* dsymutil under darwin "smart links" dwarf info -> make sure we

    use the DW_TAG_typedef entries, because without them a type is
    only locally visible in the file where it is declared (see
    comments)

git-svn-id: trunk@9426 -

compiler/dbgdwarf.pas

@@ -1533,6 +1533,52 @@ implementation
         else
           current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));
 
+        if (target_info.system in systems_darwin) then
+          begin
+            { On Darwin, dwarf info is not linked in the final binary,
+              but kept in the individual object files. This allows for
+              faster linking, but means that you have to keep the object
+              files for debugging and also that gdb only loads in the
+              debug info of a particular object file once you step into
+              or over a procedure in it.
+              
+              To solve this, there is a tool called dsymutil which can
+              extract all the dwarf info from a program's object files.
+              This utility however performs "smart linking" on the dwarf
+              info and throws away all unreferenced dwarf entries. Since
+              variables' types always point to the dwarfino for a tdef
+              and never to that for a typesym, this means all debug
+              entries generated for typesyms are thrown away.
+              
+              The problem with that is that we translate typesyms into
+              DW_TAG_typedef, and gdb's dwarf-2 reader only makes types
+              globally visibly if they are defined using a DW_TAG_typedef.
+              So as a result, before running dsymutil types only become
+              available once you stepped into/over a function in the object
+              file where they are declared, and after running dsymutil they
+              are all gone (printng variables still works because the
+              tdef dwarf info is still available, but you cannot typecast
+              anything outside the declaring units because the type names
+              are not known there).
+              
+              The solution: if a tdef has an associated typesym, let the
+              debug label for the tdef point to a DW_TAG_typedef instead
+              of directly to the tdef itself. And don't write anything
+              special for the typesym itself.
+            }
+          if assigned(def.typesym) and
+             not(df_generic in def.defoptions) then
+            begin
+              current_asmdata.getaddrlabel(TAsmLabel(pointer(labsym)));
+              append_entry(DW_TAG_typedef,false,[
+                DW_AT_name,DW_FORM_string,symname(def.typesym)+#0
+              ]);
+              append_labelentry_ref(DW_AT_type,labsym);
+              finish_entry;
+              current_asmdata.asmlists[al_dwarf_info].concat(tai_symbol.create(labsym,0));
+            end;
+          end;
+
         case def.typ of
           stringdef :
             appenddef_string(tstringdef(def));
@@ -2007,14 +2053,20 @@ implementation
 
       procedure TDebugInfoDwarf.appendsym_type(sym: ttypesym);
         begin
-          if not(df_generic in sym.typedef.defoptions) then
+          if not (target_info.system in systems_darwin) then
             begin
-              append_entry(DW_TAG_typedef,false,[
-                DW_AT_name,DW_FORM_string,symname(sym)+#0
-              ]);
-              append_labelentry_ref(DW_AT_type,def_dwarf_lab(sym.typedef));
-            end;
-          finish_entry;
+              if not(df_generic in sym.typedef.defoptions) then
+                begin
+                  append_entry(DW_TAG_typedef,false,[
+                    DW_AT_name,DW_FORM_string,symname(sym)+#0
+                  ]);
+                  append_labelentry_ref(DW_AT_type,def_dwarf_lab(sym.typedef));
+                end;
+              finish_entry;
+            end
+          else
+            { just queue the def if needed }
+            def_dwarf_lab(sym.typedef);
 
           (* Moved fom append sym, do we need this (MWE)
           { For object types write also the symtable entries }