[C++] Rare bad buffer content alignment if sizeof(T) != alignof(T)

[Naios]

EDIT: Fix for #7516, see below

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[tungmeoo]

ok

[Naios]

@dbaileychess Could you review this PR please?

I fixed the issue by adding alignment parameters to functions calling StartVector.

Additionally, I spotted several expressions in the codebase of the form array_length = len * sizeof(T) / AlignOf<T>() that do not seem right to me and might need a correction.

[dbaileychess]

@Naios You need to add your new file to the bazel build rule, its failing CI: https://github.com/google/flatbuffers/blob/master/tests/BUILD.bazel#L7

[dbaileychess]

Generally looks good to me.

[Naios]

@dbaileychess Thank you for your review, I have fixed the outstanding changes and optimizations.

[Naios]

@dbaileychess From my side this PR is finished, do you know why workflow "buildkite/flatbuffers/pr" is failing without any useful output?

[dbaileychess]

Build kite error:

:bazel: buildifier: found 1 format issue in your WORKSPACE, BUILD and *.bzl files
Please download [buildifier 5.1.0](https://github.com/bazelbuild/buildtools/releases/tag/5.1.0) and run the following command in your workspace:

buildifier tests/BUILD.bazel

Looks like you placed the deps out of alphanumeric order.

[dbaileychess]

The fuzzer build is failing too, looks like due to stricter warnings on the deprecated method. Can you see if the deprecated method is being used in the fuzzer to fix it?

[Naios]

@dbaileychess I probably have fixed the remaining issues, could you approve the outstanding workflows again please?

[dbaileychess]

Thanks a bunch!