Add sdk:"keep" tag support

Fields tagged with `sdk:"keep"` will keep the value even if it would
normally be cleared because it was common across a number of structs.
This will allow a module type to specify the same value across all
structs populated directly from variants and have it be copied into all
common property structs without clearing it from the variant specific
structs.

Bug: 248258460
Test: m nothing
Change-Id: I147d946b11fd8766a7d875d9206e8f5034f585d6

1 files changed, 15 insertions, 5 deletions

diff --git a/sdk/update.go b/sdk/update.go
index f20f1d6e9..92a13fa7f 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -2172,6 +2172,11 @@ type extractorProperty struct {
 	// Retrieves the value on which common value optimization will be performed.
 	getter fieldAccessorFunc
 
+	// True if the field should never be cleared.
+	//
+	// This is set to true if and only if the field is annotated with `sdk:"keep"`.
+	keep bool
+
 	// The empty value for the field.
 	emptyValue reflect.Value
 
@@ -2236,6 +2241,8 @@ func (e *commonValueExtractor) gatherFields(structType reflect.Type, containingS
 			}
 		}
 
+		keep := proptools.HasTag(field, "sdk", "keep")
+
 		// Save a copy of the field index for use in the function.
 		fieldIndex := f
 
@@ -2275,6 +2282,7 @@ func (e *commonValueExtractor) gatherFields(structType reflect.Type, containingS
 				name,
 				filter,
 				fieldGetter,
+				keep,
 				reflect.Zero(field.Type),
 				proptools.HasTag(field, "android", "arch_variant"),
 			}
@@ -2394,11 +2402,13 @@ func (e *commonValueExtractor) extractCommonProperties(commonProperties interfac
 		if commonValue != nil {
 			emptyValue := property.emptyValue
 			fieldGetter(commonStructValue).Set(*commonValue)
-			for i := 0; i < sliceValue.Len(); i++ {
-				container := sliceValue.Index(i).Interface().(propertiesContainer)
-				itemValue := reflect.ValueOf(container.optimizableProperties())
-				fieldValue := fieldGetter(itemValue)
-				fieldValue.Set(emptyValue)
+			if !property.keep {
+				for i := 0; i < sliceValue.Len(); i++ {
+					container := sliceValue.Index(i).Interface().(propertiesContainer)
+					itemValue := reflect.ValueOf(container.optimizableProperties())
+					fieldValue := fieldGetter(itemValue)
+					fieldValue.Set(emptyValue)
+				}
 			}
 		}