Handle arch-variant in prebuilt_etc

For cc_binary, changing the handling of version_script to no longer be a
LabelAttribute, which reduces test coverage of that type. Expand
prebuilt_etc to handle arch-variant srcs and correct a bug in
LabelAttribute.

Test: build/bazel/ci/bp2build.sh
Change-Id: I620bc3a43b28c1873f335e30099844ca79ce94c1
diff --git a/bp2build/configurability.go b/bp2build/configurability.go
index 005f13d..0bcf91d 100644
--- a/bp2build/configurability.go
+++ b/bp2build/configurability.go
@@ -48,6 +48,12 @@
 		}
 	}
 
+	// if there is a select, use the base value as the conditions default value
+	if len(ret) > 0 {
+		ret[bazel.ConditionsDefaultSelectKey] = value
+		value = reflect.Zero(value.Type())
+	}
+
 	return value, []selects{ret}
 }
 
diff --git a/bp2build/prebuilt_etc_conversion_test.go b/bp2build/prebuilt_etc_conversion_test.go
index 4e25d1b..62e407b 100644
--- a/bp2build/prebuilt_etc_conversion_test.go
+++ b/bp2build/prebuilt_etc_conversion_test.go
@@ -53,3 +53,40 @@
     sub_dir = "tz",
 )`}})
 }
+
+func TestPrebuiltEtcArchVariant(t *testing.T) {
+	runPrebuiltEtcTestCase(t, bp2buildTestCase{
+		description:                        "prebuilt_etc - simple example",
+		moduleTypeUnderTest:                "prebuilt_etc",
+		moduleTypeUnderTestFactory:         etc.PrebuiltEtcFactory,
+		moduleTypeUnderTestBp2BuildMutator: etc.PrebuiltEtcBp2Build,
+		filesystem:                         map[string]string{},
+		blueprint: `
+prebuilt_etc {
+    name: "apex_tz_version",
+    src: "version/tz_version",
+    filename: "tz_version",
+    sub_dir: "tz",
+    installable: false,
+    arch: {
+      arm: {
+        src: "arm",
+      },
+      arm64: {
+        src: "arm64",
+      },
+    }
+}
+`,
+		expectedBazelTargets: []string{`prebuilt_etc(
+    name = "apex_tz_version",
+    filename = "tz_version",
+    installable = False,
+    src = select({
+        "//build/bazel/platforms/arch:arm": "arm",
+        "//build/bazel/platforms/arch:arm64": "arm64",
+        "//conditions:default": "version/tz_version",
+    }),
+    sub_dir = "tz",
+)`}})
+}
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index 85abf59..408eb51 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -673,8 +673,16 @@
 
 func prebuiltEtcBp2BuildInternal(ctx android.TopDownMutatorContext, module *PrebuiltEtc) {
 	var srcLabelAttribute bazel.LabelAttribute
-	if module.properties.Src != nil {
-		srcLabelAttribute.SetValue(android.BazelLabelForModuleSrcSingle(ctx, *module.properties.Src))
+	for axis, configToProps := range module.GetArchVariantProperties(ctx, &prebuiltEtcProperties{}) {
+		for config, p := range configToProps {
+			props, ok := p.(*prebuiltEtcProperties)
+			if !ok {
+				continue
+			}
+			if props.Src != nil {
+				srcLabelAttribute.SetSelectValue(axis, config, android.BazelLabelForModuleSrcSingle(ctx, *props.Src))
+			}
+		}
 	}
 
 	var filename string