plugin: Drop library version matching

This change drops the check made by the ThriftRW Plugin system verifying
that the version of ThriftRW talking to the plugin is the same as the
version of ThriftRW used to compile the plugin.

This check is unnecessay because we already verify the API version,
which is defined in the Thrift file.

This check is more trouble than it's worth as it's constantly tripping
up users and we don't change the plugin API nearly often enough to need
this.

CHANGELOG.md

@@ -5,7 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
-- No changes yet.
+### Fixed
+- plugin: Library version matching was dropped.
 
 ## [1.15.0] - 2019-01-14
 ### Changed

internal/plugin/errors.go

@@ -21,7 +21,6 @@
 package plugin
 
 import (
-	"errors"
 	"fmt"
 
 	"go.uber.org/thriftrw/internal/semver"
@@ -52,8 +51,6 @@ func (e errAPIVersionMismatch) Error() string {
 	return fmt.Sprintf("plugin API version mismatch: expected %v but got %v", e.Want, e.Got)
 }
 
-var errVersionIsRequired = errors.New("Version is required")
-
 type errVersionMismatch struct {
 	Want semver.Range
 	Got  string

internal/plugin/transport.go

@@ -27,28 +27,14 @@ import (
 
 	"go.uber.org/thriftrw/internal/envelope"
 	"go.uber.org/thriftrw/internal/multiplex"
-	"go.uber.org/thriftrw/internal/semver"
 	"go.uber.org/thriftrw/plugin/api"
 	"go.uber.org/thriftrw/protocol"
-	"go.uber.org/thriftrw/version"
 
 	"go.uber.org/atomic"
 	"go.uber.org/multierr"
 )
 
-var (
-	_proto      = protocol.Binary
-	compatRange = computeCompatibleRange()
-)
-
-func computeCompatibleRange() semver.Range {
-	v, err := semver.Parse(version.Version)
-	if err != nil {
-		panic(err)
-	}
-
-	return semver.CompatibleRange(v)
-}
+var _proto = protocol.Binary
 
 // transportHandle is a Handle to a plugin which is behind an envelope.Transport.
 type transportHandle struct {
@@ -88,30 +74,6 @@ func NewTransportHandle(name string, t envelope.Transport) (Handle, error) {
 		}
 	}
 
-	// If we got here, the API version matches so the plugin must have
-	// provided the Version
-	if handshake.LibraryVersion == nil {
-		return nil, errHandshakeFailed{
-			Name:   name,
-			Reason: errVersionIsRequired,
-		}
-	}
-
-	version, err := semver.Parse(*handshake.LibraryVersion)
-	if err != nil {
-		return nil, errHandshakeFailed{Name: name, Reason: err}
-	}
-
-	if !compatRange.Contains(version) {
-		return nil, errHandshakeFailed{
-			Name: name,
-			Reason: errVersionMismatch{
-				Want: compatRange,
-				Got:  *handshake.LibraryVersion,
-			},
-		}
-	}
-
 	features := make(map[api.Feature]struct{}, len(handshake.Features))
 	for _, feature := range handshake.Features {
 		features[feature] = struct{}{}

internal/plugin/transport_test.go

@@ -144,42 +144,6 @@ func TestTransportHandleHandshakeError(t *testing.T) {
 			wantError: `handshake with plugin "foo" failed: ` +
 				fmt.Sprintf("plugin API version mismatch: expected %d but got 42", api.APIVersion),
 		},
-		{
-			desc: "missing version",
-			name: "foo",
-			response: &api.HandshakeResponse{
-				Name:           "foo",
-				APIVersion:     api.APIVersion,
-				LibraryVersion: nil,
-				Features:       []api.Feature{},
-			},
-			wantError: `handshake with plugin "foo" failed: Version is required`,
-		},
-		{
-			desc: "unparseable version",
-			name: "foo",
-			response: &api.HandshakeResponse{
-				Name:           "foo",
-				APIVersion:     api.APIVersion,
-				LibraryVersion: ptr.String("hello"),
-				Features:       []api.Feature{},
-			},
-			wantError: `handshake with plugin "foo" failed: ` +
-				`cannot parse as semantic version: "hello"`,
-		},
-		{
-			desc: "semver mismatch",
-			name: "foo",
-			response: &api.HandshakeResponse{
-				Name:           "foo",
-				APIVersion:     api.APIVersion,
-				LibraryVersion: ptr.String("12.3.4"),
-				Features:       []api.Feature{},
-			},
-			wantError: `handshake with plugin "foo" failed: ` +
-				"plugin compiled with the wrong version of ThriftRW: " +
-				fmt.Sprintf("expected >=%v and <%v but got 12.3.4", &compatRange.Begin, &compatRange.End),
-		},
 	}
 
 	for _, tt := range tests {