title: Build library archive with undefined references
body: <p>A colleague of mine told me yesterday that building libfoo.a doesn't require all it's functions to be defined, as long as they will be if you are building an executable that links to it AND that defines that missing reference..</p>
  
  <p>He said that archives are only a collection of object files with indexing, and since object files can be build with undefined references, so can archives..</p>
  
  <p>Is this true ? If so, does this imply that reference resolving is ONLY performed during the linking stage (ie never at compilation or archiving) ?</p>
  
  <p>Thanks a lot.. compiler is gcc by the way, language is c/c++</p>