Add support for exporting library dependencies.

We supported `LOCAL_EXPORT_LDLIBS`, but not
`LOCAL_EXPORT_SHARED_LIBRARIES` or `LOCAL_EXPORT_STATIC_LIBRARIES`.

We need this feature to make ndk-build use libunwind with libc++ for
only arm32. This hasn't been a problem thus far because ndk-build
currently doesn't so much as warn about missing dependencies
(android/ndk#208).

Test: ./run_tests.py --filter export-libs
Bug: None
Change-Id: Ib6b326779115cc9f60cc8018a38cb57074f7618b

build/core/definitions.mk

@@ -402,6 +402,8 @@ modules-LOCALS := \
     EXPORT_CPPFLAGS \
     EXPORT_ASMFLAGS \
     EXPORT_LDFLAGS \
+    EXPORT_SHARED_LIBRARIES \
+    EXPORT_STATIC_LIBRARIES \
     EXPORT_LDLIBS \
     EXPORT_C_INCLUDES \
     FILTER_ASM \

build/core/import-locals.mk

@@ -36,6 +36,8 @@ imported_RENDERSCRIPT_FLAGS := $(call module-get-listed-export,$(all_depends),RE
 imported_ASMFLAGS   := $(call module-get-listed-export,$(all_depends),ASMFLAGS)
 imported_C_INCLUDES := $(call module-get-listed-export,$(all_depends),C_INCLUDES)
 imported_LDFLAGS    := $(call module-get-listed-export,$(all_depends),LDFLAGS)
+imported_SHARED_LIBRARIES := $(call module-get-listed-export,$(all_depends),SHARED_LIBRARIES)
+imported_STATIC_LIBRARIES := $(call module-get-listed-export,$(all_depends),STATIC_LIBRARIES)
 
 ifdef NDK_DEBUG_IMPORTS
     $(info Imports for module $(LOCAL_MODULE):)
@@ -46,6 +48,8 @@ ifdef NDK_DEBUG_IMPORTS
     $(info   ASMFLAGS='$(imported_ASMFLAGS)')
     $(info   C_INCLUDES='$(imported_C_INCLUDES)')
     $(info   LDFLAGS='$(imported_LDFLAGS)')
+    $(info   SHARED_LIBRARIES='$(imported_SHARED_LIBRARIES)')
+    $(info   STATIC_LIBRARIES='$(imported_STATIC_LIBRARIES)')
     $(info All depends='$(all_depends)')
 endif
 
@@ -60,6 +64,13 @@ LOCAL_RENDERSCRIPT_FLAGS := $(strip $(imported_RENDERSCRIPT_FLAGS) $(LOCAL_RENDE
 LOCAL_ASMFLAGS := $(strip $(imported_ASMFLAGS) $(LOCAL_ASMFLAGS))
 LOCAL_LDFLAGS    := $(strip $(imported_LDFLAGS) $(LOCAL_LDFLAGS))
 
+__ndk_modules.$(LOCAL_MODULE).STATIC_LIBRARIES += \
+    $(strip $(call strip-lib-prefix,$(imported_STATIC_LIBRARIES)))
+__ndk_modules.$(LOCAL_MODULE).SHARED_LIBRARIES += \
+    $(strip $(call strip-lib-prefix,$(imported_SHARED_LIBRARIES)))
+$(call module-add-static-depends,$(LOCAL_MODULE),$(imported_STATIC_LIBRARIES))
+$(call module-add-shared-depends,$(LOCAL_MODULE),$(imported_SHARED_LIBRARIES))
+
 #
 # The imported include directories are appended to their LOCAL_XXX value
 # (this allows the module to override them)

tests/build/export-libs/jni/Android.mk

@@ -0,0 +1,35 @@
+LOCAL_PATH := $(call my-dir)
+
+# Provides foo.
+include $(CLEAR_VARS)
+LOCAL_MODULE := libfoo
+LOCAL_SRC_FILES := foo.c
+include $(BUILD_STATIC_LIBRARY)
+
+# Provides bar.
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbar
+LOCAL_SRC_FILES := bar.c
+include $(BUILD_SHARED_LIBRARY)
+
+# Provides baz, which needs foo and bar. Since this is a static library, we need
+# to link both libfoo and libbar into any of out callers.
+include $(CLEAR_VARS)
+LOCAL_MODULE := libbaz
+LOCAL_SRC_FILES := baz.c
+# NB: Normally we'd want to add these libraries to LOCAL_STATIC_LIBRARIES and
+# LOCAL_SHARED_LIBRARIES to pick up any exported values from those libraries,
+# but we want to make sure that these exports are used even if nothing depends
+# on the module in question since there are actually two separate places this
+# information needs to be recorded (this problem did come up in testing).
+LOCAL_EXPORT_STATIC_LIBRARIES := libfoo
+LOCAL_EXPORT_SHARED_LIBRARIES := libbar
+include $(BUILD_STATIC_LIBRARY)
+
+# Calls baz, which needs definitions of foo and bar. We get those libraries
+# added to our module even though we only depend on libbaz.
+include $(CLEAR_VARS)
+LOCAL_MODULE := qux
+LOCAL_SRC_FILES := qux.c
+LOCAL_STATIC_LIBRARIES := libbaz
+include $(BUILD_EXECUTABLE)

tests/build/export-libs/jni/bar.c

@@ -0,0 +1 @@
+void bar() {}

tests/build/export-libs/jni/baz.c

@@ -0,0 +1,7 @@
+extern void foo();
+extern void bar();
+
+void baz() {
+  foo();
+  bar();
+}

tests/build/export-libs/jni/foo.c

@@ -0,0 +1 @@
+void foo() {}

tests/build/export-libs/jni/qux.c

@@ -0,0 +1,5 @@
+extern void baz();
+
+int main(int argc, char** argv) {
+  baz();
+}