Allow extractCommonProperties to return an error

Refactoring in preparation for follow up changes.

Also:
* Adds a new AssertErrorMessageEquals() helper method.
* Improved error reporting in the accessor and added name to
  extractorProperty to ensure meaningful errors are reported.
* Added String() string method to propertiesContainer.
* Reports errors using the field name as the errors are not really
  fixable by developers and it is more meaningful to the build team.

Bug: 155628860
Test: m nothing
Change-Id: I5c5b8436bcbc39e4e7cd35df2577b2dac53e702a

sdk/update.go

@@ -306,13 +306,13 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 	for _, sdkVariant := range sdkVariants {
 		properties := sdkVariant.dynamicMemberTypeListProperties
 		osTypeToMemberProperties[sdkVariant.Target().Os] = sdkVariant
-		dynamicMemberPropertiesContainers = append(dynamicMemberPropertiesContainers, &dynamicMemberPropertiesContainer{properties})
+		dynamicMemberPropertiesContainers = append(dynamicMemberPropertiesContainers, &dynamicMemberPropertiesContainer{sdkVariant, properties})
 	}
 
 	// Extract the common lists of members into a separate struct.
 	commonDynamicMemberProperties := s.dynamicSdkMemberTypes.createMemberListProperties()
 	extractor := newCommonValueExtractor(commonDynamicMemberProperties)
-	extractor.extractCommonProperties(commonDynamicMemberProperties, dynamicMemberPropertiesContainers)
+	extractCommonProperties(ctx, extractor, commonDynamicMemberProperties, dynamicMemberPropertiesContainers)
 
 	// Add properties common to all os types.
 	s.addMemberPropertiesToPropertySet(builder, snapshotModule, commonDynamicMemberProperties)
@@ -389,6 +389,13 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 	return outputZipFile
 }
 
+func extractCommonProperties(ctx android.ModuleContext, extractor *commonValueExtractor, commonProperties interface{}, inputPropertiesSlice interface{}) {
+	err := extractor.extractCommonProperties(commonProperties, inputPropertiesSlice)
+	if err != nil {
+		ctx.ModuleErrorf("error extracting common properties: %s", err)
+	}
+}
+
 func (s *sdk) addMemberPropertiesToPropertySet(builder *snapshotBuilder, propertySet android.BpPropertySet, dynamicMemberTypeListProperties interface{}) {
 	for _, memberListProperty := range s.memberListProperties() {
 		names := memberListProperty.getter(dynamicMemberTypeListProperties)
@@ -829,6 +836,8 @@ type osTypeSpecificInfo struct {
 	archInfos []*archTypeSpecificInfo
 }
 
+var _ propertiesContainer = (*osTypeSpecificInfo)(nil)
+
 type variantPropertiesFactoryFunc func() android.SdkMemberProperties
 
 // Create a new osTypeSpecificInfo for the specified os type and its properties
@@ -886,7 +895,7 @@ func newOsTypeSpecificInfo(ctx android.SdkMemberContext, osType android.OsType,
 
 // Optimize the properties by extracting common properties from arch type specific
 // properties into os type specific properties.
-func (osInfo *osTypeSpecificInfo) optimizeProperties(commonValueExtractor *commonValueExtractor) {
+func (osInfo *osTypeSpecificInfo) optimizeProperties(ctx *memberContext, commonValueExtractor *commonValueExtractor) {
 	// Nothing to do if there is only a single common architecture.
 	if len(osInfo.archInfos) == 0 {
 		return
@@ -897,10 +906,10 @@ func (osInfo *osTypeSpecificInfo) optimizeProperties(commonValueExtractor *commo
 		multilib = multilib.addArchType(archInfo.archType)
 
 		// Optimize the arch properties first.
-		archInfo.optimizeProperties(commonValueExtractor)
+		archInfo.optimizeProperties(ctx, commonValueExtractor)
 	}
 
-	commonValueExtractor.extractCommonProperties(osInfo.Properties, osInfo.archInfos)
+	extractCommonProperties(ctx.sdkMemberContext, commonValueExtractor, osInfo.Properties, osInfo.archInfos)
 
 	// Choose setting for compile_multilib that is appropriate for the arch variants supplied.
 	osInfo.Properties.Base().Compile_multilib = multilib.String()
@@ -973,6 +982,10 @@ func (osInfo *osTypeSpecificInfo) addToPropertySet(ctx *memberContext, bpModule
 	}
 }
 
+func (osInfo *osTypeSpecificInfo) String() string {
+	return fmt.Sprintf("OsType{%s}", osInfo.osType)
+}
+
 type archTypeSpecificInfo struct {
 	baseInfo
 
@@ -981,6 +994,8 @@ type archTypeSpecificInfo struct {
 	linkInfos []*linkTypeSpecificInfo
 }
 
+var _ propertiesContainer = (*archTypeSpecificInfo)(nil)
+
 // Create a new archTypeSpecificInfo for the specified arch type and its properties
 // structures populated with information from the variants.
 func newArchSpecificInfo(ctx android.SdkMemberContext, archType android.ArchType, variantPropertiesFactory variantPropertiesFactoryFunc, archVariants []android.Module) *archTypeSpecificInfo {
@@ -1038,12 +1053,12 @@ func getLinkType(variant android.Module) string {
 
 // Optimize the properties by extracting common properties from link type specific
 // properties into arch type specific properties.
-func (archInfo *archTypeSpecificInfo) optimizeProperties(commonValueExtractor *commonValueExtractor) {
+func (archInfo *archTypeSpecificInfo) optimizeProperties(ctx *memberContext, commonValueExtractor *commonValueExtractor) {
 	if len(archInfo.linkInfos) == 0 {
 		return
 	}
 
-	commonValueExtractor.extractCommonProperties(archInfo.Properties, archInfo.linkInfos)
+	extractCommonProperties(ctx.sdkMemberContext, commonValueExtractor, archInfo.Properties, archInfo.linkInfos)
 }
 
 // Add the properties for an arch type to a property set.
@@ -1058,12 +1073,18 @@ func (archInfo *archTypeSpecificInfo) addToPropertySet(ctx *memberContext, archP
 	}
 }
 
+func (archInfo *archTypeSpecificInfo) String() string {
+	return fmt.Sprintf("ArchType{%s}", archInfo.archType)
+}
+
 type linkTypeSpecificInfo struct {
 	baseInfo
 
 	linkType string
 }
 
+var _ propertiesContainer = (*linkTypeSpecificInfo)(nil)
+
 // Create a new linkTypeSpecificInfo for the specified link type and its properties
 // structures populated with information from the variant.
 func newLinkSpecificInfo(ctx android.SdkMemberContext, linkType string, variantPropertiesFactory variantPropertiesFactoryFunc, linkVariant android.Module) *linkTypeSpecificInfo {
@@ -1079,6 +1100,10 @@ func newLinkSpecificInfo(ctx android.SdkMemberContext, linkType string, variantP
 	return linkInfo
 }
 
+func (l *linkTypeSpecificInfo) String() string {
+	return fmt.Sprintf("LinkType{%s}", l.linkType)
+}
+
 type memberContext struct {
 	sdkMemberContext android.ModuleContext
 	builder          *snapshotBuilder
@@ -1143,11 +1168,11 @@ func (s *sdk) createMemberSnapshot(ctx *memberContext, member *sdkMember, bpModu
 		osSpecificPropertiesContainers = append(osSpecificPropertiesContainers, osInfo)
 
 		// Optimize the properties across all the variants for a specific os type.
-		osInfo.optimizeProperties(commonValueExtractor)
+		osInfo.optimizeProperties(ctx, commonValueExtractor)
 	}
 
 	// Extract properties which are common across all architectures and os types.
-	commonValueExtractor.extractCommonProperties(commonProperties, osSpecificPropertiesContainers)
+	extractCommonProperties(ctx.sdkMemberContext, commonValueExtractor, commonProperties, osSpecificPropertiesContainers)
 
 	// Add the common properties to the module.
 	commonProperties.AddToPropertySet(ctx, bpModule)
@@ -1192,6 +1217,9 @@ type fieldAccessorFunc func(structValue reflect.Value) reflect.Value
 
 // A property that can be optimized by the commonValueExtractor.
 type extractorProperty struct {
+	// The name of the field for this property.
+	name string
+
 	// Retrieves the value on which common value optimization will be performed.
 	getter fieldAccessorFunc
 
@@ -1199,6 +1227,10 @@ type extractorProperty struct {
 	emptyValue reflect.Value
 }
 
+func (p extractorProperty) String() string {
+	return p.name
+}
+
 // Supports extracting common values from a number of instances of a properties
 // structure into a separate common set of properties.
 type commonValueExtractor struct {
@@ -1240,6 +1272,9 @@ func (e *commonValueExtractor) gatherFields(structType reflect.Type, containingS
 
 		// Save a copy of the field index for use in the function.
 		fieldIndex := f
+
+		name := field.Name
+
 		fieldGetter := func(value reflect.Value) reflect.Value {
 			if containingStructAccessor != nil {
 				// This is an embedded structure so first access the field for the embedded
@@ -1250,6 +1285,12 @@ func (e *commonValueExtractor) gatherFields(structType reflect.Type, containingS
 			// Skip through interface and pointer values to find the structure.
 			value = getStructValue(value)
 
+			defer func() {
+				if r := recover(); r != nil {
+					panic(fmt.Errorf("%s for fieldIndex %d of field %s of value %#v", r, fieldIndex, name, value.Interface()))
+				}
+			}()
+
 			// Return the field.
 			return value.Field(fieldIndex)
 		}
@@ -1259,6 +1300,7 @@ func (e *commonValueExtractor) gatherFields(structType reflect.Type, containingS
 			e.gatherFields(field.Type, fieldGetter)
 		} else {
 			property := extractorProperty{
+				name,
 				fieldGetter,
 				reflect.Zero(field.Type),
 			}
@@ -1288,12 +1330,15 @@ foundStruct:
 // Allows additional information to be associated with the properties, e.g. for
 // filtering.
 type propertiesContainer interface {
+	fmt.Stringer
+
 	// Get the properties that need optimizing.
 	optimizableProperties() interface{}
 }
 
 // A wrapper for dynamic member properties to allow them to be optimized.
 type dynamicMemberPropertiesContainer struct {
+	sdkVariant              *sdk
 	dynamicMemberProperties interface{}
 }
 
@@ -1301,6 +1346,10 @@ func (c dynamicMemberPropertiesContainer) optimizableProperties() interface{} {
 	return c.dynamicMemberProperties
 }
 
+func (c dynamicMemberPropertiesContainer) String() string {
+	return c.sdkVariant.String()
+}
+
 // Extract common properties from a slice of property structures of the same type.
 //
 // All the property structures must be of the same type.
@@ -1311,7 +1360,7 @@ func (c dynamicMemberPropertiesContainer) optimizableProperties() interface{} {
 // have the same value (using DeepEquals) across all the input properties. If it does not then no
 // change is made. Otherwise, the common value is stored in the field in the commonProperties
 // and the field in each of the input properties structure is set to its default value.
-func (e *commonValueExtractor) extractCommonProperties(commonProperties interface{}, inputPropertiesSlice interface{}) {
+func (e *commonValueExtractor) extractCommonProperties(commonProperties interface{}, inputPropertiesSlice interface{}) error {
 	commonPropertiesValue := reflect.ValueOf(commonProperties)
 	commonStructValue := commonPropertiesValue.Elem()
 
@@ -1356,4 +1405,6 @@ func (e *commonValueExtractor) extractCommonProperties(commonProperties interfac
 			}
 		}
 	}
+
+	return nil
 }