Prevent Circular Data Dependencies with One-Pass or Single-Pass Linkers

Symptom: During a software build, a build error occurs; variables don't resolve correctly.

If your toolchain uses a one-pass or single-pass linker, prevent circular data dependencies by adding the StartLibraryGroup and EndLibraryGroup linker directives to the toolchain definition file. The build process applies the grouping directives to model reference libraries $(MODELREF_LIBS) and user libraries $(LIBS).

For example, if the linker is like GNU gcc, then the directives are '-Wl,--start-group' and '-Wl,--end-group', as shown here:

% ------------------------------
% Linker
% ------------------------------

tool = tc.getBuildTool('Linker');

tool.setName(           'GNU Linker');
tool.setCommand(        'gcc');
tool.setPath(           '');

tool.setDirective(      'Library',                           '-l');
tool.setDirective(      'LibrarySearchPath',                 '-L');
tool.setDirective(      'OutputFlag',                        '-o');
tool.setDirective(      'Debug',                             '-g');
tool.addDirective(      'StartLibraryGroup',  '-Wl,--start-group');
tool.addDirective(      'EndLibraryGroup',      '-Wl,--end-group');

tool.setFileExtension(  'Executable',       '');
tool.setFileExtension(  'Shared Library',   '.so');