go语言protoc编译问题-protoc-gen-go: unable to determine Go import path for “searchnode.proto”

最近换了个电脑，重新配置go语言的开发环境，可是使用protoc编译proto协议文件的时候出现了问题，找了挺久不知道什么原因。最后找到了一个解决办法，具体原因暂时还是不明白，如果有朋友知道的话，也请不吝赐教，感谢。
可在protoc中指定以下参数避免报错。

option go_package = “./SearchNode”;

test.proto

syntax = "proto3";
package VectorSearch.SearchNode;   // 指定proto的包名
//  option go_package = "./SearchNode";   // 编译为.go文件最好指定的参数

message Item {
    string id = 1;
    float  score = 2;
    repeated Field fields = 3;
}

message Field {
    string key = 1;              // 字段名
    string value = 2;            // 值
}

message SearchNodeReq {
    string request_id = 1;       // 请求id
    string index_name = 2;       // 搜索对应索引名称
    int32  cluster_num = 3;      // 查询簇数量,
    int32  request_num = 4;      // 请求数量
    repeated float vector = 5;   // 搜索向量值
}

message SearchNodeResp {
    int32    ret_code = 1;       // 返回码
    string   err_msg = 2;        // 错误信息
    repeated Item results = 3;   // 搜索结果列表
}

service SearchNode {
    rpc Search(SearchNodeReq) returns (SearchNodeResp) {}
}

刚开始在文件中没有加上option go_package = “./SearchNode”; -->报错，提示你能导入test.proto文件

运行以下命令都报错
只编译编码部分
protoc -I=. --go_out=. test.proto
编译编码部分和服务代码
protoc -I=. --go_out=plugins=grpc:. test.proto

// 报错信息
$ protoc -I . --go_out=plugins=grpc:.  test.proto
protoc-gen-go: unable to determine Go import path for "test.proto"

Please specify either:
        • a "go_package" option in the .proto source file, or
        • a "M" argument on the command line.

See https://developers.google.com/protocol-buffers/docs/reference/go-generated#package for more information.

--go_out: protoc-gen-go: Plugin failed with status code 1.

后来在文件头部加入

option go_package = "path/package_name";   path指定.go文件放置的路径，package_name表示包名   
ps:
  option go_package = "./SearchNode";     //  path = ./  ,  package_name=SearchNode

运行以下命令，就可以编译成功了，
protoc -I=PATH指定要在其中搜索
                              导入的目录 。可以多次指定；
                              目录将按顺序搜索。如果未
                              给出，则使用当前工作目录。
                      指定要使用的插件可执行文件。

protoc -I=. --go_out=plugins=grpc:. searchnode/searchnode.proto
命令解释
-I表示输入位置
--go_out后接的地址表示编译好的.go文件放置地址，plugins=grpc表示会将proto文件中指定的服务编译为接口代码

protoc 命令参数解释

Parse PROTO_FILES and generate output based on the options given:
  -IPATH, --proto_path=PATH   Specify the directory in which to search for
                              imports.  May be specified multiple times;
                              directories will be searched in order.  If not
                              given, the current working directory is used.
                              If not found in any of the these directories,
                              the --descriptor_set_in descriptors will be
                              checked for required proto file.
                              
  --version                   Show version info and exit.
  -h, --help                  Show this text and exit.
  
  --encode=MESSAGE_TYPE       Read a text-format message of the given type
                              from standard input and write it in binary
                              to standard output.  The message type must
                              be defined in PROTO_FILES or their imports.
                              
  --decode=MESSAGE_TYPE       Read a binary message of the given type from
                              standard input and write it in text format
                              to standard output.  The message type must
                              be defined in PROTO_FILES or their imports.
                              
  --decode_raw                Read an arbitrary protocol message from
                              standard input and write the raw tag/value
                              pairs in text format to standard output.  No
                              PROTO_FILES should be given when using this
                              flag.
                              
  --descriptor_set_in=FILES   Specifies a delimited list of FILES
                              each containing a FileDescriptorSet (a
                              protocol buffer defined in descriptor.proto).
                              The FileDescriptor for each of the PROTO_FILES
                              provided will be loaded from these
                              FileDescriptorSets. If a FileDescriptor
                              appears multiple times, the first occurrence
                              will be used.
                              
  -oFILE,                     Writes a FileDescriptorSet (a protocol buffer, --descriptor_set_out=FILE defined in descriptor.proto) containing all of
                              the input files to FILE.
                              
  --include_imports           When using --descriptor_set_out, also include
                              all dependencies of the input files in the
                              set, so that the set is self-contained.
                              
  --include_source_info       When using --descriptor_set_out, do not strip
                              SourceCodeInfo from the FileDescriptorProto.
                              This results in vastly larger descriptors that
                              include information about the original
                              location of each decl in the source file as
                              well as surrounding comments.
                              
  --dependency_out=FILE       Write a dependency output file in the format
                              expected by make. This writes the transitive
                              set of input file paths to FILE
                              
  --error_format=FORMAT       Set the format in which to print errors.
                              FORMAT may be 'gcc' (the default) or 'msvs'
                              (Microsoft Visual Studio format).
                              
  --print_free_field_numbers  Print the free field numbers of the messages
                              defined in the given proto files. Groups share
                              the same field number space with the parent
                              message. Extension ranges are counted as
                              occupied fields numbers.

  --plugin=EXECUTABLE         Specifies a plugin executable to use.
                              Normally, protoc searches the PATH for
                              plugins, but you may specify additional
                              executables not in the path using this flag.
                              Additionally, EXECUTABLE may be of the form
                              NAME=PATH, in which case the given plugin name
                              is mapped to the given executable even if
                              the executable's own name differs.
                              
  --cpp_out=OUT_DIR           Generate C++ header and source.
  --csharp_out=OUT_DIR        Generate C# source file.
  --java_out=OUT_DIR          Generate Java source file.
  --js_out=OUT_DIR            Generate JavaScript source.
  --objc_out=OUT_DIR          Generate Objective C header and source.
  --php_out=OUT_DIR           Generate PHP source file.
  --python_out=OUT_DIR        Generate Python source file.
  --ruby_out=OUT_DIR          Generate Ruby source file.
  
  @<filename>                 Read options and filenames from file. If a
                              relative file path is specified, the file
                              will be searched in the working directory.
                              The --proto_path option will not affect how
                              this argument file is searched. Content of
                              the file will be expanded in the position of
                              @<filename> as in the argument list. Note
                              that shell expansion is not applied to the
                              content of the file (i.e., you cannot use
                              quotes, wildcards, escapes, commands, etc.).
                              Each line corresponds to a single argument,
                              even if it contains spaces.