Correctly handle tentative struct/union and array definitions that are not completed.

In the case of structs or unions, an error is now produced. This addresses one of the problems mentioned in issue #53.

In the case of arrays, tentative definitions like "int i[];" are now permitted at file scope. If not completed by a subsequent definition, this winds up producing an array with one element, initialized to 0. See the discussion and example in C99/C11 section 6.9.2 (or C90 section 6.7.2 and example in TC1).

Parser.pas

@@ -3592,7 +3592,8 @@ else {if not isFunction then} begin
             end; {if}
                                         {check to insure array sizes are specified}
          if storageClass <> typedefsy then
-            CheckArray(variable, (storageClass = externsy) or doingParameters);
+            CheckArray(variable,
+               (storageClass = externsy) or doingParameters or not doingFunction);
                                         {allocate space}
          if variable^.storage = stackFrame then begin
             variable^.lln := GetLocalLabel;

Symbol.pas

@@ -448,6 +448,7 @@ procedure DoGlobals;
       size: longint;                    {size of the array}
       sp: identPtr;                     {pointer to a symbol table entry}
       tPtr: typePtr;                    {type of global array/struct/union}
+      msg: stringPtr;                   {error message ptr}
 
    begin {GenArrays}
    didOne := false;
@@ -502,6 +503,26 @@ procedure DoGlobals;
                   end {if}
                else begin
                   size := sp^.itype^.size;
+                  if size = 0 then begin
+                     if sp^.itype^.kind = arrayType then begin
+                                        {implicitly initialize with one element}
+                        size := sp^.itype^.aType^.size;
+                        end {if}
+                     else begin
+                        numErrors := numErrors+1;
+                        new(msg);
+                        msg^ := concat('The struct or union ''', sp^.name^,
+                           ''' has incomplete type that was never completed.');
+                        writeln('*** ', msg^);
+                        if terminalErrors then begin
+                           if enterEditor then
+                              ExitToEditor(msg, ord4(firstPtr)-ord4(bofPtr))
+                           else
+                              TermError(0);
+                           end; {if}
+                        liDCBGS.merrf := 16;
+                        end; {else}
+                     end; {if}
                   Gen2Name(dc_glb, long(size).lsw & $7FFF,
                      ord(sp^.storage = private), sp^.name);
         	  size := size & $FFFF8000;
@@ -567,6 +588,9 @@ procedure DoGlobals;
                      otherwise: Error(57);
                      end; {case}
                   end {if}
+               {else if sp^.itype^.size = 0 then begin
+                  Error(57);
+                  end {else if}
                else
                   Gen2Name(dc_glb, ord(sp^.itype^.size),
                      ord(sp^.storage = private), sp^.name);