DescribeStreamOutcome reported as "incomplete type"

Question

I cloned aws-sdk-cpp from github and I managed to build it without problems (tests passed as well). I did not do "make install". I wanted to compile the dynamodbstreams part of the SDK exclusively, so I added -DBUILD_ONLY="dynamodbstreams" to the cmake parameters. I wrote a small test code, but it fails to compile because of the DescribeStreamOutcome type that is reported to be undefined ("inclomplete type"). However, it exists in the header file where it ought to be.

cmake version: 3.5.1, g++ version: 5.4.0 (I did not tried clang so far)

Could anyone please look at the codes and point out what's wrong?

I have the following code:

#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;
}

With this 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

Upon making I get the following error:

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

However, DescribeStreamOutcome is defined in DynamoDBStreamsClient.h:

$ 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;

So could you please help me out? Thanks.

Bulletmagnet · Answer 1 · 2017-12-04T14:23:27.563

The statement "DescribeStreamOutcome is defined in DynamoDBStreamsClient.h" is incorrect. That line in DynamoDBStreamsClient.h defines an alias to an instantiation of Outcome.

clang gives a somewhat more concise error message:

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;
                                          ^

You need to #include "aws/core/utils/Outcome.h"

Perhaps aws/dynamodbstreams/DynamoDBStreamsClient.h should have included Outcome.h, although code using DynamoDBStreamsClient compiles without it, as long as you don't call any of the Outcome-returning methods.

DescribeStreamOutcome reported as "incomplete type"

1 Answers1