Merge changes from topic "revert-1302576-NGVCIVIIJO"

* changes:
  Revert "Detect invalid arch specific properties in snapshot"
  Revert "Adds support for 'ignored-on-host'"
  Revert "Fix snapshot of a host/device cc_library with stubs"
diff --git a/android/sdk.go b/android/sdk.go
index e823106..873e089 100644
--- a/android/sdk.go
+++ b/android/sdk.go
@@ -342,24 +342,9 @@
 	//
 	// * The variant property structs are analysed to find exported (capitalized) fields which
 	//   have common values. Those fields are cleared and the common value added to the common
-	//   properties.
-	//
-	//   A field annotated with a tag of `sdk:"keep"` will be treated as if it
+	//   properties. A field annotated with a tag of `sdk:"keep"` will be treated as if it
 	//   was not capitalized, i.e. not optimized for common values.
 	//
-	//   A field annotated with a tag of `android:"arch_variant"` will be allowed to have
-	//   values that differ by arch, fields not tagged as such must have common values across
-	//   all variants.
-	//
-	// * Additional field tags can be specified on a field that will ignore certain values
-	//   for the purpose of common value optimization. A value that is ignored must have the
-	//   default value for the property type. This is to ensure that significant value are not
-	//   ignored by accident. The purpose of this is to allow the snapshot generation to reflect
-	//   the behavior of the runtime. e.g. if a property is ignored on the host then a property
-	//   that is common for android can be treated as if it was common for android and host as
-	//   the setting for host is ignored anyway.
-	//   * `sdk:"ignored-on-host" - this indicates the property is ignored on the host variant.
-	//
 	// * The sdk module type populates the BpModule structure, creating the arch specific
 	//   structure and calls AddToPropertySet(...) on the properties struct to add the member
 	//   specific properties in the correct place in the structure.
diff --git a/cc/library_sdk_member.go b/cc/library_sdk_member.go
index a7a1de2..2c8e311 100644
--- a/cc/library_sdk_member.go
+++ b/cc/library_sdk_member.go
@@ -307,7 +307,7 @@
 	// The list of possibly common exported include dirs.
 	//
 	// This field is exported as its contents may not be arch specific.
-	ExportedIncludeDirs android.Paths `android:"arch_variant"`
+	ExportedIncludeDirs android.Paths
 
 	// The list of arch specific exported generated include dirs.
 	//
@@ -322,31 +322,27 @@
 	// The list of possibly common exported system include dirs.
 	//
 	// This field is exported as its contents may not be arch specific.
-	ExportedSystemIncludeDirs android.Paths `android:"arch_variant"`
+	ExportedSystemIncludeDirs android.Paths
 
 	// The list of possibly common exported flags.
 	//
 	// This field is exported as its contents may not be arch specific.
-	ExportedFlags []string `android:"arch_variant"`
+	ExportedFlags []string
 
 	// The set of shared libraries
 	//
 	// This field is exported as its contents may not be arch specific.
-	SharedLibs []string `android:"arch_variant"`
+	SharedLibs []string
 
 	// The set of system shared libraries. Note nil and [] are semantically
 	// distinct - see BaseLinkerProperties.System_shared_libs.
 	//
 	// This field is exported as its contents may not be arch specific.
-	SystemSharedLibs []string `android:"arch_variant"`
+	SystemSharedLibs []string
 
 	// The specific stubs version for the lib variant, or empty string if stubs
 	// are not in use.
-	//
-	// Marked 'ignored-on-host' as the StubsVersion() from which this is initialized is
-	// not set on host and the stubs.versions property which this is written to is does
-	// not vary by arch so cannot be android specific.
-	StubsVersion string `sdk:"ignored-on-host"`
+	StubsVersion string
 
 	// outputFile is not exported as it is always arch specific.
 	outputFile android.Path
diff --git a/java/java.go b/java/java.go
index 9d75c74..472d3da 100644
--- a/java/java.go
+++ b/java/java.go
@@ -1906,7 +1906,7 @@
 type librarySdkMemberProperties struct {
 	android.SdkMemberPropertiesBase
 
-	JarToExport     android.Path `android:"arch_variant"`
+	JarToExport     android.Path
 	AidlIncludeDirs android.Paths
 }
 
diff --git a/sdk/cc_sdk_test.go b/sdk/cc_sdk_test.go
index b77447a..733f7ac 100644
--- a/sdk/cc_sdk_test.go
+++ b/sdk/cc_sdk_test.go
@@ -1805,86 +1805,3 @@
 }
 `))
 }
-
-func TestDeviceAndHostSnapshotWithStubsLibrary(t *testing.T) {
-	result := testSdkWithCc(t, `
-		sdk {
-			name: "mysdk",
-			host_supported: true,
-			native_shared_libs: ["stubslib"],
-		}
-
-		cc_library {
-			name: "internaldep",
-			host_supported: true,
-		}
-
-		cc_library {
-			name: "stubslib",
-			host_supported: true,
-			shared_libs: ["internaldep"],
-			stubs: {
-				symbol_file: "some/where/stubslib.map.txt",
-				versions: ["1", "2", "3"],
-			},
-		}
-	`)
-
-	result.CheckSnapshot("mysdk", "",
-		checkAndroidBpContents(`
-// This is auto-generated. DO NOT EDIT.
-
-cc_prebuilt_library_shared {
-    name: "mysdk_stubslib@current",
-    sdk_member_name: "stubslib",
-    host_supported: true,
-    installable: false,
-    stubs: {
-        versions: ["3"],
-    },
-    target: {
-        android_arm64: {
-            srcs: ["android/arm64/lib/stubslib.so"],
-        },
-        android_arm: {
-            srcs: ["android/arm/lib/stubslib.so"],
-        },
-        linux_glibc_x86_64: {
-            srcs: ["linux_glibc/x86_64/lib/stubslib.so"],
-        },
-        linux_glibc_x86: {
-            srcs: ["linux_glibc/x86/lib/stubslib.so"],
-        },
-    },
-}
-
-cc_prebuilt_library_shared {
-    name: "stubslib",
-    prefer: false,
-    host_supported: true,
-    stubs: {
-        versions: ["3"],
-    },
-    target: {
-        android_arm64: {
-            srcs: ["android/arm64/lib/stubslib.so"],
-        },
-        android_arm: {
-            srcs: ["android/arm/lib/stubslib.so"],
-        },
-        linux_glibc_x86_64: {
-            srcs: ["linux_glibc/x86_64/lib/stubslib.so"],
-        },
-        linux_glibc_x86: {
-            srcs: ["linux_glibc/x86/lib/stubslib.so"],
-        },
-    },
-}
-
-sdk_snapshot {
-    name: "mysdk@current",
-    host_supported: true,
-    native_shared_libs: ["mysdk_stubslib@current"],
-}
-`))
-}
diff --git a/sdk/sdk_test.go b/sdk/sdk_test.go
index ae1a492..095f836 100644
--- a/sdk/sdk_test.go
+++ b/sdk/sdk_test.go
@@ -226,8 +226,8 @@
 }
 
 type EmbeddedPropertiesStruct struct {
-	S_Embedded_Common    string `android:"arch_variant"`
-	S_Embedded_Different string `android:"arch_variant"`
+	S_Embedded_Common    string
+	S_Embedded_Different string
 }
 
 type testPropertiesStruct struct {
@@ -235,11 +235,11 @@
 	private     string
 	Public_Kept string `sdk:"keep"`
 	S_Common    string
-	S_Different string `android:"arch_variant"`
+	S_Different string
 	A_Common    []string
-	A_Different []string `android:"arch_variant"`
+	A_Different []string
 	F_Common    *bool
-	F_Different *bool `android:"arch_variant"`
+	F_Different *bool
 	EmbeddedPropertiesStruct
 }
 
@@ -289,12 +289,9 @@
 	}
 
 	extractor := newCommonValueExtractor(common)
+	extractor.extractCommonProperties(common, structs)
 
 	h := TestHelper{t}
-
-	err := extractor.extractCommonProperties(common, structs)
-	h.AssertDeepEquals("unexpected error", nil, err)
-
 	h.AssertDeepEquals("common properties not correct",
 		&testPropertiesStruct{
 			name:        "common",
@@ -349,26 +346,3 @@
 		},
 		structs[1])
 }
-
-func TestCommonValueOptimization_InvalidArchSpecificVariants(t *testing.T) {
-	common := &testPropertiesStruct{name: "common"}
-	structs := []propertiesContainer{
-		&testPropertiesStruct{
-			name:     "struct-0",
-			S_Common: "should-be-but-is-not-common0",
-		},
-		&testPropertiesStruct{
-			name:     "struct-1",
-			S_Common: "should-be-but-is-not-common1",
-		},
-	}
-
-	extractor := newCommonValueExtractor(common)
-
-	h := TestHelper{t}
-
-	err := extractor.extractCommonProperties(common, structs)
-	h.AssertErrorMessageEquals("unexpected error", `field "S_Common" is not tagged as "arch_variant" but has arch specific properties:
-    "struct-0" has value "should-be-but-is-not-common0"
-    "struct-1" has value "should-be-but-is-not-common1"`, err)
-}
diff --git a/sdk/update.go b/sdk/update.go
index d43a42d..03a5c03 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -982,13 +982,6 @@
 	}
 }
 
-func (osInfo *osTypeSpecificInfo) isHostVariant() bool {
-	osClass := osInfo.osType.Class
-	return osClass == android.Host || osClass == android.HostCross
-}
-
-var _ isHostVariant = (*osTypeSpecificInfo)(nil)
-
 func (osInfo *osTypeSpecificInfo) String() string {
 	return fmt.Sprintf("OsType{%s}", osInfo.osType)
 }
@@ -1222,34 +1215,16 @@
 // struct (or one of its embedded structs).
 type fieldAccessorFunc func(structValue reflect.Value) reflect.Value
 
-// Checks the metadata to determine whether the property should be ignored for the
-// purposes of common value extraction or not.
-type extractorMetadataPredicate func(metadata propertiesContainer) bool
-
-// Indicates whether optimizable properties are provided by a host variant or
-// not.
-type isHostVariant interface {
-	isHostVariant() bool
-}
-
 // A property that can be optimized by the commonValueExtractor.
 type extractorProperty struct {
 	// The name of the field for this property.
 	name string
 
-	// Filter that can use metadata associated with the properties being optimized
-	// to determine whether the field should be ignored during common value
-	// optimization.
-	filter extractorMetadataPredicate
-
 	// Retrieves the value on which common value optimization will be performed.
 	getter fieldAccessorFunc
 
 	// The empty value for the field.
 	emptyValue reflect.Value
-
-	// True if the property can support arch variants false otherwise.
-	archVariant bool
 }
 
 func (p extractorProperty) String() string {
@@ -1295,20 +1270,6 @@
 			continue
 		}
 
-		var filter extractorMetadataPredicate
-
-		// Add a filter
-		if proptools.HasTag(field, "sdk", "ignored-on-host") {
-			filter = func(metadata propertiesContainer) bool {
-				if m, ok := metadata.(isHostVariant); ok {
-					if m.isHostVariant() {
-						return false
-					}
-				}
-				return true
-			}
-		}
-
 		// Save a copy of the field index for use in the function.
 		fieldIndex := f
 
@@ -1340,10 +1301,8 @@
 		} else {
 			property := extractorProperty{
 				name,
-				filter,
 				fieldGetter,
 				reflect.Zero(field.Type),
-				proptools.HasTag(field, "android", "arch_variant"),
 			}
 			e.properties = append(e.properties, property)
 		}
@@ -1409,38 +1368,17 @@
 
 	for _, property := range e.properties {
 		fieldGetter := property.getter
-		filter := property.filter
-		if filter == nil {
-			filter = func(metadata propertiesContainer) bool {
-				return true
-			}
-		}
 
 		// Check to see if all the structures have the same value for the field. The commonValue
-		// is nil on entry to the loop and if it is nil on exit then there is no common value or
-		// all the values have been filtered out, otherwise it points to the common value.
+		// is nil on entry to the loop and if it is nil on exit then there is no common value,
+		// otherwise it points to the common value.
 		var commonValue *reflect.Value
 
-		// Assume that all the values will be the same.
-		//
-		// While similar to this is not quite the same as commonValue == nil. If all the values
-		// have been filtered out then this will be false but commonValue == nil will be true.
-		valuesDiffer := false
-
 		for i := 0; i < sliceValue.Len(); i++ {
 			container := sliceValue.Index(i).Interface().(propertiesContainer)
 			itemValue := reflect.ValueOf(container.optimizableProperties())
 			fieldValue := fieldGetter(itemValue)
 
-			if !filter(container) {
-				expectedValue := property.emptyValue.Interface()
-				actualValue := fieldValue.Interface()
-				if !reflect.DeepEqual(expectedValue, actualValue) {
-					return fmt.Errorf("field %q is supposed to be ignored for %q but is set to %#v instead of %#v", property, container, actualValue, expectedValue)
-				}
-				continue
-			}
-
 			if commonValue == nil {
 				// Use the first value as the commonProperties value.
 				commonValue = &fieldValue
@@ -1449,13 +1387,12 @@
 				// no value in common so break out.
 				if !reflect.DeepEqual(fieldValue.Interface(), commonValue.Interface()) {
 					commonValue = nil
-					valuesDiffer = true
 					break
 				}
 			}
 		}
 
-		// If the fields all have common value then store it in the common struct field
+		// If the fields all have a common value then store it in the common struct field
 		// and set the input struct's field to the empty value.
 		if commonValue != nil {
 			emptyValue := property.emptyValue
@@ -1467,21 +1404,6 @@
 				fieldValue.Set(emptyValue)
 			}
 		}
-
-		if valuesDiffer && !property.archVariant {
-			// The values differ but the property does not support arch variants so it
-			// is an error.
-			var details strings.Builder
-			for i := 0; i < sliceValue.Len(); i++ {
-				container := sliceValue.Index(i).Interface().(propertiesContainer)
-				itemValue := reflect.ValueOf(container.optimizableProperties())
-				fieldValue := fieldGetter(itemValue)
-
-				_, _ = fmt.Fprintf(&details, "\n    %q has value %q", container.String(), fieldValue.Interface())
-			}
-
-			return fmt.Errorf("field %q is not tagged as \"arch_variant\" but has arch specific properties:%s", property.String(), details.String())
-		}
 	}
 
 	return nil