From 6c96746ab951d7393b247dea6beedb4d342f02bb Mon Sep 17 00:00:00 2001
From: USAMI Kenta <tadsan@zonu.me>
Date: Thu, 28 May 2026 09:58:33 +0900
Subject: [PATCH] Narrow Resolv::DNS resource methods by typeclass

`Resolv::DNS#getresource` / `#getresources` / `#each_resource` /
`#extract_resources` accept a typeclass argument (e.g.
`Resolv::DNS::Resource::IN::MX`) that fully determines the returned
resource subclass. The signatures returned the upper bound
`Resolv::DNS::Resource`, dropping that information; callers using
subclass-specific methods like `MX#exchange` then need a downcast.

A bounded generic (`[T < Resolv::DNS::Resource] (..., singleton(T)) ->
Array[T]`) would be the cleanest shape, but RBS does not currently
accept a type variable inside `singleton(...)` (`Could not find ::T`).

Fall back to per-subclass overloads for the `Resolv::DNS::Resource::IN::*`
leaf types and `Generic`, with the previous wide overload kept as the
trailing fallback (which also covers `Resource::ANY` and other classes
under `Resolv::DNS::Query`).
---
 stdlib/resolv/0/resolv.rbs | 66 +++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 5 deletions(-)

diff --git a/stdlib/resolv/0/resolv.rbs b/stdlib/resolv/0/resolv.rbs
index 4798ef8f2..4ab7ee839 100644
--- a/stdlib/resolv/0/resolv.rbs
+++ b/stdlib/resolv/0/resolv.rbs
@@ -218,9 +218,37 @@ class Resolv::DNS
   # Iterates over all `typeclass` DNS resources for `name`.  See #getresource for
   # argument details.
   #
-  def each_resource: (dns_name name, singleton(Resolv::DNS::Query) typeclass) { (Resolv::DNS::Resource) -> void } -> void
-
-  def extract_resources: (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Query) typeclass) { (Resolv::DNS::Resource) -> void } -> void
+  def each_resource: (dns_name name, singleton(Resolv::DNS::Resource::IN::A) typeclass) { (Resolv::DNS::Resource::IN::A) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::AAAA) typeclass) { (Resolv::DNS::Resource::IN::AAAA) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::CNAME) typeclass) { (Resolv::DNS::Resource::IN::CNAME) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::HINFO) typeclass) { (Resolv::DNS::Resource::IN::HINFO) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::LOC) typeclass) { (Resolv::DNS::Resource::IN::LOC) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::MINFO) typeclass) { (Resolv::DNS::Resource::IN::MINFO) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::MX) typeclass) { (Resolv::DNS::Resource::IN::MX) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::NS) typeclass) { (Resolv::DNS::Resource::IN::NS) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::PTR) typeclass) { (Resolv::DNS::Resource::IN::PTR) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::SOA) typeclass) { (Resolv::DNS::Resource::IN::SOA) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::SRV) typeclass) { (Resolv::DNS::Resource::IN::SRV) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::TXT) typeclass) { (Resolv::DNS::Resource::IN::TXT) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::IN::WKS) typeclass) { (Resolv::DNS::Resource::IN::WKS) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Resource::Generic) typeclass) { (Resolv::DNS::Resource::Generic) -> void } -> void
+                   | (dns_name name, singleton(Resolv::DNS::Query) typeclass) { (Resolv::DNS::Resource) -> void } -> void
+
+  def extract_resources: (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::A) typeclass) { (Resolv::DNS::Resource::IN::A) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::AAAA) typeclass) { (Resolv::DNS::Resource::IN::AAAA) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::CNAME) typeclass) { (Resolv::DNS::Resource::IN::CNAME) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::HINFO) typeclass) { (Resolv::DNS::Resource::IN::HINFO) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::LOC) typeclass) { (Resolv::DNS::Resource::IN::LOC) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::MINFO) typeclass) { (Resolv::DNS::Resource::IN::MINFO) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::MX) typeclass) { (Resolv::DNS::Resource::IN::MX) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::NS) typeclass) { (Resolv::DNS::Resource::IN::NS) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::PTR) typeclass) { (Resolv::DNS::Resource::IN::PTR) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::SOA) typeclass) { (Resolv::DNS::Resource::IN::SOA) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::SRV) typeclass) { (Resolv::DNS::Resource::IN::SRV) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::TXT) typeclass) { (Resolv::DNS::Resource::IN::TXT) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::IN::WKS) typeclass) { (Resolv::DNS::Resource::IN::WKS) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Resource::Generic) typeclass) { (Resolv::DNS::Resource::Generic) -> void } -> void
+                       | (Resolv::DNS::Message msg, dns_name name, singleton(Resolv::DNS::Query) typeclass) { (Resolv::DNS::Resource) -> void } -> void
 
   # <!--
   #   rdoc-file=lib/resolv.rb
@@ -299,7 +327,21 @@ class Resolv::DNS
   # Returned resource is represented as a Resolv::DNS::Resource instance, i.e.
   # Resolv::DNS::Resource::IN::A.
   #
-  def getresource: (dns_name name, singleton(Resolv::DNS::Query) typeclass) -> Resolv::DNS::Resource
+  def getresource: (dns_name name, singleton(Resolv::DNS::Resource::IN::A) typeclass) -> Resolv::DNS::Resource::IN::A
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::AAAA) typeclass) -> Resolv::DNS::Resource::IN::AAAA
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::CNAME) typeclass) -> Resolv::DNS::Resource::IN::CNAME
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::HINFO) typeclass) -> Resolv::DNS::Resource::IN::HINFO
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::LOC) typeclass) -> Resolv::DNS::Resource::IN::LOC
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::MINFO) typeclass) -> Resolv::DNS::Resource::IN::MINFO
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::MX) typeclass) -> Resolv::DNS::Resource::IN::MX
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::NS) typeclass) -> Resolv::DNS::Resource::IN::NS
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::PTR) typeclass) -> Resolv::DNS::Resource::IN::PTR
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::SOA) typeclass) -> Resolv::DNS::Resource::IN::SOA
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::SRV) typeclass) -> Resolv::DNS::Resource::IN::SRV
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::TXT) typeclass) -> Resolv::DNS::Resource::IN::TXT
+                 | (dns_name name, singleton(Resolv::DNS::Resource::IN::WKS) typeclass) -> Resolv::DNS::Resource::IN::WKS
+                 | (dns_name name, singleton(Resolv::DNS::Resource::Generic) typeclass) -> Resolv::DNS::Resource::Generic
+                 | (dns_name name, singleton(Resolv::DNS::Query) typeclass) -> Resolv::DNS::Resource
 
   # <!--
   #   rdoc-file=lib/resolv.rb
@@ -308,7 +350,21 @@ class Resolv::DNS
   # Looks up all `typeclass` DNS resources for `name`.  See #getresource for
   # argument details.
   #
-  def getresources: (dns_name name, singleton(Resolv::DNS::Query) typeclass) -> Array[Resolv::DNS::Resource]
+  def getresources: (dns_name name, singleton(Resolv::DNS::Resource::IN::A) typeclass) -> Array[Resolv::DNS::Resource::IN::A]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::AAAA) typeclass) -> Array[Resolv::DNS::Resource::IN::AAAA]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::CNAME) typeclass) -> Array[Resolv::DNS::Resource::IN::CNAME]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::HINFO) typeclass) -> Array[Resolv::DNS::Resource::IN::HINFO]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::LOC) typeclass) -> Array[Resolv::DNS::Resource::IN::LOC]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::MINFO) typeclass) -> Array[Resolv::DNS::Resource::IN::MINFO]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::MX) typeclass) -> Array[Resolv::DNS::Resource::IN::MX]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::NS) typeclass) -> Array[Resolv::DNS::Resource::IN::NS]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::PTR) typeclass) -> Array[Resolv::DNS::Resource::IN::PTR]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::SOA) typeclass) -> Array[Resolv::DNS::Resource::IN::SOA]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::SRV) typeclass) -> Array[Resolv::DNS::Resource::IN::SRV]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::TXT) typeclass) -> Array[Resolv::DNS::Resource::IN::TXT]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::IN::WKS) typeclass) -> Array[Resolv::DNS::Resource::IN::WKS]
+                  | (dns_name name, singleton(Resolv::DNS::Resource::Generic) typeclass) -> Array[Resolv::DNS::Resource::Generic]
+                  | (dns_name name, singleton(Resolv::DNS::Query) typeclass) -> Array[Resolv::DNS::Resource]
 
   def lazy_initialize: () -> untyped