I'm using GCC for Renesas with Renesas's E2 Studio IDE (v.6.2.0). Not that it should matter, but I've also used Applilet3 (v.3.08.01.05) to generate board support files and peripheral drivers.

When I attempt to build, I get the following errors...

'Invoking Linker'
rl78-elf-gcc (......object files and flags.......)
./src/r_main.o: In function `main':

<path_to_git_repo_dir>\src\<project_name>\HardwareDebug/../src/r_main.c:86: undefined reference to `_common_lib_a_init'
<path_to_git_repo_dir>\src\<project_name>\HardwareDebug/../src/r_main.c:89: undefined reference to `_common_lib_b_init'

collect2.exe: error: ld returned 1 exit status
makefile:67: recipe for target 'my_project.elf' failed
make: *** [my_project.elf] Error 1

Project Setup

I have some source code shared between projects in a "lib" folder. In main() I call some initialize functions for these "libraries", as you can see from the errors. I don't understand why the compile process works and yet this fails.

My source tree layout looks like this...

git-repo-dir/
    .git/
    doc/
    lib/
        my_lib_a/
            common_lib_a.h
            common_lib_a.c
        my_lib_b/
            common_lib_b.h
            common_lib_b.c
    src/
        my_project/
            .cproj
            .project
            applilet3_config.cgp
            src/
            generate/

I added the library source code to my E2 Studio project by...

• Right-clicking on the project name in E2's "Project Explorer" pane
• Clicking Import and select File System
• Browse to get-repo-dir and select (single-click) the lib folder
• Check the box on the left pane to include all files in lib
• Ensure "Create top-level folder" is selected
• Click "Advanced"
• Check the box for "Create links in workspace" and "Create virtual folders" and "Create link locations relative to:" is PROJECT_LOC
• Finish

Then I add the include paths for the libraries to the build settings...

• Right-clicking on the project name in E2's "Project Explorer" pane
• Select "Properties"
• Select C/C++ General > Paths and Symbols
• Ensure configuration is the current/active one
• Select the "GNU C" language
• Click "Add" to add the following
  • "${ProjDirPath}/../../lib/my_lib_a"
  • "${ProjDirPath}/../../lib/my_lib_b"
• Apply
• Verify these paths are visible in C/C++ Build > Settings > Compiler > Includes

So in E2 Studio, the Project Explorer shows..

Archives/           (a virtual folder)
Includes/           (a virtual folder/list)
src/
generate/
lib/                (the virtual lib folder I added)
    my_lib_a/
    my_lib_b/

Any ideas why I'm getting a linker error?

I eventually noticed that the build log didn't contain any C files from the lib/ folder.

The solution was simple. In E2 Studio, in the Project Explorer pane, I dragged the lib/ folder in to (on top of) the src/ folder.

Now the structure in Project Explorer looks like this:

Archives/           (a virtual folder)
Includes/           (a virtual folder/list)
src/
    lib/            (the virtual lib folder I added)
        my_lib_a/
        my_lib_b/
generate/

Evidently E2 Studio does not put source code that's outside of the src/ directory in the autogenerated make file. Or maybe there's some setting I missed. Nonetheless, since the C code wasn't compiled, there was no object file to link against, hence the linker error.