DescribeStreamOutcome报告为“类型不完整”

Question

我从github克隆了aws-sdk-cpp，并设法顺利地构建了它(测试也通过了)。我没有做"make install“。我想以独占方式编译SDK的dynamodbstreams部分，所以我在cmake参数中添加了-DBUILD_ONLY="dynamodbstreams“。我写了一个小的测试代码，但它无法编译，因为报告的DescribeStreamOutcome类型是未定义的(“包含完整类型”)。但是，它存在于头文件中应该存在的位置。

cmake版本: 3.5.1，g++版本: 5.4.0 (我目前还没有尝试过clang )

谁能看一下代码并指出哪里出了问题吗？

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;
}

使用这个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

在执行时，我得到以下错误：

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在DynamoDBStreamsClient.h中定义：

$ 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;

你能帮帮我吗？谢谢。

Answer 1

语句"DescribeStreamOutcome is defined in DynamoDBStreamsClient.h“不正确。DynamoDBStreamsClient.h中的那一行定义了结果实例化的别名。

clang给出了更简洁的错误消息：

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，但只要不调用任何返回结果的方法，使用DynamoDBStreamsClient的代码就可以在没有它的情况下编译。