Fix: wrong ErrorType parsing when a type is referenced before it's defined

spec/parser_spec.cr

@@ -162,6 +162,30 @@ describe Parser do
     fields.size.should eq(2)
   end
 
+  it "parses typedef and recursive struct" do
+    nodes = parse("typedef struct first { struct second *s; } FIRST; struct second { FIRST *f };")
+
+    struct_first = nodes[-3].as(StructOrUnion)
+    struct_first.kind.should eq(:struct)
+    struct_first.name.should eq("struct first")
+    struct_first.fields.size.should eq(1)
+    struct_first.fields.first.name.should eq("s")
+    struct_first.fields.first.type.as(PointerType).type.as(NodeRef).node.as(StructOrUnion).name.should eq("struct second")
+
+    type_first = nodes[-2].as(Typedef)
+    type_first.name.should eq("FIRST")
+    underlying_struct = type_first.type.as(NodeRef).node.as(StructOrUnion)
+    underlying_struct.kind.should eq(:struct)
+    underlying_struct.name.should eq("struct first")
+
+    struct_second = nodes[-1].as(StructOrUnion)
+    struct_second.kind.should eq(:struct)
+    struct_second.name.should eq("struct second")
+    struct_second.fields.size.should eq(1)
+    struct_second.fields.first.name.should eq("f")
+    struct_second.fields.first.type.as(PointerType).type.as(TypedefType).name.should eq("FIRST")
+  end
+
   it "parses typedef enum" do
     nodes = parse("typedef enum { x, y } point;")
     type = nodes.last.as(Typedef)

src/crystal_lib/parser.cr

@@ -143,7 +143,15 @@ class CrystalLib::Parser
   def visit_typedef_declaration(cursor)
     name = cursor.spelling
     type = type(cursor.typedef_decl_underlying_type)
-    named_types[name] = TypedefType.new(name, type)
+
+    if named_types.has_key?(name)
+      # this type definition might have been referenced -and created- before,
+      # in this case we just make sure it refers to the right underlying type
+      named_types[name].as(TypedefType).type = type
+    else
+      named_types[name] = TypedefType.new(name, type)
+    end
+
     Typedef.new(name, type)
   end
 
@@ -248,10 +256,15 @@ class CrystalLib::Parser
     when Clang::TypeKind::Typedef
       spelling = type.spelling
       spelling = spelling.gsub("const ", "").gsub("volatile ", "")
-      if !named_types.has_key?(spelling) && spelling == "__builtin_va_list"
+
+      if named_types.has_key?(spelling)
+        named_types[spelling]
+      elsif spelling == "__builtin_va_list"
         VaListType.new
       else
-        named_types[spelling]? || error_type(spelling)
+        # create a new named type in case the type is referenced here but not yet declared
+        # (underlying type is set to ErrorType and will be overwritten by the declaration)
+        named_types[spelling] = TypedefType.new(spelling, error_type(spelling))
       end
     when Clang::TypeKind::Unexposed,
          Clang::TypeKind::Elaborated