x/mobile: generated objective-C header protocols doesn't contain code comments

[hilariocoelho]

What version of Go are you using (go version)?

$ go version
go version go1.16 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="on"
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/itsector/Library/Caches/go-build"
GOENV="/Users/itsector/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/itsector/go/pkg/mod"
GOOS="darwin"
GOPATH="/Users/itsector/go"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/spawn2kill/sdk/go1.16"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/spawn2kill/sdk/go1.16/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.16"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/zw/k3cy323s26zcn5tdrvqy0p2r0000gp/T/go-build3668600279=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I have a small library that I want to export to Swift which exports an interface that should be implemented in Swift code. The generated Objective-C header file doesn't contain the code comments on the @protocol declaration but it does on the @interface class declaration that implements the exported interface.

A simple Golang code sample:

package code_test

// ImplementMeInSwift exposed interface.
type ImplementMeInSwift interface {
	// ImplementThisMethod this method should be implemented in Swift code
	ImplementThisMethod(str string)
}

What did you expect to see?

// Objective-C API for talking to code_test Go package.
//   gobind -lang=objc code_test
//
// File is generated by gobind. Do not edit.

#ifndef __Code_test_H__
#define __Code_test_H__

@import Foundation;
#include "ref.h"
#include "Universe.objc.h"


@protocol Code_testImplementMeInSwift;
@class Code_testImplementMeInSwift;

@protocol Code_testImplementMeInSwift <NSObject>
/**
 * ImplementThisMethod this method should be implemented in Swift code
 */
- (void)implementThisMethod:(NSString* _Nullable)str;
@end

@class Code_testImplementMeInSwift;

/**
 * ImplementMeInSwift exposed interface.
 */
@interface Code_testImplementMeInSwift : NSObject <goSeqRefInterface, Code_testImplementMeInSwift> {
}
@property(strong, readonly) _Nonnull id _ref;

- (nonnull instancetype)initWithRef:(_Nonnull id)ref;
/**
 * ImplementThisMethod this method should be implemented in Swift code
 */
- (void)implementThisMethod:(NSString* _Nullable)str;
@end

#endif

What did you see instead?

// Objective-C API for talking to code_test Go package.
//   gobind -lang=objc code_test
//
// File is generated by gobind. Do not edit.

#ifndef __Code_test_H__
#define __Code_test_H__

@import Foundation;
#include "ref.h"
#include "Universe.objc.h"


@protocol Code_testImplementMeInSwift;
@class Code_testImplementMeInSwift;

@protocol Code_testImplementMeInSwift <NSObject>
- (void)implementThisMethod:(NSString* _Nullable)str;
@end

@class Code_testImplementMeInSwift;

/**
 * ImplementMeInSwift exposed interface.
 */
@interface Code_testImplementMeInSwift : NSObject <goSeqRefInterface, Code_testImplementMeInSwift> {
}
@property(strong, readonly) _Nonnull id _ref;

- (nonnull instancetype)initWithRef:(_Nonnull id)ref;
/**
 * ImplementThisMethod this method should be implemented in Swift code
 */
- (void)implementThisMethod:(NSString* _Nullable)str;
@end

#endif

[hilariocoelho]

@dmitshur any updates on this? golang/mobile#67 fixes the issue and is ready to be merged

[gopherbot]

Change https://go.dev/cl/331429 mentions this issue: bind: added protocol documentation to Objective-C generated file