Allow pruning of unsupported fields in structs in maps

Adds support for traversing into a field that is of type:
   map[...]*struct{...}

This is needed to allow java_sdk_library to mark scope specific
properties, e.g. public.annotations as being target build release
specific.

It was necessary to change the Scope field from:
   Scope map[*apiScope]scopeProperties
to:
   Scope map[*apiScope]*scopeProperties

That is because there is no way in go to change the field of a struct
value of a map. i.e. you cannot do the following, not even using
reflection:
   Scope[apiScopePublic].AnnotationsZip = nil

Bug: 204763318
Test: m nothing
Change-Id: Id103f70f55d4202971321ef4925cbec4b55f8136

3 files changed, 77 insertions, 3 deletions

diff --git a/java/sdk_library.go b/java/sdk_library.go
index 57ab2686f..98f29990d 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -2755,7 +2755,7 @@ type sdkLibrarySdkMemberProperties struct {
 	android.SdkMemberPropertiesBase
 
 	// Scope to per scope properties.
-	Scopes map[*apiScope]scopeProperties
+	Scopes map[*apiScope]*scopeProperties
 
 	// The Java stubs source files.
 	Stub_srcs []string
@@ -2815,7 +2815,7 @@ type scopeProperties struct {
 func (s *sdkLibrarySdkMemberProperties) PopulateFromVariant(ctx android.SdkMemberContext, variant android.Module) {
 	sdk := variant.(*SdkLibrary)
 
-	s.Scopes = make(map[*apiScope]scopeProperties)
+	s.Scopes = make(map[*apiScope]*scopeProperties)
 	for _, apiScope := range allApiScopes {
 		paths := sdk.findScopePaths(apiScope)
 		if paths == nil {
@@ -2838,7 +2838,7 @@ func (s *sdkLibrarySdkMemberProperties) PopulateFromVariant(ctx android.SdkMembe
 			if paths.annotationsZip.Valid() {
 				properties.AnnotationsZip = paths.annotationsZip.Path()
 			}
-			s.Scopes[apiScope] = properties
+			s.Scopes[apiScope] = &properties
 		}
 	}
 
diff --git a/sdk/build_release.go b/sdk/build_release.go
index 212582ac6..2bcdc6f57 100644
--- a/sdk/build_release.go
+++ b/sdk/build_release.go
@@ -269,6 +269,51 @@ func (p *propertyPruner) gatherFields(structType reflect.Type, containingStructA
 					subNamePrefix = name + "."
 				}
 				p.gatherFields(fieldType, fieldGetter, subNamePrefix, selector)
+
+			case reflect.Map:
+				// Get the type of the values stored in the map.
+				valueType := fieldType.Elem()
+				// Skip over * types.
+				if valueType.Kind() == reflect.Ptr {
+					valueType = valueType.Elem()
+				}
+				if valueType.Kind() == reflect.Struct {
+					// If this is not referenced by a pointer then it is an error as it is impossible to
+					// modify a struct that is stored directly as a value in a map.
+					if fieldType.Elem().Kind() != reflect.Ptr {
+						panic(fmt.Errorf("Cannot prune struct %s stored by value in map %s, map values must"+
+							" be pointers to structs",
+							fieldType.Elem(), name))
+					}
+
+					// Create a new pruner for the values of the map.
+					valuePruner := newPropertyPrunerForStructType(valueType, selector)
+
+					// Create a new fieldPruner that will iterate over all the items in the map and call the
+					// pruner on them.
+					fieldPruner := func(container reflect.Value) {
+						mapValue := fieldGetter(container)
+
+						for _, keyValue := range mapValue.MapKeys() {
+							itemValue := mapValue.MapIndex(keyValue)
+
+							defer func() {
+								if r := recover(); r != nil {
+									panic(fmt.Errorf("%s\n\tfor key %q", r, keyValue))
+								}
+							}()
+
+							valuePruner.pruneProperties(itemValue.Interface())
+						}
+					}
+
+					// Add the map field pruner to the list of property pruners.
+					property := prunerProperty{
+						name + "[*]",
+						fieldPruner,
+					}
+					p.properties = append(p.properties, property)
+				}
 			}
 		}
 	}
@@ -304,6 +349,13 @@ type fieldSelectorFunc func(name string, field reflect.StructField) bool
 // of properties.
 func newPropertyPruner(propertiesStruct interface{}, selector fieldSelectorFunc) *propertyPruner {
 	structType := getStructValue(reflect.ValueOf(propertiesStruct)).Type()
+	return newPropertyPrunerForStructType(structType, selector)
+}
+
+// newPropertyPruner creates a new property pruner for the supplied properties struct type.
+//
+// The returned pruner can be used on any properties structure of the supplied type.
+func newPropertyPrunerForStructType(structType reflect.Type, selector fieldSelectorFunc) *propertyPruner {
 	pruner := &propertyPruner{}
 	pruner.gatherFields(structType, nil, "", selector)
 	return pruner
diff --git a/sdk/build_release_test.go b/sdk/build_release_test.go
index 0ec10409f..6608be4f8 100644
--- a/sdk/build_release_test.go
+++ b/sdk/build_release_test.go
@@ -126,11 +126,17 @@ func TestPropertyPrunerByBuildRelease(t *testing.T) {
 		F1_only string `supported_build_releases:"F1"`
 	}
 
+	type mapped struct {
+		Default string
+		T_only  string `supported_build_releases:"T"`
+	}
+
 	type testBuildReleasePruner struct {
 		Default      string
 		S_and_T_only string `supported_build_releases:"S-T"`
 		T_later      string `supported_build_releases:"T+"`
 		Nested       nested
+		Mapped       map[string]*mapped
 	}
 
 	inputFactory := func() testBuildReleasePruner {
@@ -141,6 +147,16 @@ func TestPropertyPrunerByBuildRelease(t *testing.T) {
 			Nested: nested{
 				F1_only: "F1_only",
 			},
+			Mapped: map[string]*mapped{
+				"one": {
+					Default: "one-default",
+					T_only:  "one-t-only",
+				},
+				"two": {
+					Default: "two-default",
+					T_only:  "two-t-only",
+				},
+			},
 		}
 	}
 
@@ -169,6 +185,8 @@ func TestPropertyPrunerByBuildRelease(t *testing.T) {
 		expected := inputFactory()
 		expected.T_later = ""
 		expected.Nested.F1_only = ""
+		expected.Mapped["one"].T_only = ""
+		expected.Mapped["two"].T_only = ""
 		assertJsonEquals(t, expected, testStruct)
 	})
 
@@ -189,6 +207,8 @@ func TestPropertyPrunerByBuildRelease(t *testing.T) {
 
 		expected := inputFactory()
 		expected.S_and_T_only = ""
+		expected.Mapped["one"].T_only = ""
+		expected.Mapped["two"].T_only = ""
 		assertJsonEquals(t, expected, testStruct)
 	})
 
@@ -200,6 +220,8 @@ func TestPropertyPrunerByBuildRelease(t *testing.T) {
 		expected := inputFactory()
 		expected.S_and_T_only = ""
 		expected.Nested.F1_only = ""
+		expected.Mapped["one"].T_only = ""
+		expected.Mapped["two"].T_only = ""
 		assertJsonEquals(t, expected, testStruct)
 	})
 }