Simplify control-flow

Summary:
This is some weird control-flow from over a decade ago.
It needs to be simplified to be readable and easy to follow.

Reviewed By: nprintz

Differential Revision: D82535143

fbshipit-source-id: 3918e78ea616afde63a199843609a6035bcc84e0

Author: echistyakov

thrift/compiler/generate/templates/go/svc/processor.mustache

@@ -111,8 +111,7 @@ func (p *{{> svc/proc_func_name}}) Read(decoder thrift.Decoder) (thrift.Struct,
     return args, nil
 }
 
-func (p *{{> svc/proc_func_name}}) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) (err error) {
-    var err2 error
+func (p *{{> svc/proc_func_name}}) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) error {
     messageType := thrift.REPLY
     switch {{#function:exceptions?}}v := {{/function:exceptions?}}result.(type) {
     {{#function:exceptions}}
@@ -125,19 +124,16 @@ func (p *{{> svc/proc_func_name}}) Write(seqId int32, result thrift.WritableStru
         messageType = thrift.EXCEPTION
     }
 
-    if err2 = encoder.WriteMessageBegin("{{function:name}}", messageType, seqId); err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageBegin("{{function:name}}", messageType, seqId); err != nil {
+        return err
     }
-    if err2 = result.Write(encoder); err == nil && err2 != nil {
-        err = err2
+    if err := result.Write(encoder); err != nil {
+        return err
     }
-    if err2 = encoder.WriteMessageEnd(); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageEnd(); err != nil {
+        return err
     }
-    if err2 = encoder.Flush(); err == nil && err2 != nil {
-        err = err2
-    }
-    return err
+    return encoder.Flush()
 }
 
 func (p *{{> svc/proc_func_name}}) RunContext(ctx context.Context, reqStruct thrift.ReadableStruct) (thrift.WritableStruct, thrift.ApplicationExceptionIf) {

thrift/compiler/test/fixtures/adapter/out/go/gen-go/svcs.go

@@ -130,27 +130,23 @@ func (p *procFuncServiceFunc) Read(decoder thrift.Decoder) (thrift.Struct, error
     return args, nil
 }
 
-func (p *procFuncServiceFunc) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) (err error) {
-    var err2 error
+func (p *procFuncServiceFunc) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) error {
     messageType := thrift.REPLY
     switch result.(type) {
     case *thrift.ApplicationException:
         messageType = thrift.EXCEPTION
     }
 
-    if err2 = encoder.WriteMessageBegin("func", messageType, seqId); err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageBegin("func", messageType, seqId); err != nil {
+        return err
     }
-    if err2 = result.Write(encoder); err == nil && err2 != nil {
-        err = err2
+    if err := result.Write(encoder); err != nil {
+        return err
     }
-    if err2 = encoder.WriteMessageEnd(); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageEnd(); err != nil {
+        return err
     }
-    if err2 = encoder.Flush(); err == nil && err2 != nil {
-        err = err2
-    }
-    return err
+    return encoder.Flush()
 }
 
 func (p *procFuncServiceFunc) RunContext(ctx context.Context, reqStruct thrift.ReadableStruct) (thrift.WritableStruct, thrift.ApplicationExceptionIf) {
@@ -286,27 +282,23 @@ func (p *procFuncAdapterServiceCount) Read(decoder thrift.Decoder) (thrift.Struc
     return args, nil
 }
 
-func (p *procFuncAdapterServiceCount) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) (err error) {
-    var err2 error
+func (p *procFuncAdapterServiceCount) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) error {
     messageType := thrift.REPLY
     switch result.(type) {
     case *thrift.ApplicationException:
         messageType = thrift.EXCEPTION
     }
 
-    if err2 = encoder.WriteMessageBegin("count", messageType, seqId); err2 != nil {
-        err = err2
-    }
-    if err2 = result.Write(encoder); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageBegin("count", messageType, seqId); err != nil {
+        return err
     }
-    if err2 = encoder.WriteMessageEnd(); err == nil && err2 != nil {
-        err = err2
+    if err := result.Write(encoder); err != nil {
+        return err
     }
-    if err2 = encoder.Flush(); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageEnd(); err != nil {
+        return err
     }
-    return err
+    return encoder.Flush()
 }
 
 func (p *procFuncAdapterServiceCount) RunContext(ctx context.Context, reqStruct thrift.ReadableStruct) (thrift.WritableStruct, thrift.ApplicationExceptionIf) {
@@ -337,27 +329,23 @@ func (p *procFuncAdapterServiceAdaptedTypes) Read(decoder thrift.Decoder) (thrif
     return args, nil
 }
 
-func (p *procFuncAdapterServiceAdaptedTypes) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) (err error) {
-    var err2 error
+func (p *procFuncAdapterServiceAdaptedTypes) Write(seqId int32, result thrift.WritableStruct, encoder thrift.Encoder) error {
     messageType := thrift.REPLY
     switch result.(type) {
     case *thrift.ApplicationException:
         messageType = thrift.EXCEPTION
     }
 
-    if err2 = encoder.WriteMessageBegin("adaptedTypes", messageType, seqId); err2 != nil {
-        err = err2
-    }
-    if err2 = result.Write(encoder); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageBegin("adaptedTypes", messageType, seqId); err != nil {
+        return err
     }
-    if err2 = encoder.WriteMessageEnd(); err == nil && err2 != nil {
-        err = err2
+    if err := result.Write(encoder); err != nil {
+        return err
     }
-    if err2 = encoder.Flush(); err == nil && err2 != nil {
-        err = err2
+    if err := encoder.WriteMessageEnd(); err != nil {
+        return err
     }
-    return err
+    return encoder.Flush()
 }
 
 func (p *procFuncAdapterServiceAdaptedTypes) RunContext(ctx context.Context, reqStruct thrift.ReadableStruct) (thrift.WritableStruct, thrift.ApplicationExceptionIf) {