so
    │ │ ├── obj
    │ │ │ └── main
    │ │ │ └── debug
    │ │ │ └── 9b7fb0ryo4gvfllswhexp447v
    │ │ │ └── mylibrary.o
    │ │ └── tmp
    │ │ ├── compileDebugCpp
    │ │ │ ├── options.txt
    │ │ │ └── output.txt
    │ │ └── linkDebug
    │ │ ├── options.txt
    │ │ └── output.txt
    │ ├── build.gradle
    │ └── src
    │ └── main
    │ ├── cpp
    │ │ └── mylibrary.cpp
    │ ├── include
    │ └── public
    │ └── mylibrary.h
    └── settings.gradle

55 directories, 35 files

```

if I add the directory holding libexternal.so to LD\_LIBRARY\_PATH, it will work:

```
$ export LD_LIBRARY_PATH=/home/akos/src/gradle-playground/external-lib-sample/external/build/lib/main/debug
$ cd theapp
$ ./gradelw build

BUILD SUCCESSFUL in 675ms
5 actionable tasks: 5 executed

```

interestingly, the dependency manager ‘carries over’ libmylibrary.so during the build process to theapp:

```
$ ls -l myapp/build/install/main/debug/lib/
total 132
-rwxr-xr-x 1 akos akos 61312 Jul 5 08:12 libmylibrary.so
-rwxr-xr-x 1 akos akos 70552 Jul 5 08:12 myapp

```

but libexternal.so is not ‘carried over’ in a similar fashion.

how would I achieve that libexternal.so is also ‘carried over’, so that the build completes successfully?

Akos