Fix issue windelbouwman#102 by better selecting the library objectfil…

…e to merge: select only objectfiles defining globally at least one yet unresolved symbol

ppci/binutils/linker.py

@@ -390,7 +390,7 @@ def add_missing_symbols_from_libraries(self, libraries):
             for library in libraries:
                 self.logger.debug("scanning library for symbols %s", library)
                 for obj in library:
-                    has_sym = any(map(obj.has_symbol, undefined_symbols))
+                    has_sym = any(map(obj.is_defined_global, undefined_symbols))
                     if has_sym:
                         self.logger.debug(
                             "Using object file %s from library", obj

ppci/binutils/objectfile.py

@@ -58,6 +58,11 @@ def defined(self):
     def is_global(self):
         return self.binding == "global"
 
+    @property
+    def is_defined_global(self):
+        """ Test if the symbol in defined and global. """
+        return self.value is not None and self.binding == "global"
+
     @property
     def is_function(self):
         """ Test if this symbol is a function. """
@@ -250,6 +255,11 @@ def has_symbol(self, name):
         """ Check if this object file has a symbol with name 'name' """
         return name in self.symbol_map
 
+    def is_defined_global(self, name):
+        """ Test if the symbol "name" is defined and global in "self" """
+        sym = self.symbol_map.get(name)
+        return sym and sym.is_defined_global
+
     def get_symbol(self, name):
         """ Get a symbol """
         return self.symbol_map[name]