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The size/1 BIF is not optimized by the JIT, and its use can result in worse types for Dialyzer.

When one knows that the value being tested must be a tuple, tuple_size/1 should always be preferred.

When one knows that the value being tested must be a binary, byte_size/1 should be preferred. However, byte_size/1 also accepts a bitstring (rounding up size to a whole number of bytes), so one must make sure that the call to byte_size/ is preceded by a call to is_binary/1 to ensure that bitstrings are rejected. Note that the compiler removes redundant calls to is_binary/1, so if one is not sure whether previous code had made sure that the argument is a binary, it does not harm to add an is_binary/1 test immediately before the call to byte_size/1.

This PR extends #6770 simply in the branch naming convention. No changes in the implementation

The <c>size/1</c> BIF is not optimized by the JIT, and its use can
result in worse types for Dialyzer.

When one knows that the value being tested must be a tuple,
<c>tuple_size/1</c> should always be preferred.

When one knows that the value being tested must be a binary,
<c>byte_size/1</c> should be preferred. However, <c>byte_size/1</c> also
accepts a bitstring (rounding up size to a whole number of bytes), so
one must make sure that the call to <c>byte_size/</c> is preceded by a
call to <c>is_binary/1</c> to ensure that bitstrings are rejected. Note
that the compiler removes redundant calls to <c>is_binary/1</c>, so if
one is not sure whether previous code had made sure that the argument is
a binary, it does not harm to add an <c>is_binary/1</c> test immediately
before the call to <c>byte_size/1</c>.
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github-actions bot commented Feb 6, 2023

CT Test Results

Tests are running... https://github.com/erlang/otp/actions/runs/4101317794

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// Erlang/OTP Github Action Bot

@kikofernandez kikofernandez merged commit 8b7906c into erlang:maint Feb 6, 2023
@kikofernandez kikofernandez deleted the kiko/ftp/replace-size-by-xxx_size/GH-6672/OTP-18432 branch February 6, 2023 08:44
kikofernandez added a commit to kikofernandez/otp that referenced this pull request Feb 9, 2023
this commit fixes a mistake in erlangGH-6793 where a guard was removed.
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