From 2e7efad7b9659ec3864d6808ddba7371c10f2173 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Tue, 14 Dec 2021 17:24:33 +0100
Subject: [PATCH 1/2] remove proof spec from ClientState interface

---
 modules/core/exported/client.go                            | 2 --
 modules/light-clients/06-solomachine/types/client_state.go | 7 -------
 modules/light-clients/09-localhost/types/client_state.go   | 7 -------
 3 files changed, 16 deletions(-)

diff --git a/modules/core/exported/client.go b/modules/core/exported/client.go
index de4cbe48c8a..4dce203bea4 100644
--- a/modules/core/exported/client.go
+++ b/modules/core/exported/client.go
@@ -1,7 +1,6 @@
 package exported
 
 import (
-	ics23 "github.com/confio/ics23/go"
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	proto "github.com/gogo/protobuf/proto"
@@ -44,7 +43,6 @@ type ClientState interface {
 	ClientType() string
 	GetLatestHeight() Height
 	Validate() error
-	GetProofSpecs() []*ics23.ProofSpec
 
 	// Initialization function
 	// Clients must validate the initial consensus state, and may store any client-specific metadata
diff --git a/modules/light-clients/06-solomachine/types/client_state.go b/modules/light-clients/06-solomachine/types/client_state.go
index 2ce6eee512e..c99d4f08f64 100644
--- a/modules/light-clients/06-solomachine/types/client_state.go
+++ b/modules/light-clients/06-solomachine/types/client_state.go
@@ -3,8 +3,6 @@ package types
 import (
 	"reflect"
 
-	ics23 "github.com/confio/ics23/go"
-
 	"github.com/cosmos/cosmos-sdk/codec"
 	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -52,11 +50,6 @@ func (cs ClientState) Status(_ sdk.Context, _ sdk.KVStore, _ codec.BinaryCodec)
 	return exported.Active
 }
 
-// GetProofSpecs returns nil proof specs since client state verification uses signatures.
-func (cs ClientState) GetProofSpecs() []*ics23.ProofSpec {
-	return nil
-}
-
 // Validate performs basic validation of the client state fields.
 func (cs ClientState) Validate() error {
 	if cs.Sequence == 0 {
diff --git a/modules/light-clients/09-localhost/types/client_state.go b/modules/light-clients/09-localhost/types/client_state.go
index ab0f7207fdf..b817f7764eb 100644
--- a/modules/light-clients/09-localhost/types/client_state.go
+++ b/modules/light-clients/09-localhost/types/client_state.go
@@ -6,8 +6,6 @@ import (
 	"reflect"
 	"strings"
 
-	ics23 "github.com/confio/ics23/go"
-
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
@@ -60,11 +58,6 @@ func (cs ClientState) Validate() error {
 	return nil
 }
 
-// GetProofSpecs returns nil since localhost does not have to verify proofs
-func (cs ClientState) GetProofSpecs() []*ics23.ProofSpec {
-	return nil
-}
-
 // ZeroCustomFields returns the same client state since there are no custom fields in localhost
 func (cs ClientState) ZeroCustomFields() exported.ClientState {
 	return &cs

From e02e96aa54e71e3a5d85cc03f07bffdc84b8324d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Colin=20Axn=C3=A9r?=
 <25233464+colin-axner@users.noreply.github.com>
Date: Tue, 14 Dec 2021 17:34:55 +0100
Subject: [PATCH 2/2] add changelog and migration doc note

---
 CHANGELOG.md                | 1 +
 docs/migrations/v2-to-v3.md | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f83dc781f2..eb9f13fd013 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -42,6 +42,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking
  
+* (core) [\#629](https://github.com/cosmos/ibc-go/pull/629) Removes the GetProofSpecs from the ClientState interface. This function was previously unused by core IBC.
 * (transfer) [\#517](https://github.com/cosmos/ibc-go/pull/517) Separates the ICS 26 callback functions from `AppModule` into a new type `IBCModule` for ICS 20 transfer.
 * (modules/core/02-client) [\#536](https://github.com/cosmos/ibc-go/pull/536) GetSelfConsensusState return type changed from bool to error.
 
diff --git a/docs/migrations/v2-to-v3.md b/docs/migrations/v2-to-v3.md
index f3fad769d08..d1350bd1163 100644
--- a/docs/migrations/v2-to-v3.md
+++ b/docs/migrations/v2-to-v3.md
@@ -38,4 +38,5 @@ Please review the [mock](../../testing/mock/ibc_module.go) and [transfer](../../
 
 ## IBC Light Clients
 
-- No relevant changes were made in this release.
+The `GetProofSpecs` function has been removed from the `ClientState` interface. This function was previously unused by core IBC. Light clients which don't use this function may remove it. 
+