skia2/bazel/macros.bzl
Kevin Lubick e253cc3e55 [bazel] Use toolchain features to opt files into being IWYU compliant.
PS1 regenerates the Bazel files.

It is recommended to review this CL with a diff from PS1.

Example output when a file does not pass the test:
    tools/sk_app/CommandSet.h should add these lines:
    #include "include/core/SkTypes.h"
    #include "include/private/SkTArray.h"
    #include "tools/skui/InputState.h"
    #include "tools/skui/Key.h"
    #include "tools/skui/ModifierKey.h"
    namespace sk_app { class Window; }

    tools/sk_app/CommandSet.h should remove these lines:
    - #include "tools/sk_app/Window.h"

    The full include-list for tools/sk_app/CommandSet.h:
    #include "include/core/SkString.h"
    #include "include/core/SkTypes.h"
    #include "include/private/SkTArray.h"
    #include "tools/skui/InputState.h"
    #include "tools/skui/Key.h"
    #include "tools/skui/ModifierKey.h"
    #include <functional>
    #include <vector>
    class SkCanvas;
    namespace sk_app { class Window; }
    ---

This makes use of Bazel's toolchain features
https://bazel.build/docs/cc-toolchain-config-reference#features
to allow us to configure compiler flags when compiling
individual files. This analysis is off by default, and can
be turned on with --features skia_enforce_iwyu. When enabled,
it will only be run for files that have opted in.
Example:
    bazelisk build //example:hello_world_gl --config=clang \
       --sandbox_base=/dev/shm --features skia_enforce_iwyu

There are two ways to opt files in:
 - Add enforce_iwyu = True to a generated_cc_atom rule
 - Add enforce_iwyu_on_package() to a BUILD.bazel file
   (which enforces IWYU for all rules in that file)

Note that Bazel does not propagate features to dependencies
or dependents, so trying to enable the feature on cc_library
or cc_executable targets will only impact any files listed in
srcs or hdrs, not deps. This may be counter-intuitive when
compared to things like defines.

IWYU supports a mapping file, which we supply to help properly
handle things system headers (//toolchain/IWYU_mapping.imp)

Suggested Review Order:
 - toolchain/build_toolchain.bzl to see how we get the IWYU
   binaries into the toolchain
 - toolchain/BUILD.bazel and toolchain/IWYU_mapping.imp
   to see how the mapping file is made available for
   all compile steps
 - toolchain/clang_toolchain_config.bzl, where we define the
   skia_enforce_iwyu feature to turn on any verification at
   all and skia_opt_file_into_iwyu to enable the check for
   specific files using a define.
 - toolchain/clang_trampoline.sh, which is the toolchain is
   configured to call instead of clang directly (see line 83
   of clang_toolchain_config.bzl). This bash script used to
   just forward all arguments directly onto clang. Now it
   inspects them and either calls clang directly (if
   it does not find the define in the arguments or we are
   linking [bazel sometimes links with clang instead of ld])
   or calls clang and then include-what-you-use. In all cases,
   the trampoline sends the arguments to clang and IWYU
   unchanged).
 - //tools/sk_app/... to see enforcement enabled (and fixed)
   for select files, as an example of that method.
 - //experimental/bazel_test/... to see enforcement enabled
   for all rules in a BUILD.bazel file.
 - all other files.

Change-Id: I60a2ea9d5dc9955b6a8f166bd449de9e2b81a233
Bug: skia:13052
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/519776
Reviewed-by: Ben Wagner <bungeman@google.com>
Reviewed-by: Leandro Lovisolo <lovisolo@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
2022-03-16 13:09:46 +00:00

85 lines
3.4 KiB
Python

"""
This file contains general helper macros that make our BUILD.bazel files easier to read.
"""
def select_multi(values_map, default, name = ""):
"""select() but allowing multiple matches of the keys.
select_multi works around a restriction in native select() that prevents multiple
keys from being matched unless one is a strict subset of another. For some features,
we allow multiple of that component to be active. For example, with codecs, we let
the clients mix and match anywhere from 0 built in codecs to all of them.
select_multi takes a given map and turns it into several distinct select statements
that have the effect of using any values associated with any active keys.
For example, if the following parameters are passed in:
values_map = {
":alpha": ["apple", "apricot"],
":beta": ["banana"],
":gamma": ["grapefruit"],
},
default = []
it will be unrolled into the following select statements
[] + select({
":apple": ["apple", "apricot"],
"//conditions:default": [],
}) + select({
":beta": ["banana"],
"//conditions:default": [],
}) + select({
":gamma": ["grapefruit"],
"//conditions:default": [],
})
Args:
values_map: dictionary of labels to a list of labels, just like select()
default: list of labels, the value that should be used if any of the options do not match.
This is typically an empty list
name: string unused, https://github.com/bazelbuild/buildtools/blob/master/WARNINGS.md#unnamed-macro
Returns:
A list of values that is filled in by the generated select statements.
"""
if len(values_map) == 0:
return default
rv = []
for key, value in values_map.items():
rv += select({
key: value,
"//conditions:default": default,
})
return rv
def generated_cc_atom(name, enforce_iwyu = False, **kwargs):
"""A self-annotating label for a generated cc_library for exactly one file.
Args:
name: string, the name of the cc_library
enforce_iwyu: boolean, if true, this file will fail to compile if the headers to not comply
with the include-what-you-use standards. This does not affect dependencies nor
dependents, only the file listed in srcs/hdrs.
**kwargs: All other arguments are passed verbatim to cc_library
"""
if len(kwargs.get("srcs", [])) > 1 or len(kwargs.get("hdrs", [])) > 1:
fail("Cannot have more than one src or hdr file in generated_cc_atom")
if len(kwargs.get("srcs", [])) > 0 and len(kwargs.get("hdrs", [])) > 0:
fail("Cannot set both srcs and hdrs in generated_cc_atom")
if len(kwargs.get("srcs", [])) == 0 and len(kwargs.get("hdrs", [])) == 0:
fail("Must set exactly one of srcs or hdrs in generated_cc_atom")
deps = kwargs.get("deps", [])
deps.append("//bazel:defines_from_flags")
kwargs["deps"] = deps
features = kwargs.get("features", [])
if enforce_iwyu:
features.append("skia_opt_file_into_iwyu")
native.cc_library(
name = name,
features = features,
**kwargs
)
def enforce_iwyu_on_package():
"""A self-annotating macro to set force_iwyu = True on all rules in this package."""
native.package(features = ["skia_opt_file_into_iwyu"])