2.1.2. CMake build with library

Now, let’s extend Basic build with CMake to make a Library and use that for linking.

Updated CMakeLists.txt for that purpose would look like this.

CMAKE_MINIMUM_REQUIRED(VERSION 3.10)

PROJECT(greeting)

ADD_LIBRARY(
    greeting_en_lib
    greeting_en.c
)
ADD_LIBRARY(
    greeting_fr_lib
    greeting_fr.c
)
ADD_LIBRARY(
    greeting_es_lib
    greeting_es.c
)

ADD_EXECUTABLE(
    greeting_en
    main.c
)
TARGET_LINK_LIBRARIES(greeting_en greeting_en_lib)

ADD_EXECUTABLE(
    greeting_fr
    main.c
)
TARGET_LINK_LIBRARIES(greeting_fr greeting_fr_lib)

ADD_EXECUTABLE(
    greeting_es
    main.c
)
TARGET_LINK_LIBRARIES(greeting_es greeting_es_lib)

To compile that file with GCC, the command would be.

mkdir _build
cd _build
cmake .. -G "Unix Makefiles"

When the above command completes successfully, the compilation output would be:

-- The C compiler identification is GNU 11.3.0
-- The CXX compiler identification is GNU 11.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - 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: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/c6h6/data/p/book-tests/pgh_tech-sw-build-system/book/code/0210_cmake_lib/_build

Tree structure of generated file would be:

_build/
|-- CMakeCache.txt
|-- cmake_install.cmake
|-- greeting_en*
|-- greeting_es*
|-- greeting_fr*
|-- libgreeting_en_lib.a
|-- libgreeting_es_lib.a
|-- libgreeting_fr_lib.a
|-- Makefile
`-- CMakeFiles/
    |-- cmake.check_cache
    |-- CMakeDirectoryInformation.cmake
    |-- CMakeOutput.log
    |-- Makefile2
    |-- Makefile.cmake
    |-- progress.marks
    |-- TargetDirectories.txt
    |-- 3.22.1/
    |   |-- CMakeCCompiler.cmake
    |   |-- CMakeCXXCompiler.cmake
    |   |-- CMakeDetermineCompilerABI_C.bin*
    |   |-- CMakeDetermineCompilerABI_CXX.bin*
    |   |-- CMakeSystem.cmake
    |   |-- CompilerIdC/
    |   |   |-- a.out*
    |   |   |-- CMakeCCompilerId.c
    |   |   `-- tmp/
    |   `-- CompilerIdCXX/
    |       |-- a.out*
    |       |-- CMakeCXXCompilerId.cpp
    |       `-- tmp/
    |-- CMakeTmp/
    |-- greeting_en.dir/
    |   |-- build.make
    |   |-- cmake_clean.cmake
    |   |-- compiler_depend.make
    |   |-- compiler_depend.ts
    |   |-- DependInfo.cmake
    |   |-- depend.make
    |   |-- flags.make
    |   |-- link.txt
    |   |-- main.c.o
    |   |-- main.c.o.d
    |   `-- progress.make
    |-- greeting_en_lib.dir/
    |   |-- build.make
    |   |-- cmake_clean.cmake
    |   |-- cmake_clean_target.cmake
    |   |-- compiler_depend.make
    |   |-- compiler_depend.ts
    |   |-- DependInfo.cmake
    |   |-- depend.make
    |   |-- flags.make
    |   |-- greeting_en.c.o
    |   |-- greeting_en.c.o.d
    |   |-- link.txt
    |   `-- progress.make
    |-- greeting_es.dir/
    |   |-- build.make
    |   |-- cmake_clean.cmake
    |   |-- compiler_depend.make
    |   |-- compiler_depend.ts
    |   |-- DependInfo.cmake
    |   |-- depend.make
    |   |-- flags.make
    |   |-- link.txt
    |   |-- main.c.o
    |   |-- main.c.o.d
    |   `-- progress.make
    |-- greeting_es_lib.dir/
    |   |-- build.make
    |   |-- cmake_clean.cmake
    |   |-- cmake_clean_target.cmake
    |   |-- compiler_depend.make
    |   |-- compiler_depend.ts
    |   |-- DependInfo.cmake
    |   |-- depend.make
    |   |-- flags.make
    |   |-- greeting_es.c.o
    |   |-- greeting_es.c.o.d
    |   |-- link.txt
    |   `-- progress.make
    |-- greeting_fr.dir/
    |   |-- build.make
    |   |-- cmake_clean.cmake
    |   |-- compiler_depend.make
    |   |-- compiler_depend.ts
    |   |-- DependInfo.cmake
    |   |-- depend.make
    |   |-- flags.make
    |   |-- link.txt
    |   |-- main.c.o
    |   |-- main.c.o.d
    |   `-- progress.make
    `-- greeting_fr_lib.dir/
        |-- build.make
        |-- cmake_clean.cmake
        |-- cmake_clean_target.cmake
        |-- compiler_depend.make
        |-- compiler_depend.ts
        |-- DependInfo.cmake
        |-- depend.make
        |-- flags.make
        |-- greeting_fr.c.o
        |-- greeting_fr.c.o.d
        |-- link.txt
        `-- progress.make

13 directories, 94 files

If we just diff this with Basic build with CMake, here are the changes

6a7,9
> |-- libgreeting_en_lib.a
> |-- libgreeting_es_lib.a
> |-- libgreeting_fr_lib.a
38a42,54
>     |   |-- link.txt
>     |   |-- main.c.o
>     |   |-- main.c.o.d
>     |   `-- progress.make
>     |-- greeting_en_lib.dir/
>     |   |-- build.make
>     |   |-- cmake_clean.cmake
>     |   |-- cmake_clean_target.cmake
>     |   |-- compiler_depend.make
>     |   |-- compiler_depend.ts
>     |   |-- DependInfo.cmake
>     |   |-- depend.make
>     |   |-- flags.make
41a58,67
>     |   `-- progress.make
>     |-- greeting_es.dir/
>     |   |-- build.make
>     |   |-- cmake_clean.cmake
>     |   |-- compiler_depend.make
>     |   |-- compiler_depend.ts
>     |   |-- DependInfo.cmake
>     |   |-- depend.make
>     |   |-- flags.make
>     |   |-- link.txt
45c71
<     |-- greeting_es.dir/
---
>     |-- greeting_es_lib.dir/
47a74
>     |   |-- cmake_clean_target.cmake
55a83,92
>     |   `-- progress.make
>     |-- greeting_fr.dir/
>     |   |-- build.make
>     |   |-- cmake_clean.cmake
>     |   |-- compiler_depend.make
>     |   |-- compiler_depend.ts
>     |   |-- DependInfo.cmake
>     |   |-- depend.make
>     |   |-- flags.make
>     |   |-- link.txt
59c96
<     `-- greeting_fr.dir/
---
>     `-- greeting_fr_lib.dir/
61a99
>         |-- cmake_clean_target.cmake
70,71d107
<         |-- main.c.o
<         |-- main.c.o.d
74c110
< 10 directories, 61 files
---
> 13 directories, 94 files