DescribeStreamOutcome 报告为“不完整类型”

Question

我从 github 克隆了 aws-sdk-cpp，并且成功地构建了它（测试也通过了）。我没有做“make install”。我想专门编译 SDK 的 dynamodbstreams 部分，所以我在 cmake 参数中添加了 -DBUILD_ONLY="dynamodbstreams" 。我写了一个小测试代码，但由于报告未定义的 DescribeStreamOutcome 类型（“inclomplete 类型”）而无法编译。但是，它存在于它应该存在的头文件中。

cmake 版本：3.5.1，g++ 版本：5.4.0（我暂时没试过clang）

任何人都可以查看代码并指出问题所在吗？

我有以下代码：

#include "aws/core/Aws.h"
#include "aws/dynamodbstreams/DynamoDBStreamsClient.h"
#include "aws/dynamodbstreams/model/DescribeStreamRequest.h"

int main()
{
    Aws::SDKOptions options;
    Aws::InitAPI(options);

    Aws::DynamoDBStreams::DynamoDBStreamsClient client;
    Aws::DynamoDBStreams::Model::DescribeStreamRequest request;
    auto result = client.DescribeStream(request);
    if (result.IsSuccess()) {}

    Aws::ShutdownAPI(options);

    return 0;
}

有了这个 Makefile：

all: test

CFLAGS = -std=c++11 -Wall -fPIC \
-I$(SDK_SOURCE_DIR)/aws-cpp-sdk-core/include \
-I$(SDK_SOURCE_DIR)/aws-cpp-sdk-dynamodbstreams/include

LFLAGS = -shared -fPIC \
-L$(SDK_BUILD_DIR)/aws-cpp-sdk-core -laws-cpp-sdk-core \
-L$(SDK_BUILD_DIR)/aws-cpp-sdk-dynamodbstreams -laws-cpp-sdk-dynamodbstreams

test: test.o \
     $(CXX) -shared -fPIC -o $@ $^

test.o: test.cc
     $(CXX) $(CFLAGS) -c -o $@ $<

.PHONY: clean
clean:
     rm -f *.o test

制作时出现以下错误：

g++ -std=c++11 -Wall -fPIC -I/home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-core/include -I/home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-dynamodbstreams/include -c -o test.o test.cc
test.cc: In function ‘int main()’:
test.cc:12:48: error: invalid use of incomplete type ‘Aws::DynamoDBStreams::Model::DescribeStreamOutcome {aka class Aws::Utils::Outcome<Aws::DynamoDBStreams::Model::DescribeStreamResult, Aws::Client::AWSError<Aws::DynamoDBStreams::DynamoDBStreamsErrors> >}’
     auto result = client.DescribeStream(request);
                                                ^
In file included from /home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-core/include/aws/core/utils/crypto/Hash.h:19:0,
                 from /home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-core/include/aws/core/client/AWSClient.h:23,
                 from /home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-dynamodbstreams/include/aws/dynamodbstreams/DynamoDBStreamsClient.h:21,
                 from test.cc:2:
/home/attilacsabai/git-projects/aws-sdk-cpp/aws-cpp-sdk-core/include/aws/core/utils/crypto/HashResult.h:26:50: note: declaration of ‘Aws::DynamoDBStreams::Model::DescribeStreamOutcome {aka class Aws::Utils::Outcome<Aws::DynamoDBStreams::Model::DescribeStreamResult, Aws::Client::AWSError<Aws::DynamoDBStreams::DynamoDBStreamsErrors> >}’
         template< typename R, typename E > class Outcome;
                                                  ^
Makefile:16: recipe for target 'test.o' failed
make: *** [test.o] Error 1

但是，DescribeStreamOutcome 是在 DynamoDBStreamsClient.h 中定义的：

$ grep -i describestreamoutcome $SDK_SOURCE_DIR/aws-cpp-sdk-dynamodbstreams/include/aws/dynamodbstreams/DynamoDBStreamsClient.h | head -1
typedef Aws::Utils::Outcome<DescribeStreamResult, Aws::Client::AWSError<DynamoDBStreamsErrors>> DescribeStreamOutcome;

那你能帮帮我吗？谢谢。

Answer 1

“DescribeStreamOutcome 在 DynamoDBStreamsClient.h 中定义”语句不正确。 DynamoDBStreamsClient.h 中的那一行定义了 Outcome 实例化的别名。

clang 给出了更简洁的错误信息：

meow.cpp:12:26: error: implicit instantiation of undefined template 'Aws::Utils::Outcome<Aws::DynamoDBStreams::Model::DescribeStreamResult,
      Aws::Client::AWSError<Aws::DynamoDBStreams::DynamoDBStreamsErrors> >'
    auto result = client.DescribeStream(request);
                         ^
/usr/local/include/aws/dynamodbstreams/DynamoDBStreamsClient.h:44:43: note: template is declared here
  template< typename R, typename E> class Outcome;
                                          ^

你需要#include "aws/core/utils/Outcome.h"

也许aws/dynamodbstreams/DynamoDBStreamsClient.h 应该包含Outcome.h，尽管使用 DynamoDBStreamsClient 的代码在没有它的情况下编译，只要您不调用任何返回结果的方法。