Disable all host OS variants except those explicitly included.

Necessary to avoid problems with implicitly enabled host OS'es, e.g.
linux_glibc getting enabled when we only supply a linux_bionic linker
in runtime-module-host-exports. That will then cause a non-functional
prebuilt to take precedence over source if the prebuilt is preferred.

We don't do this for device since we so far only support a single
device OS (android).

This introduces the notion that SDK member types can be host OS
dependent or not. That way java members with host prebuilts don't get
restricted to a specific host OS.

Test: m nothing
Test: build/soong/scripts/build-aml-prebuilts.sh runtime-module-host-exports
  Check that the generated Android.bp correctly disables the bionic
  linker prebuilt for linux_glibc.
Test: art/build/apex/runtests.sh
  on master-art with an updated runtime SDK snapshot
Test: art/tools/buildbot-build.sh {--host,--target}
  on master-art with an updated runtime SDK snapshot
Bug: 160349757
Change-Id: Idad7ef138cdbcbd209d390bf6c10ca8365d4619f

android/sdk.go

@@ -327,6 +327,12 @@ type SdkMemberType interface {
 	// SdkAware and be added with an SdkMemberTypeDependencyTag tag.
 	HasTransitiveSdkMembers() bool
 
+	// Return true if prebuilt host artifacts may be specific to the host OS. Only
+	// applicable to modules where HostSupported() is true. If this is true,
+	// snapshots will list each host OS variant explicitly and disable all other
+	// host OS'es.
+	IsHostOsDependent() bool
+
 	// Add dependencies from the SDK module to all the module variants the member
 	// type contributes to the SDK. `names` is the list of module names given in
 	// the member type property (as returned by SdkPropertyName()) in the SDK
@@ -389,6 +395,7 @@ type SdkMemberTypeBase struct {
 	PropertyName         string
 	SupportsSdk          bool
 	TransitiveSdkMembers bool
+	HostOsDependent      bool
 }
 
 func (b *SdkMemberTypeBase) SdkPropertyName() string {
@@ -403,6 +410,10 @@ func (b *SdkMemberTypeBase) HasTransitiveSdkMembers() bool {
 	return b.TransitiveSdkMembers
 }
 
+func (b *SdkMemberTypeBase) IsHostOsDependent() bool {
+	return b.HostOsDependent
+}
+
 // Encapsulates the information about registered SdkMemberTypes.
 type SdkMemberTypesRegistry struct {
 	// The list of types sorted by property name.

cc/binary_sdk_member.go

@@ -29,7 +29,8 @@ func init() {
 
 var ccBinarySdkMemberType = &binarySdkMemberType{
 	SdkMemberTypeBase: android.SdkMemberTypeBase{
-		PropertyName: "native_binaries",
+		PropertyName:    "native_binaries",
+		HostOsDependent: true,
 	},
 }
 

cc/library_headers.go

@@ -25,8 +25,9 @@ func init() {
 
 var headersLibrarySdkMemberType = &librarySdkMemberType{
 	SdkMemberTypeBase: android.SdkMemberTypeBase{
-		PropertyName: "native_header_libs",
+		PropertyName:    "native_header_libs",
-		SupportsSdk:  true,
+		SupportsSdk:     true,
+		HostOsDependent: true,
 	},
 	prebuiltModuleType: "cc_prebuilt_library_headers",
 	noOutputFiles:      true,

cc/library_sdk_member.go

@@ -27,8 +27,9 @@ import (
 
 var sharedLibrarySdkMemberType = &librarySdkMemberType{
 	SdkMemberTypeBase: android.SdkMemberTypeBase{
-		PropertyName: "native_shared_libs",
+		PropertyName:    "native_shared_libs",
-		SupportsSdk:  true,
+		SupportsSdk:     true,
+		HostOsDependent: true,
 	},
 	prebuiltModuleType: "cc_prebuilt_library_shared",
 	linkTypes:          []string{"shared"},
@@ -36,8 +37,9 @@ var sharedLibrarySdkMemberType = &librarySdkMemberType{
 
 var staticLibrarySdkMemberType = &librarySdkMemberType{
 	SdkMemberTypeBase: android.SdkMemberTypeBase{
-		PropertyName: "native_static_libs",
+		PropertyName:    "native_static_libs",
-		SupportsSdk:  true,
+		SupportsSdk:     true,
+		HostOsDependent: true,
 	},
 	prebuiltModuleType: "cc_prebuilt_library_static",
 	linkTypes:          []string{"static"},
@@ -45,8 +47,9 @@ var staticLibrarySdkMemberType = &librarySdkMemberType{
 
 var staticAndSharedLibrarySdkMemberType = &librarySdkMemberType{
 	SdkMemberTypeBase: android.SdkMemberTypeBase{
-		PropertyName: "native_libs",
+		PropertyName:    "native_libs",
-		SupportsSdk:  true,
+		SupportsSdk:     true,
+		HostOsDependent: true,
 	},
 	prebuiltModuleType: "cc_prebuilt_library",
 	linkTypes:          []string{"static", "shared"},

sdk/cc_sdk_test.go

@@ -39,6 +39,20 @@ func testSdkWithCc(t *testing.T, bp string) *testSdkResult {
 
 // Contains tests for SDK members provided by the cc package.
 
+func TestSingleDeviceOsAssumption(t *testing.T) {
+	// Mock a module with DeviceSupported() == true.
+	s := &sdk{}
+	android.InitAndroidArchModule(s, android.DeviceSupported, android.MultilibCommon)
+
+	osTypes := s.getPossibleOsTypes()
+	if len(osTypes) != 1 {
+		// The snapshot generation assumes there is a single device OS. If more are
+		// added it might need to disable them by default, like it does for host
+		// OS'es.
+		t.Errorf("expected a single device OS, got %v", osTypes)
+	}
+}
+
 func TestSdkIsCompileMultilibBoth(t *testing.T) {
 	result := testSdkWithCc(t, `
 		sdk {
@@ -99,9 +113,15 @@ cc_prebuilt_library_shared {
     stl: "none",
     compile_multilib: "64",
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/sdkmember.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/sdkmember.so"],
         },
@@ -115,9 +135,15 @@ cc_prebuilt_library_shared {
     stl: "none",
     compile_multilib: "64",
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/sdkmember.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/sdkmember.so"],
         },
@@ -129,6 +155,14 @@ sdk_snapshot {
     host_supported: true,
     native_shared_libs: ["mysdk_sdkmember@current"],
     compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -573,7 +607,11 @@ cc_prebuilt_binary {
     installable: false,
     stl: "none",
     target: {
+        host: {
+            enabled: false,
+        },
         linux_glibc: {
+            enabled: true,
             compile_multilib: "both",
         },
         linux_glibc_x86_64: {
@@ -583,6 +621,7 @@ cc_prebuilt_binary {
             srcs: ["linux_glibc/x86/bin/mynativebinary"],
         },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
         windows_x86_64: {
@@ -598,7 +637,11 @@ cc_prebuilt_binary {
     host_supported: true,
     stl: "none",
     target: {
+        host: {
+            enabled: false,
+        },
         linux_glibc: {
+            enabled: true,
             compile_multilib: "both",
         },
         linux_glibc_x86_64: {
@@ -608,6 +651,7 @@ cc_prebuilt_binary {
             srcs: ["linux_glibc/x86/bin/mynativebinary"],
         },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
         windows_x86_64: {
@@ -622,7 +666,14 @@ module_exports_snapshot {
     host_supported: true,
     native_binaries: ["myexports_mynativebinary@current"],
     target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
     },
@@ -636,6 +687,162 @@ module_exports_snapshot {
 	)
 }
 
+func TestSnapshotWithSingleHostOsType(t *testing.T) {
+	ctx, config := testSdkContext(`
+		cc_defaults {
+			name: "mydefaults",
+			device_supported: false,
+			host_supported: true,
+			compile_multilib: "64",
+			target: {
+				host: {
+					enabled: false,
+				},
+				linux_bionic: {
+					enabled: true,
+				},
+			},
+		}
+
+		module_exports {
+			name: "myexports",
+			defaults: ["mydefaults"],
+			native_shared_libs: ["mynativelib"],
+			native_binaries: ["mynativebinary"],
+			compile_multilib: "64",  // The built-in default in sdk.go overrides mydefaults.
+		}
+
+		cc_library {
+			name: "mynativelib",
+			defaults: ["mydefaults"],
+			srcs: [
+				"Test.cpp",
+			],
+			stl: "none",
+		}
+
+		cc_binary {
+			name: "mynativebinary",
+			defaults: ["mydefaults"],
+			srcs: [
+				"Test.cpp",
+			],
+			stl: "none",
+		}
+	`, ccTestFs, []android.OsType{android.LinuxBionic})
+
+	result := runTests(t, ctx, config)
+
+	result.CheckSnapshot("myexports", "",
+		checkAndroidBpContents(`
+// This is auto-generated. DO NOT EDIT.
+
+cc_prebuilt_binary {
+    name: "myexports_mynativebinary@current",
+    sdk_member_name: "mynativebinary",
+    device_supported: false,
+    host_supported: true,
+    installable: false,
+    stl: "none",
+    compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+        linux_bionic_x86_64: {
+            srcs: ["x86_64/bin/mynativebinary"],
+        },
+    },
+}
+
+cc_prebuilt_binary {
+    name: "mynativebinary",
+    prefer: false,
+    device_supported: false,
+    host_supported: true,
+    stl: "none",
+    compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+        linux_bionic_x86_64: {
+            srcs: ["x86_64/bin/mynativebinary"],
+        },
+    },
+}
+
+cc_prebuilt_library_shared {
+    name: "myexports_mynativelib@current",
+    sdk_member_name: "mynativelib",
+    device_supported: false,
+    host_supported: true,
+    installable: false,
+    stl: "none",
+    compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+        linux_bionic_x86_64: {
+            srcs: ["x86_64/lib/mynativelib.so"],
+        },
+    },
+}
+
+cc_prebuilt_library_shared {
+    name: "mynativelib",
+    prefer: false,
+    device_supported: false,
+    host_supported: true,
+    stl: "none",
+    compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+        linux_bionic_x86_64: {
+            srcs: ["x86_64/lib/mynativelib.so"],
+        },
+    },
+}
+
+module_exports_snapshot {
+    name: "myexports@current",
+    device_supported: false,
+    host_supported: true,
+    native_binaries: ["myexports_mynativebinary@current"],
+    native_shared_libs: ["myexports_mynativelib@current"],
+    compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_bionic: {
+            enabled: true,
+        },
+    },
+}
+`),
+		checkAllCopyRules(`
+.intermediates/mynativebinary/linux_bionic_x86_64/mynativebinary -> x86_64/bin/mynativebinary
+.intermediates/mynativelib/linux_bionic_x86_64_shared/mynativelib.so -> x86_64/lib/mynativelib.so
+`),
+	)
+}
+
 // Test that we support the necessary flags for the linker binary, which is
 // special in several ways.
 func TestSnapshotWithCcStaticNocrtBinary(t *testing.T) {
@@ -674,11 +881,17 @@ cc_prebuilt_binary {
     compile_multilib: "both",
     static_executable: true,
     nocrt: true,
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/bin/linker"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/bin/linker"],
         },
     },
@@ -693,11 +906,17 @@ cc_prebuilt_binary {
     compile_multilib: "both",
     static_executable: true,
     nocrt: true,
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/bin/linker"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/bin/linker"],
         },
     },
@@ -708,6 +927,14 @@ module_exports_snapshot {
     device_supported: false,
     host_supported: true,
     native_binaries: ["mymodule_exports_linker@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -1034,12 +1261,18 @@ cc_prebuilt_library_shared {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.so"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/lib/mynativelib.so"],
             export_include_dirs: ["x86/include_gen/mynativelib"],
         },
@@ -1055,12 +1288,18 @@ cc_prebuilt_library_shared {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.so"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/lib/mynativelib.so"],
             export_include_dirs: ["x86/include_gen/mynativelib"],
         },
@@ -1072,6 +1311,14 @@ sdk_snapshot {
     device_supported: false,
     host_supported: true,
     native_shared_libs: ["mysdk_mynativelib@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -1130,7 +1377,11 @@ cc_prebuilt_library_shared {
     installable: false,
     stl: "none",
     target: {
+        host: {
+            enabled: false,
+        },
         linux_glibc: {
+            enabled: true,
             compile_multilib: "both",
         },
         linux_glibc_x86_64: {
@@ -1140,6 +1391,7 @@ cc_prebuilt_library_shared {
             srcs: ["linux_glibc/x86/lib/mynativelib.so"],
         },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
         windows_x86_64: {
@@ -1155,7 +1407,11 @@ cc_prebuilt_library_shared {
     host_supported: true,
     stl: "none",
     target: {
+        host: {
+            enabled: false,
+        },
         linux_glibc: {
+            enabled: true,
             compile_multilib: "both",
         },
         linux_glibc_x86_64: {
@@ -1165,6 +1421,7 @@ cc_prebuilt_library_shared {
             srcs: ["linux_glibc/x86/lib/mynativelib.so"],
         },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
         windows_x86_64: {
@@ -1179,7 +1436,14 @@ sdk_snapshot {
     host_supported: true,
     native_shared_libs: ["mysdk_mynativelib@current"],
     target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
         windows: {
+            enabled: true,
             compile_multilib: "64",
         },
     },
@@ -1312,12 +1576,18 @@ cc_prebuilt_library_static {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.a"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/lib/mynativelib.a"],
             export_include_dirs: ["x86/include_gen/mynativelib"],
         },
@@ -1332,12 +1602,18 @@ cc_prebuilt_library_static {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.a"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
-        x86: {
+        linux_glibc_x86: {
             srcs: ["x86/lib/mynativelib.a"],
             export_include_dirs: ["x86/include_gen/mynativelib"],
         },
@@ -1349,6 +1625,14 @@ module_exports_snapshot {
     device_supported: false,
     host_supported: true,
     native_static_libs: ["myexports_mynativelib@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -1496,8 +1780,14 @@ cc_prebuilt_library_static {
     stl: "none",
     compile_multilib: "64",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.a"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
@@ -1512,8 +1802,14 @@ cc_prebuilt_library_static {
     stl: "none",
     compile_multilib: "64",
     export_include_dirs: ["include/include"],
-    arch: {
+    target: {
-        x86_64: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+        linux_glibc_x86_64: {
             srcs: ["x86_64/lib/mynativelib.a"],
             export_include_dirs: ["x86_64/include_gen/mynativelib"],
         },
@@ -1526,6 +1822,14 @@ module_exports_snapshot {
     host_supported: true,
     native_static_libs: ["myexports_mynativelib@current"],
     compile_multilib: "64",
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }`),
 		checkAllCopyRules(`
 include/Test.h -> include/include/Test.h
@@ -1612,6 +1916,14 @@ cc_prebuilt_library_headers {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 
 cc_prebuilt_library_headers {
@@ -1622,6 +1934,14 @@ cc_prebuilt_library_headers {
     stl: "none",
     compile_multilib: "both",
     export_include_dirs: ["include/include"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 
 sdk_snapshot {
@@ -1629,6 +1949,14 @@ sdk_snapshot {
     device_supported: false,
     host_supported: true,
     native_header_libs: ["mysdk_mynativeheaders@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -1673,10 +2001,14 @@ cc_prebuilt_library_headers {
     compile_multilib: "both",
     export_system_include_dirs: ["common_os/include/include"],
     target: {
+        host: {
+            enabled: false,
+        },
         android: {
             export_include_dirs: ["android/include/include-android"],
         },
         linux_glibc: {
+            enabled: true,
             export_include_dirs: ["linux_glibc/include/include-host"],
         },
     },
@@ -1690,10 +2022,14 @@ cc_prebuilt_library_headers {
     compile_multilib: "both",
     export_system_include_dirs: ["common_os/include/include"],
     target: {
+        host: {
+            enabled: false,
+        },
         android: {
             export_include_dirs: ["android/include/include-android"],
         },
         linux_glibc: {
+            enabled: true,
             export_include_dirs: ["linux_glibc/include/include-host"],
         },
     },
@@ -1703,6 +2039,14 @@ sdk_snapshot {
     name: "mysdk@current",
     host_supported: true,
     native_header_libs: ["mysdk_mynativeheaders@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`
@@ -1870,6 +2214,9 @@ cc_prebuilt_library_shared {
     installable: false,
     compile_multilib: "both",
     target: {
+        host: {
+            enabled: false,
+        },
         android: {
             system_shared_libs: [],
         },
@@ -1879,6 +2226,9 @@ cc_prebuilt_library_shared {
         android_arm: {
             srcs: ["android/arm/lib/sslvariants.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/sslvariants.so"],
         },
@@ -1894,6 +2244,9 @@ cc_prebuilt_library_shared {
     host_supported: true,
     compile_multilib: "both",
     target: {
+        host: {
+            enabled: false,
+        },
         android: {
             system_shared_libs: [],
         },
@@ -1903,6 +2256,9 @@ cc_prebuilt_library_shared {
         android_arm: {
             srcs: ["android/arm/lib/sslvariants.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/sslvariants.so"],
         },
@@ -1916,6 +2272,14 @@ sdk_snapshot {
     name: "mysdk@current",
     host_supported: true,
     native_shared_libs: ["mysdk_sslvariants@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `))
 }
@@ -2025,12 +2389,18 @@ cc_prebuilt_library_shared {
         versions: ["3"],
     },
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/stubslib.so"],
         },
         android_arm: {
             srcs: ["android/arm/lib/stubslib.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/stubslib.so"],
         },
@@ -2049,12 +2419,18 @@ cc_prebuilt_library_shared {
         versions: ["3"],
     },
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/stubslib.so"],
         },
         android_arm: {
             srcs: ["android/arm/lib/stubslib.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/stubslib.so"],
         },
@@ -2068,6 +2444,14 @@ sdk_snapshot {
     name: "mysdk@current",
     host_supported: true,
     native_shared_libs: ["mysdk_stubslib@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `))
 }
@@ -2099,12 +2483,18 @@ cc_prebuilt_library_shared {
     unique_host_soname: true,
     compile_multilib: "both",
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/mylib.so"],
         },
         android_arm: {
             srcs: ["android/arm/lib/mylib.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/mylib-host.so"],
         },
@@ -2121,12 +2511,18 @@ cc_prebuilt_library_shared {
     unique_host_soname: true,
     compile_multilib: "both",
     target: {
+        host: {
+            enabled: false,
+        },
         android_arm64: {
             srcs: ["android/arm64/lib/mylib.so"],
         },
         android_arm: {
             srcs: ["android/arm/lib/mylib.so"],
         },
+        linux_glibc: {
+            enabled: true,
+        },
         linux_glibc_x86_64: {
             srcs: ["linux_glibc/x86_64/lib/mylib-host.so"],
         },
@@ -2140,6 +2536,14 @@ sdk_snapshot {
     name: "mysdk@current",
     host_supported: true,
     native_shared_libs: ["mysdk_mylib@current"],
+    target: {
+        host: {
+            enabled: false,
+        },
+        linux_glibc: {
+            enabled: true,
+        },
+    },
 }
 `),
 		checkAllCopyRules(`

sdk/update.go

@@ -262,7 +262,7 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 		memberCtx := &memberContext{ctx, builder, memberType, member.name}
 
 		prebuiltModule := memberType.AddPrebuiltModule(memberCtx, member)
-		s.createMemberSnapshot(memberCtx, member, prebuiltModule)
+		s.createMemberSnapshot(memberCtx, member, prebuiltModule.(*bpModule))
 	}
 
 	// Create a transformer that will transform an unversioned module into a versioned module.
@@ -345,12 +345,37 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 		snapshotModule.AddProperty("compile_multilib", commonVariantProperties.Compile_multilib)
 	}
 
-	// Iterate over the os types in a fixed order.
 	targetPropertySet := snapshotModule.AddPropertySet("target")
+
+	// If host is supported and any member is host OS dependent then disable host
+	// by default, so that we can enable each host OS variant explicitly. This
+	// avoids problems with implicitly enabled OS variants when the snapshot is
+	// used, which might be different from this run (e.g. different build OS).
+	hasHostOsDependentMember := false
+	if s.HostSupported() {
+		for _, memberRef := range memberRefs {
+			if memberRef.memberType.IsHostOsDependent() {
+				hasHostOsDependentMember = true
+				break
+			}
+		}
+		if hasHostOsDependentMember {
+			hostPropertySet := targetPropertySet.AddPropertySet("host")
+			hostPropertySet.AddProperty("enabled", false)
+		}
+	}
+
+	// Iterate over the os types in a fixed order.
 	for _, osType := range s.getPossibleOsTypes() {
 		if sdkVariant, ok := osTypeToMemberProperties[osType]; ok {
 			osPropertySet := targetPropertySet.AddPropertySet(sdkVariant.Target().Os.Name)
 
+			// Enable the variant explicitly when we've disabled it by default on host.
+			if hasHostOsDependentMember &&
+				(osType.Class == android.Host || osType.Class == android.HostCross) {
+				osPropertySet.AddProperty("enabled", true)
+			}
+
 			variantProps := variantToProperties[sdkVariant]
 			if variantProps.Compile_multilib != "" && variantProps.Compile_multilib != "both" {
 				osPropertySet.AddProperty("compile_multilib", variantProps.Compile_multilib)
@@ -993,9 +1018,12 @@ func (osInfo *osTypeSpecificInfo) addToPropertySet(ctx *memberContext, bpModule
 	var osPropertySet android.BpPropertySet
 	var archPropertySet android.BpPropertySet
 	var archOsPrefix string
-	if osInfo.Properties.Base().Os_count == 1 {
+	if osInfo.Properties.Base().Os_count == 1 &&
-		// There is only one os type present in the variants so don't bother
+		(osInfo.osType.Class == android.Device || !ctx.memberType.IsHostOsDependent()) {
-		// with adding target specific properties.
+		// There is only one OS type present in the variants and it shouldn't have a
+		// variant-specific target. The latter is the case if it's either for device
+		// where there is only one OS (android), or for host and the member type
+		// isn't host OS dependent.
 
 		// Create a structure that looks like:
 		// module_type {
@@ -1032,6 +1060,12 @@ func (osInfo *osTypeSpecificInfo) addToPropertySet(ctx *memberContext, bpModule
 		osPropertySet = targetPropertySet.AddPropertySet(osType.Name)
 		archPropertySet = targetPropertySet
 
+		// Enable the variant explicitly when we've disabled it by default on host.
+		if ctx.memberType.IsHostOsDependent() &&
+			(osType.Class == android.Host || osType.Class == android.HostCross) {
+			osPropertySet.AddProperty("enabled", true)
+		}
+
 		// Arch specific properties need to be added to an os and arch specific
 		// section prefixed with <os>_.
 		archOsPrefix = osType.Name + "_"
@@ -1202,7 +1236,7 @@ func (m *memberContext) Name() string {
 	return m.name
 }
 
-func (s *sdk) createMemberSnapshot(ctx *memberContext, member *sdkMember, bpModule android.BpModule) {
+func (s *sdk) createMemberSnapshot(ctx *memberContext, member *sdkMember, bpModule *bpModule) {
 
 	memberType := member.memberType
 
@@ -1256,6 +1290,18 @@ func (s *sdk) createMemberSnapshot(ctx *memberContext, member *sdkMember, bpModu
 	// added.
 	targetPropertySet := bpModule.AddPropertySet("target")
 
+	// If the member is host OS dependent and has host_supported then disable by
+	// default and enable each host OS variant explicitly. This avoids problems
+	// with implicitly enabled OS variants when the snapshot is used, which might
+	// be different from this run (e.g. different build OS).
+	if ctx.memberType.IsHostOsDependent() {
+		hostSupported := bpModule.getValue("host_supported") == true // Missing means false.
+		if hostSupported {
+			hostPropertySet := targetPropertySet.AddPropertySet("host")
+			hostPropertySet.AddProperty("enabled", false)
+		}
+	}
+
 	// Iterate over the os types in a fixed order.
 	for _, osType := range s.getPossibleOsTypes() {
 		osInfo := osTypeToInfo[osType]