Refine systemfeature codegen behavior

Tweak the semantics of codegen tool feature version args, such that a
`--feature=$FEATURE:$VERSION` arg has the following $VERSION semantics:
  * ""            == undefined (runtime API)
  * valid int     == enabled   (compile-time API)
  * "UNAVAILABLE" == disabled  (compile-time API)

This will simplify how feature args get collected from build flags, and
also aligns with terminology used elsewhere for explicitly disabling
features via the "<unavailable-feature />" tag.

Bug: 203143243
Test: atest systemfeatures-gen-tests systemfeatures-gen-golden-tests
Flag: EXEMPT refactor
Change-Id: I502d455effbe4b81794a5f529406b8b68ac2b372
diff --git a/tools/systemfeatures/tests/golden/RoFeatures.java.gen b/tools/systemfeatures/tests/golden/RoFeatures.java.gen
index 724639b..dfc2937 100644
--- a/tools/systemfeatures/tests/golden/RoFeatures.java.gen
+++ b/tools/systemfeatures/tests/golden/RoFeatures.java.gen
@@ -3,7 +3,7 @@
 //            --readonly=true \
 //            --feature=WATCH:1 \
 //            --feature=WIFI:0 \
-//            --feature=VULKAN:-1 \
+//            --feature=VULKAN:UNAVAILABLE \
 //            --feature=AUTO: \
 //            --feature-apis=WATCH,PC
 package com.android.systemfeatures;
@@ -62,9 +62,8 @@
      *
      * @hide
      */
-    @AssumeFalseForR8
     public static boolean hasFeatureAuto(Context context) {
-        return false;
+        return hasFeatureFallback(context, PackageManager.FEATURE_AUTO);
     }
 
     private static boolean hasFeatureFallback(Context context, String featureName) {
@@ -79,8 +78,7 @@
         switch (featureName) {
             case PackageManager.FEATURE_WATCH: return 1 >= version;
             case PackageManager.FEATURE_WIFI: return 0 >= version;
-            case PackageManager.FEATURE_VULKAN: return -1 >= version;
-            case PackageManager.FEATURE_AUTO: return false;
+            case PackageManager.FEATURE_VULKAN: return false;
             default: break;
         }
         return null;
diff --git a/tools/systemfeatures/tests/golden/RwFeatures.java.gen b/tools/systemfeatures/tests/golden/RwFeatures.java.gen
index 6f89759..89097fb 100644
--- a/tools/systemfeatures/tests/golden/RwFeatures.java.gen
+++ b/tools/systemfeatures/tests/golden/RwFeatures.java.gen
@@ -3,7 +3,7 @@
 //            --readonly=false \
 //            --feature=WATCH:1 \
 //            --feature=WIFI:0 \
-//            --feature=VULKAN:-1 \
+//            --feature=VULKAN:UNAVAILABLE \
 //            --feature=AUTO:
 package com.android.systemfeatures;
 
diff --git a/tools/systemfeatures/tests/src/SystemFeaturesGeneratorTest.java b/tools/systemfeatures/tests/src/SystemFeaturesGeneratorTest.java
index 6dfd244..c3a23cb 100644
--- a/tools/systemfeatures/tests/src/SystemFeaturesGeneratorTest.java
+++ b/tools/systemfeatures/tests/src/SystemFeaturesGeneratorTest.java
@@ -110,10 +110,13 @@
         assertThat(RoFeatures.hasFeatureWatch(mContext)).isTrue();
         assertThat(RoFeatures.hasFeatureWifi(mContext)).isTrue();
         assertThat(RoFeatures.hasFeatureVulkan(mContext)).isFalse();
-        assertThat(RoFeatures.hasFeatureAuto(mContext)).isFalse();
         verify(mPackageManager, never()).hasSystemFeature(anyString(), anyInt());
 
-        // For defined feature types, conditional queries should reflect the build-time versions.
+        // For defined feature types, conditional queries should reflect either:
+        //  * Enabled if the feature version is specified
+        //  * Disabled if UNAVAILABLE is specified
+        //  * Unknown if no version value is provided
+
         // VERSION=1
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, -1)).isTrue();
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WATCH, 0)).isTrue();
@@ -124,15 +127,19 @@
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 0)).isTrue();
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_WIFI, 100)).isFalse();
 
-        // VERSION=-1
-        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, -1)).isTrue();
+        // VERSION=UNAVAILABLE
+        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, -1)).isFalse();
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 0)).isFalse();
         assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_VULKAN, 100)).isFalse();
 
-        // DISABLED
-        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, -1)).isFalse();
-        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isFalse();
-        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 100)).isFalse();
+        // VERSION=
+        when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTO, 0)).thenReturn(false);
+        assertThat(RoFeatures.hasFeatureAuto(mContext)).isFalse();
+        when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTO, 0)).thenReturn(true);
+        assertThat(RoFeatures.hasFeatureAuto(mContext)).isTrue();
+        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, -1)).isNull();
+        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 0)).isNull();
+        assertThat(RoFeatures.maybeHasFeature(PackageManager.FEATURE_AUTO, 100)).isNull();
 
         // For feature APIs without an associated feature definition, conditional queries should
         // report null, and explicit queries should report runtime-defined versions.
@@ -148,5 +155,6 @@
         assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", -1)).isNull();
         assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", 0)).isNull();
         assertThat(RoFeatures.maybeHasFeature("com.arbitrary.feature", 100)).isNull();
+        assertThat(RoFeatures.maybeHasFeature("", 0)).isNull();
     }
 }