+ add an explicit function to compare two return types of a function or operator (in contrast to compare_defs it also treats two undefined defs as different if they aren't the exactly same)

compiler/defcmp.pas

@@ -149,6 +149,11 @@ interface
     }
     function compare_paras(para1,para2 : TFPObjectList; acp : tcompare_paras_type; cpoptions: tcompare_paras_options):tequaltype;
 
+    { Compares the compatibility of two return types (in contrast to
+      compare_defs the cdo_strict_undefined_check will be passed to
+      compare_defs_ext as well) }
+    function compare_rettype(def1,def2:tdef):tequaltype;
+
     { True if a function can be assigned to a procvar }
     { changed first argument type to pabstractprocdef so that it can also be }
     { used to test compatibility between two pprocvardefs (JM)               }
@@ -2543,6 +2548,15 @@ implementation
       end;
 
 
+    function compare_rettype(def1,def2:tdef):tequaltype;
+      var
+        doconv : tconverttype;
+        pd : tprocdef;
+      begin
+        result:=compare_defs_ext(def1,def2,nothingn,doconv,pd,[cdo_check_operator,cdo_allow_variant,cdo_strict_undefined_check]);
+      end;
+
+
     function proc_to_procvar_equal_internal(def1:tabstractprocdef;def2:tabstractprocdef;checkincompatibleuniv,ignoreself: boolean):tequaltype;
       var
         eq: tequaltype;