search

google / styleguide

Style guides for Google-originated open-source projects
https://google.github.io/styleguide/
Apache License 2.0
37.55k stars 13.3k forks source link

Contradiction between C++ styleguide and cpplint regarding transitive includes #757

Open geoffviola opened 1 year ago

geoffviola commented 1 year ago

This issue comes from https://github.com/cpplint/cpplint/issues/218

The Google C++ Style Guide states that

Do not rely on transitive inclusions. This allows people to remove no-longer-needed #include statements from their headers without breaking clients. This also applies to related headers - foo.cc should include bar.h if it uses a symbol from it even if foo.h includes bar.h.

The second part about including the direct dependencies in the source file regardless of the corresponding header, contradicts with cpplint. When cpplint is run on a source file, it counts the includes in its corresponding header file as included.

The policy is that if you #include something in foo.h you don't need to include it again in foo.cc. Here, we will look at possible includes.

Which rule should be followed?

tituswinters commented 1 year ago

It's easier for IDEs and other tools to follow the simpler rule in the style guide ("is this symbol provided by a file #included directly in this file?"), so we'd prefer the written rule not the legacy behavior in cpplint.

On Sun, Jan 29, 2023 at 11:42 AM Geoffrey Viola @.***> wrote:

This issue comes from cpplint#218 https://github.com/cpplint/cpplint/issues/218

The Google C++ Style Guide https://google.github.io/styleguide/cppguide.html#Include_What_You_Use states that

Do not rely on transitive inclusions. This allows people to remove no-longer-needed #include statements from their headers without breaking clients. This also applies to related headers - foo.cc should include bar.h if it uses a symbol from it even if foo.h includes bar.h.

The second part about including the direct dependencies in the source file regardless of the corresponding header, contradicts with cpplint. When cpplint https://github.com/cpplint/cpplint/blob/fa12a0bbdafa15291276ddd2a2dcd2ac7a2ce4cb/cpplint.py#L6127-L6128 is run on a source file, it counts the includes in its corresponding header file as included.

The policy is that if you #include something in foo.h you don't need to include it again in foo.cc. Here, we will look at possible includes.

Which rule should be followed?

— Reply to this email directly, view it on GitHub https://github.com/google/styleguide/issues/757, or unsubscribe https://github.com/notifications/unsubscribe-auth/AC7CRX6C42IQPX2WOPDCO53WU2MYVANCNFSM6AAAAAAUKKXV4Q . You are receiving this because you are subscribed to this thread.Message ID: @.***>

-- If you get an email from me outside of the 9-5 it is not* because I'm always on or expect an immediate response from you; it is because of work flexibility http://www.inc.com/john-boitnott/how-flexible-hours-can-create-a-better-work-life-balance.html . Evening and weekend emails are a sign I allocated some regular working hours for other things (such as family, gym, friends,...). And I encourage you to feel free to do the same.