Looks like there is a relation between creating a cc_library on a BUILD file using hdrs and includes to generate the gcc command with -isystem, -iquote and -I.
To explain my problem better, I have this example.
I have a Bazel project with the following files:
The dependencies are:
main.cpp needs foo.hppfoo.hpp needs access to #include "bar.h", so a library hdrs-bar is providedbar.h needs access to #include <system_bar.h>, so a library hdrs-system-bar is provided. (Note that <> on the include is needed.)demo is created with all these dependenciesAs described on (1), the main.cpp contains:
#include "foo.hpp"
int main()
{
// ...something which uses foo.hpp
return 0;
}
As described on (2), to be able to access foo.hpp from main.cpp I need to create a Bazel project out of a git repository and create a BUILD file for for it using the build_file_content where it contains a library that will expose all the *.h files I need (including the bar.h).
Therefore the WORKSPACE file contains:
load("@bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
new_git_repository(
name = "bar-utils",
remote = "https://github.com/someGitRepo/bar-utils.git",
branch = "master",
build_file_content = """
package(default_visibility = ["//visibility:public"])
cc_library(
name = "hdrs-bar",
hdrs = glob(["bar/*.h"], allow_empty=False),
strip_include_prefix = "bar",
)
""",
)
As described on (3), the WORKSPACE file also contains a creation of a library called hdrs-system-bar which contains the system headers needed from bar.h:
new_local_repository(
name = "bar-system",
path = "/usr/local/bar/include",
build_file_content = """
cc_library(
name = "hdrs-system-bar",
hdrs = glob(["*.h"], allow_empty=False),
visibility = ["//visibility:public"],
)
""",
)
As described in (4), the BUILD file contains a binary which gets all the dependencies in deps:
cc_binary(
name = "demo",
srcs = ["main.cpp"],
deps = ["@bar-utils//:hdrs-bar", "@bar-system//:hdrs-system-bar"],
)
If I compile:
$ bazel build //... --sandbox_debug
I get the following build ERROR:
bazel-out/aarch64-fastbuild/bin/external/bar-utils/_virtual_includes/hdrs-bar/barUtils.h:7:10: fatal error: bar_runtime.h: No such file or directory #include <bar_runtime.h>
The file bar_runtime.h should be inside the library hdrs-system-bar.
So if I see my sandbox folder on .../sandbox/linux-sandbox/4/execroot/__main__/ I get the following directories:
On the external, I have these two folder, where each contains all the header files I need:
On the bazel-out, I have the following:
aarch64-fastbuild/bin/external/bar-utils/_virtual_includes/hdrs-bar/bar.h
I was expecting inside this bazel-out external to have also the bar-system, but there is only bar-utils. Why is that?
To add more info the gcc command generated was like this (removed all the non-necessary arguments for sake of simplicity):
/usr/bin/gcc -iquote external/bar-utils -iquote external/bar-system -c main.cpp
If I simply use includes instead of hdrs on all the libraries creation, I get a lot of -isystem instead of the -iquote. But what I need is actually the -I<folder where the headers are>.
If I manually change my gcc command to:
/usr/bin/gcc -iquote external/bar-utils -Iexternal/bar-system -c main.cpp
Then it works.
How can I force it to use -I? Changing the cc_libraries to srcs or includes instead of hdrs is not working.
Solution is to also use the includes flag, besides the hdrs. This way it will show up on the sandbox and be accessible by adding the -isystem argument for gcc with the folder you need.
cc_library(
name = "hdrs-system-bar",
hdrs = glob(["*.h"], allow_empty=False),
includes = ["."],
visibility = ["//visibility:public"],
)