Filter product variable property structs

For each module, take the default product variable properties and
create a new type that contains only the properties that exist in
the current module.  This will provide better errors when attemping
to set product variable properties that will never get used for
a module, and fixes errors when a module attempts to use a product
variable that also contains properties that don't apply to the
current module.

Fixes: 79249983
Test: TestProductVariables
Test: m checkbuild
Change-Id: I4dc24f7781b8ce798651cfc8bf3563005a92c13d

android/mutator.go

@@ -15,6 +15,8 @@
 package android
 
 import (
+	"reflect"
+
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
 )
@@ -244,8 +246,23 @@ func (t *topDownMutatorContext) Rename(name string) {
 }
 
 func (t *topDownMutatorContext) CreateModule(factory ModuleFactory, props ...interface{}) Module {
-	inherited := []interface{}{&t.Module().base().commonProperties, &t.Module().base().variableProperties}
+	inherited := []interface{}{&t.Module().base().commonProperties}
 	module := t.bp.CreateModule(ModuleFactoryAdaptor(factory), append(inherited, props...)...).(Module)
+
+	if t.Module().base().variableProperties != nil && module.base().variableProperties != nil {
+		src := t.Module().base().variableProperties
+		dst := []interface{}{
+			module.base().variableProperties,
+			// Put an empty copy of the src properties into dst so that properties in src that are not in dst
+			// don't cause a "failed to find property to extend" error.
+			proptools.CloneEmptyProperties(reflect.ValueOf(src).Elem()).Interface(),
+		}
+		err := proptools.AppendMatchingProperties(dst, src, nil)
+		if err != nil {
+			panic(err)
+		}
+	}
+
 	return module
 }