Could you have an cpp example that shows #include headers from other directories?

[ninechapters]

Case 1:
foopath/foo.cpp needs to include barpath/bar.h

How do I describe the dependency here?

Case 2:
What about second level header file inclusion? For example
foopath/foo.cpp needs to include barpath/bar.h, which includes bazpath/baz.h

[cgrushko]

My cc_library-knowledge is rusty, so I might be wrong, but -

###Case 1

If you have one BUILD file in ., you can just reference the sub-directories like this:

cc_library(
  name = "foo",
  srcs = ["foopath/foo.cpp"],
  hdrs = ["barpath/bar.h"],
)

If you have two BUILD files, one in foopath/ and the other in barpath/, you can do something like

cc_library(
  name = "foo",
  srcs = ["foo.cpp"],
  deps = ["//root/to/barpath:bar"],
)

//root/to/barpath:bar must be a cc_library, which must have a srcs attribute.

###Case 2

You can include more than one header,

cc_library(
  name = "foo",
  srcs = ["foopath/foo.cpp"],
  hdrs = ["barpath/bar1.h", "barpath/bar2.h"],
)

[davidzchen]

From the Build Encyclopedia section on cc_library:

hdrs: The list of header files published by this library to be directly included by sources in dependent rules.

Thus, in your case, you should do the following:

In barpath/, define a cc_library target for the bar.cpp source file that publishes the bar.h header file via hdrs:

cc_library(
    name = "bar",
    srcs = ["bar.cpp"],
    hdrs = ["bar.h"],
)

And then in foopath/foo.cpp, you would have the following #include:

#include "barpath/bar.h"
...

And then define the build rule under foopath/ for foo.cpp with a dependency on //barpath:bar:

cc_library(
    name = "foo",
    srcs = ["foo.cpp"],
    hdrs = ["foo.h"],
    deps = ["//barpath:bar"],
)

Basically, use hdrs to indicate which header files //barpath:bar publishes, and use deps to indicate that //foopath:foo depends on //barpath:bar. Bazel will then the hdrs from //barpath:bar to include the correct header files when building //foopath:foo.

[davidzchen]

For the case where you have foopath/foo.cpp including barpath/bar.h which includes bazpath/baz.h, you will just have three targets where //foopath:foo depends on //barpath:bar which depends on //bazpath:baz, similar to the following:

Under bazpath/:

cc_library(
    name = "baz",
    srcs = ["baz.cpp"],
    hdrs = ["baz.h"],
    deps = [...],
)

Under barpath/:

cc_library(
    name = "bar",
    srcs = ["bar.cpp"],
    hdrs = ["bar.h"],
    deps = [
        "//bazpath:baz",
        ...
    ],
)

And finally, under foopath/:

cc_library(
    name = "foo",
    srcs = ["foo.cpp"],
    hdrs = ["foo.h"],
    deps = [
        "//barpath:bar",
    ],
)

[damienmg]

I haven't found a documentation label but we should have such an example