Fix crash in mergeListProperties

The value of a property to be merged may be a reference to a variable.
When we first create an attribute for a makefile variable (e.g. we
create 'android_static_libs' from LOCAL_STATIC_ANDROID_LIBRARIES), we
set its type correctly. However, reparse in bpfix erases this
information, so by the time 'android_static_libs' attribute is to be
merged with 'static_libs', it has no type and merge occurs. It isn't
easy to fix properly, so just don't merge in such case, Soong will
complain and it will be fixed manually.

Fixes: 125519127
Test: unit tests in androidmk_test.go
Change-Id: Ic66d7ab686a2fdde987f32e2b204c72d9bf0d026

androidmk/cmd/androidmk/androidmk_test.go

@@ -1073,6 +1073,25 @@ vts_config {
 		expected: `
 // Comment line 1 \
 // Comment line 2
+`,
+	},
+	{
+		desc: "Merge with variable reference",
+		in: `
+include $(CLEAR_VARS)
+LOCAL_MODULE := foo
+LOCAL_STATIC_ANDROID_LIBRARIES := $(FOO)
+LOCAL_STATIC_JAVA_LIBRARIES := javalib
+LOCAL_JAVA_RESOURCE_DIRS := $(FOO)
+include $(BUILD_PACKAGE)
+`,
+		expected: `
+android_app {
+	name: "foo",
+	static_libs: FOO,
+	static_libs: ["javalib"],
+	java_resource_dirs: FOO,
+}
 `,
 	},
 }

bpfix/bpfix/bpfix.go

@@ -786,6 +786,14 @@ func mergeMatchingProperties(properties *[]*parser.Property, buf []byte, patchli
 }
 
 func mergeProperties(a, b *parser.Property, buf []byte, patchlist *parser.PatchList) error {
+	// The value of one of the properties may be a variable reference with no type assigned
+	// Bail out in this case. Soong will notice duplicate entries and will tell to merge them.
+	if _, isVar := a.Value.(*parser.Variable); isVar {
+		return nil
+	}
+	if _, isVar := b.Value.(*parser.Variable); isVar {
+		return nil
+	}
 	if a.Value.Type() != b.Value.Type() {
 		return fmt.Errorf("type mismatch when merging properties %q: %s and %s", a.Name, a.Value.Type(), b.Value.Type())
 	}