[
https://issues.apache.org/jira/browse/ARROW-17408?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17580127#comment-17580127
]
Xuwei Fu commented on ARROW-17408:
----------------------------------
[~apitrou] Hi, mind take a look? My fixing works for C++20, but would not
compile in some platforms. Should I add some macros that make it only works in
C++20?
> C++20 compile arrow get `operator==` ambiguous
> ----------------------------------------------
>
> Key: ARROW-17408
> URL: https://issues.apache.org/jira/browse/ARROW-17408
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Affects Versions: 9.0.0
> Reporter: Xuwei Fu
> Priority: Trivial
> Labels: pull-request-available
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> When compiling arrow-9.0.0 in C++20, I got:
>
> ```
> In file included from ../arrow/cpp/src/arrow/ipc/dictionary.cc:32:
> ../arrow/cpp/src/arrow/record_batch.h:266:21: warning: ISO C++20 considers
> use of overloaded operator '==' (with operand types 'const
> Result<std::shared_ptr<RecordBatch>>' and 'const
> Result<std::shared_ptr<RecordBatch>>') to be ambiguous despite there being a
> unique best viable function [-Wambiguous-reversed-operator]
> return batch_ == other.batch_;
> ~~~~~~ ^ ~~~~~~~~~~~~
> ../arrow/cpp/src/arrow/util/compare.h:54:8: note: ambiguity is between a
> regular call to this operator and a call with the argument order reversed
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ^
> In file included from ../arrow/cpp/src/arrow/ipc/dictionary.cc:18:
> In file included from ../arrow/cpp/src/arrow/ipc/dictionary.h:27:
> ../arrow/cpp/src/arrow/result.h:278:20: warning: ISO C++20 considers use of
> overloaded operator '==' (with operand types 'const arrow::Status' and 'const
> arrow::Status') to be ambiguous despite there being a unique best viable
> function [-Wambiguous-reversed-operator]
> return status_ == other.status_;
> ~~~~~~~ ^ ~~~~~~~~~~~~~
> ../arrow/cpp/src/arrow/util/compare.h:54:57: note: in instantiation of member
> function 'arrow::Result<std::shared_ptr<arrow::RecordBatch>>::Equals'
> requested here
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ^
> ../arrow/cpp/src/arrow/record_batch.h:266:21: note: in instantiation of
> member function
> 'arrow::util::EqualityComparable<arrow::Result<std::shared_ptr<arrow::RecordBatch>>>::operator=='
> requested here
> return batch_ == other.batch_;
> ^
> ../arrow/cpp/src/arrow/util/compare.h:54:8: note: ambiguity is between a
> regular call to this operator and a call with the argument order reversed
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ^
> 2 warnings generated.
> In file included from ../arrow/cpp/src/arrow/ipc/message.cc:33:
> In file included from ../arrow/cpp/src/arrow/ipc/reader.h:32:
> ../arrow/cpp/src/arrow/record_batch.h:266:21: warning: ISO C++20 considers
> use of overloaded operator '==' (with operand types 'const
> Result<std::shared_ptr<RecordBatch>>' and 'const
> Result<std::shared_ptr<RecordBatch>>') to be ambiguous despite there being a
> unique best viable function [-Wambiguous-reversed-operator]
> return batch_ == other.batch_;
> ~~~~~~ ^ ~~~~~~~~~~~~
> ../arrow/cpp/src/arrow/util/compare.h:54:8: note: ambiguity is between a
> regular call to this operator and a call with the argument order reversed
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ^
> In file included from ../arrow/cpp/src/arrow/ipc/message.cc:18:
> In file included from ../arrow/cpp/src/arrow/ipc/message.h:30:
> ../arrow/cpp/src/arrow/result.h:278:20: warning: ISO C++20 considers use of
> overloaded operator '==' (with operand types 'const arrow::Status' and 'const
> arrow::Status') to be ambiguous despite there being a unique best viable
> function [-Wambiguous-reversed-operator]
> return status_ == other.status_;
> ~~~~~~~ ^ ~~~~~~~~~~~~~
> ../arrow/cpp/src/arrow/util/compare.h:54:57: note: in instantiation of member
> function 'arrow::Result<std::shared_ptr<arrow::RecordBatch>>::Equals'
> requested here
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ^
> ../arrow/cpp/src/arrow/record_batch.h:266:21: note: in instantiation of
> member function
> 'arrow::util::EqualityComparable<arrow::Result<std::shared_ptr<arrow::RecordBatch>>>::operator=='
> requested here
> return batch_ == other.batch_;
> ^
> ../arrow/cpp/src/arrow/util/compare.h:54:8: note: ambiguity is between a
> regular call to this operator and a call with the argument order reversed
> bool operator==(const T& other) const \{ return cast().Equals(other); }
> ```
>
> Generate or hand written `operator==` for `Result` maybe fixing this problem.
> Seems problems cames from:
> https://stackoverflow.com/questions/65833022/inherited-synthesized-comparison-operator-produces-warning-error-iso-c20-cons
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
