AVRO-3616: C++ Fix compilation warnings

[martin-g]

Jira

• https://issues.apache.org/jira/browse/AVRO-3616

Tests

• My PR updates existing unit tests

Commits

• My commits all reference Jira issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• No need

[KalleOlaviNiemitalo]

Better use size_t, because Node::leaves returns size_t, and Node::leafAt takes a size_t parameter. Or perhaps decltype(leaves).

[KalleOlaviNiemitalo]

On 64-bit Microsoft Windows, size_t is 64-bit, but long unsigned int is 32-bit and would not be pedantically correct. In practice though, it's rather unlikely that a node would have billions of leaves.

[martin-g]

Improved! Thanks!

[KalleOlaviNiemitalo]

In Validator, there seems to be some inconsistency with std::vector<size_t> counters_ and int64_t count_, too:

• Validator::countingSetup converts int64_t to size_t: counters_.push_back(static_cast<size_t>(count_));
• Validator::countingAdvance converts size_t to int: int count = --counters_.back();
• Validator::unionAdvance converts size_t to int64_t: if (count_ < static_cast<int64_t>(node->leaves()))
• Validator::unionAdvance converts int64_t to int and that to size_t: setupOperation(node->leafAt(static_cast<int>(count_)));

Those could be fixed in a separate PR, though.

[martin-g]

In Validator, there seems to be some inconsistency with

How did you find those ?
By looking in the code or by using some tool ?

[KalleOlaviNiemitalo]

I worried that commit e632e65 changing the types of the local variables to size_t in might cause problems if any subsequent code tries to use negative values in those variables. I looked at the remaining parts of the modified methods and did not find any such problems, but found the int count = --counters_.back() assignment in Validator::countingAdvance. That seemed suspicious to me, so I searched for other uses of counters_ and count_ in the Validator files. I didn't even use an IDE, just a Web browser.

[martin-g]

Thanks, @KalleOlaviNiemitalo !
I will leave this for a separate ticket/PR.

[KalleOlaviNiemitalo]

I filed those as AVRO-3617.