Are cc_library hdrs irrelevant in Bazel 4.0?

[carpen...@gmail.com]

Hi, 

With Bazel 4.0 if I have two cc_library(s) (A->B), but no where do I export any headers. Then I do I expect a warning to say that you haven't got a dependency on that header anymore, or has is the hdrs declaration of a public interface now obsolete? 

This is a minimal example:

A\BUILD

```

cc_library(

    name="a",

    srcs=["final.cpp"],

    deps=[

        "//b"

    ]

)

```

A\final.cpp

```

#include "b/item.h"

```

B\BUILD 

```

load("@rules_cc//cc:defs.bzl", "cc_library")

cc_library(

    name = "b",

    srcs = [

        "item.cpp",

        "item.h",

    ],

    visibility = ["//visibility:public"],

)

```

B/item.h 

```

```

B/item.cpp

```

#include "item.h"

```

I expect to get a warning as this is not a declared header, but instead it seems to work fine.

Does bazel now track these files? 

Will A be guaranteed to rebuild when you have reproducible builds and the B/B.lib is the same checksum, even if `B/item.h` changes checksum?

Thanks

James

[Tobias Werth]

+Pedro Liberal Fernandez 

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[p...@google.com]

Which header is undeclared? The only header I see is declared in "b" and that is available to "a".

[carpen...@gmail.com]

"B/item.h" is undeclared and is available to B only according to the documentation as its a private header. I don't have anything in the  hdrs section of B.

If I put no dependency between A and B then it fails the header inclusion check, but not when A uses a private header of B. 

[Xavier Bonaventura]

Hi James,

I think what you describe is exactly what is being discussed in this ticket

https://github.com/bazelbuild/bazel/issues/6615

Bests,

Xavi