Support LOCAL_SDK_VERSION := core_current

core_current is a pseudo SDK version which is a core Java API subset of
the Android API. It is expected to be mainly used for external Java
projects which are agnostic to Android; such as junit, guava, etc.

A module built with this SDK version can only link to java modules of
the same kind. It can't depend on modules built with LOCAL_SDK_VERSION
:= current or without LOCAL_SDK_VERSION.

Bug: 72206056
Test: m -j
Change-Id: I34a9696393aa6704fd6684a40ea5b05d3fb46b23
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index 176a01d..04eb78e 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -71,6 +71,9 @@
   else ifeq ($(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS),test_current)
     LOCAL_JAVA_LIBRARIES := android_test_stubs_current $(LOCAL_JAVA_LIBRARIES)
     $(full_target): PRIVATE_BOOTCLASSPATH := $(call java-lib-files, android_test_stubs_current)
+  else ifeq ($(LOCAL_SDK_VERSION)$(TARGET_BUILD_APPS),core_current)
+    LOCAL_JAVA_LIBRARIES := core.current.stubs $(LOCAL_JAVA_LIBRARIES)
+    $(full_target): PRIVATE_BOOTCLASSPATH := $(call java-lib-files, core.current.stubs)
   else
     ifneq (,$(call has-system-sdk-version,$(LOCAL_SDK_VERSION)))
       ifeq (,$(TARGET_BUILD_APPS))
@@ -81,8 +84,12 @@
         $(full_target): PRIVATE_BOOTCLASSPATH := $(call java-lib-files, sdk_v$(LOCAL_SDK_VERSION))
       endif
     else
-      LOCAL_JAVA_LIBRARIES := sdk_v$(LOCAL_SDK_VERSION) $(LOCAL_JAVA_LIBRARIES)
-      $(full_target): PRIVATE_BOOTCLASSPATH := $(call java-lib-files, sdk_v$(LOCAL_SDK_VERSION))
+      # core_<ver> is subset of <ver>. Instead of defining a prebuilt lib for core_<ver>,
+      # use the stub for <ver> when building for apps.
+      _version := $(patsubst core_%,%,$(LOCAL_SDK_VERSION))
+      LOCAL_JAVA_LIBRARIES := sdk_v$(_version) $(LOCAL_JAVA_LIBRARIES)
+      $(full_target): PRIVATE_BOOTCLASSPATH := $(call java-lib-files, sdk_v$(_version))
+      _version :=
     endif
   endif
 else