pw_build: Support pw_facade without public headers
- Allow use of pw_facade without public headers, but do not emit a
.facade subtarget when it is empty. pw_facade still provides value
since it handles unset backend variables and gives helpful errors.
- Propagate visibility to the ".facade" target. Fix existing visibility
violations.
Change-Id: I2e64feb241979fbf3aa5a37d4c6bbfe07aaa18f1
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/239755
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Commit-Queue: Wyatt Hepler <hepler@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
diff --git a/pw_build/facade.gni b/pw_build/facade.gni
index a823360..e3c1bc0 100644
--- a/pw_build/facade.gni
+++ b/pw_build/facade.gni
@@ -79,18 +79,21 @@
template("pw_facade") {
assert(defined(invoker.backend),
"pw_facade requires a reference to a backend variable for the facade")
- assert(defined(invoker.public),
- "If your facade does not explicitly expose an API that a backend " +
- "must depend on, you can just directly depend on the build arg " +
- "that the `backend` template argument would have been set to.")
- _facade_name = "$target_name.facade"
+ # Only define the .facade subtarget if it has a public attribute to share.
+ if (defined(invoker.public) || defined(invoker.public_deps) ||
+ defined(invoker.public_configs)) {
+ _facade_name = "$target_name.facade"
- if (get_path_info(get_label_info(":$target_name", "dir"), "name") ==
- get_label_info(":$target_name", "name")) {
- group("facade") {
- public_deps = [ ":$_facade_name" ]
+ # Define //foo:facade alias
+ if (get_path_info(get_label_info(":$target_name", "dir"), "name") ==
+ get_label_info(":$target_name", "name")) {
+ group("facade") {
+ public_deps = [ ":$_facade_name" ]
+ }
}
+ } else {
+ _facade_name = ""
}
_facade_vars = [
@@ -100,9 +103,12 @@
"public_configs",
"public_deps",
"public",
+ "visibility",
]
- pw_source_set(_facade_name) {
- forward_variables_from(invoker, _facade_vars, [ "require_link_deps" ])
+ if (_facade_name != "") {
+ pw_source_set(_facade_name) {
+ forward_variables_from(invoker, _facade_vars, [ "require_link_deps" ])
+ }
}
if (invoker.backend == "") {
@@ -158,14 +164,16 @@
]
forward_variables_from(invoker, "*", _ignore_vars)
- public_deps = [ ":$_facade_name" ]
-
# If the backend is set, inject it as a dependency.
if (invoker.backend != "") {
- public_deps += [ invoker.backend ]
+ public_deps = [ invoker.backend ]
} else {
# If the backend is not set, depend on the *.NO_BACKEND_SET target.
- public_deps += [ ":$target_name.NO_BACKEND_SET" ]
+ public_deps = [ ":$target_name.NO_BACKEND_SET" ]
+ }
+
+ if (_facade_name != "") {
+ public_deps += [ ":$_facade_name" ]
}
}
@@ -183,11 +191,11 @@
}
}
- _facade_name = get_label_info(":$target_name", "label_no_toolchain")
+ _facade = get_label_info(":$target_name", "label_no_toolchain")
assert(_dep_is_in_link_dependencies,
"$_required_dep must be listed in the pw_build_LINK_DEPS build " +
- "arg when the $_facade_name facade is in use. Please update " +
- "your toolchain configuration.")
+ "arg when the $_facade facade is in use. Please update your " +
+ "toolchain configuration.")
}
} else {
not_needed(invoker, [ "require_link_deps" ])
diff --git a/pw_build/gn.rst b/pw_build/gn.rst
index fd20c96..31f5aa5 100644
--- a/pw_build/gn.rst
+++ b/pw_build/gn.rst
@@ -378,12 +378,14 @@
This allows the facade to provide header files, compilation options or anything
else a GN ``source_set`` provides.
-The ``pw_facade`` template declares two targets:
+The ``pw_facade`` template declares one or two targets:
-* ``$target_name``: the public-facing ``pw_source_set``, with a ``public_dep``
- on the backend
-* ``$target_name.facade``: target used by the backend to avoid circular
- dependencies
+* ``$target_name``: The public-facing ``pw_source_set``, with a ``public_dep``
+ on the backend. Always declared.
+* ``$target_name.facade``: Target with ``public`` headers, ``public_deps``, and
+ ``public_configs`` shared between the public-facing ``pw_source_set`` and
+ backend to avoid circular dependencies. Only declared if ``public``,
+ ``public_deps``, or ``public_configs`` are provided.
.. code-block::
diff --git a/pw_sync/BUILD.gn b/pw_sync/BUILD.gn
index 235d8b6..0f20710 100644
--- a/pw_sync/BUILD.gn
+++ b/pw_sync/BUILD.gn
@@ -131,7 +131,11 @@
"$dir_pw_preprocessor",
]
sources = [ "recursive_mutex.cc" ]
- visibility = [ ":*" ]
+ visibility = [
+ ":*",
+ "$dir_pw_sync_baremetal/*",
+ "$dir_pw_sync_stl/*",
+ ]
}
pw_facade("interrupt_spin_lock") {
