Add os/target configurable selects for label list attributes.
This CL is pretty large, so I recommend starting with reading the newly
added tests for the expected behavior.
This change works in conjunction with the linked CLs in the Gerrit topic.
Those CLs add support for new platform() definitions for OS targets
specified in Soong's arch.go, which are configurable through
Android.bp's `target {}` property. It works similary to previous CLs
adding support for the `arch {}` property.
These configurable props are keyed by the OS: android, linux_bionic,
windows, and so on. They map to `select` statements in label list
attributes, which this CL enables for cc_library_headers' header_libs
and export_header_lib_headers props.
This enables //bionic/libc:libc_headers to be generated correctly, from:
cc_library_headers {
name: "libc_headers",
target: {
android: {
header_libs: ["libc_headers_arch"],
export_header_lib_headers: ["libc_headers_arch"],
},
linux_bionic: {
header_libs: ["libc_headers_arch"],
export_header_lib_headers: ["libc_headers_arch"],
},
},
// omitted props
}
to:
cc_library_headers(
name = "libc_headers",
deps = [] + select({
"//build/bazel/platforms/os:android": [
":libc_headers_arch",
],
"//build/bazel/platforms/os:linux_bionic": [
":libc_headers_arch",
],
"//conditions:default": [],
}),
)
Test: TH
Test: Verify generated //bionic/libc:libc_headers
Fixes: 183597786
Change-Id: I01016cc2cc9a71449f02300d747f01decebf3f6e
diff --git a/android/arch.go b/android/arch.go
index 20b4ab0..3eff5d5 100644
--- a/android/arch.go
+++ b/android/arch.go
@@ -1709,3 +1709,90 @@
}
return archToProp
}
+
+// GetTargetProperties returns a map of OS target (e.g. android, windows) to the
+// values of the properties of the 'dst' struct that are specific to that OS
+// target.
+//
+// For example, passing a struct { Foo bool, Bar string } will return an
+// interface{} that can be type asserted back into the same struct, containing
+// the os-specific property value specified by the module if defined.
+//
+// While this looks similar to GetArchProperties, the internal representation of
+// the properties have a slightly different layout to warrant a standalone
+// lookup function.
+func (m *ModuleBase) GetTargetProperties(dst interface{}) map[OsType]interface{} {
+ // Return value of the arch types to the prop values for that arch.
+ osToProp := map[OsType]interface{}{}
+
+ // Nothing to do for non-OS/arch-specific modules.
+ if !m.ArchSpecific() {
+ return osToProp
+ }
+
+ // archProperties has the type of [][]interface{}. Looks complicated, so
+ // let's explain this step by step.
+ //
+ // Loop over the outer index, which determines the property struct that
+ // contains a matching set of properties in dst that we're interested in.
+ // For example, BaseCompilerProperties or BaseLinkerProperties.
+ for i := range m.archProperties {
+ if m.archProperties[i] == nil {
+ continue
+ }
+
+ // Iterate over the supported OS types
+ for _, os := range OsTypeList {
+ // e.g android, linux_bionic
+ field := os.Field
+
+ // If it's not nil, loop over the inner index, which determines the arch variant
+ // of the prop type. In an Android.bp file, this is like looping over:
+ //
+ // target: { android: { key: value, ... }, linux_bionic: { key: value, ... } }
+ for _, archProperties := range m.archProperties[i] {
+ archPropValues := reflect.ValueOf(archProperties).Elem()
+
+ // This is the archPropRoot struct. Traverse into the Targetnested struct.
+ src := archPropValues.FieldByName("Target").Elem()
+
+ // Step into non-nil pointers to structs in the src value.
+ if src.Kind() == reflect.Ptr {
+ if src.IsNil() {
+ continue
+ }
+ src = src.Elem()
+ }
+
+ // Find the requested field (e.g. android, linux_bionic) in the src struct.
+ src = src.FieldByName(field)
+
+ // Validation steps. We want valid non-nil pointers to structs.
+ if !src.IsValid() || src.IsNil() {
+ continue
+ }
+
+ if src.Kind() != reflect.Ptr || src.Elem().Kind() != reflect.Struct {
+ continue
+ }
+
+ // Clone the destination prop, since we want a unique prop struct per arch.
+ dstClone := reflect.New(reflect.ValueOf(dst).Elem().Type()).Interface()
+
+ // Copy the located property struct into the cloned destination property struct.
+ err := proptools.ExtendMatchingProperties([]interface{}{dstClone}, src.Interface(), nil, proptools.OrderReplace)
+ if err != nil {
+ // This is fine, it just means the src struct doesn't match.
+ continue
+ }
+
+ // Found the prop for the os, you have.
+ osToProp[os] = dstClone
+
+ // Go to the next prop.
+ break
+ }
+ }
+ }
+ return osToProp
+}