Andrew Peter Marlow created AVRO-3705:
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Summary: avrogencpp needs an option to generate code using std
instead of boost
Key: AVRO-3705
URL: https://issues.apache.org/jira/browse/AVRO-3705
Project: Apache Avro
Issue Type: Improvement
Components: c++
Affects Versions: 1.11.0
Environment: RHEL8. The gcc installed from the Red Hat repo is version
8.5.0 which has an option to use c++17 since that dialect is not the default.
The avro-cpp package in the Red Hat repo must have been built with that since
it emits code that uses boost.
Reporter: Andrew Peter Marlow
avrogencpp uses either std or boost in the generated code. It does this
depending on how it was built, using #if __cplusplus >= 201703L. If the
compiler supports std::any then it used, otherwise boost is used. The
assumption is that if the compiler used to build avrogencpp supports C++17 by
default then emitted code can use C++17 otherwise the emitted code should use
boost. This assumption turns out to have a weakness - if a project uses a
compiler where C++17 is given as an option because it is not the default then
the code avrogencpp generates will use boost instead of std.
This problem could be solved if avrogencpp supported a command line option to
use c++17. The option could be used by those environments where avrogencpp was
built with a version of gcc that does not support c++17 by default but the
desire is to use C++17.
This is a serious need because there is a significant difference between
boost::any and std::any. The standard any has a small buffer optimisation but
boost does not. This means that code generated by avrogencpp that uses
boost::any will use heap memory for every case where the generated code uses
the any type. This could be avoided if the c++17 was available.
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