fix Issue 5841 - alias grammar is incorrect

declaration.dd

@@ -3,11 +3,27 @@ Ddoc
 $(SPEC_S Declarations,
 
 $(GRAMMAR
-$(GNAME Declaration):
-$(V1    $(B typedef) $(I Decl)
-)    $(B alias) $(I Decl)
-    $(I Decl)
-
+$(V1 $(GNAME Declaration):
+    $(GLINK TypedefDeclaration)
+    $(GLINK AliasDeclaration)
+    $(GLINK Decl)
+
+$(GNAME TypedefDeclaration):
+    $(B typedef) $(GLINK Decl)
+
+$(GNAME AliasDeclaration):
+    $(B alias) $(GLINK Decl)
+)$(V2 $(GNAME Declaration):
+    $(GLINK AliasDeclaration)
+    $(GLINK AliasThisDeclaration)
+    $(GLINK Decl)
+
+$(GNAME AliasDeclaration):
+    $(B alias) $(GLINK BasicType) $(GLINK Declarator)
+
+$(GNAME AliasThisDeclaration):
+    $(B alias) $(I Identifier) $(B this)
+)
 $(GNAME Decl):
     $(GLINK StorageClasses) $(I Decl)
     $(GLINK BasicType) $(GLINK Declarators) $(B ;)
@@ -368,9 +384,8 @@ myint m;        // initialized to 7
 <h3><a name="alias">Type Aliasing</a></h3>
 
         $(P
-        It's sometimes convenient to use an alias for a type, such as a shorthand for typing
-        out a long, complex type like a pointer to a function. In D, this is done with the
-        alias declaration:
+	$(GLINK AliasDeclaration)s create a symbol that is an alias for another type,
+	and can be used anywhere that other type may appear.
         )
 
 --------------------