Emit error if expression cannot be evaluated to boolean during androidmk conversion

Fixes: 127517965
Test: run androidmk /sdx/asmundak/repos/iandr/vendor/google_paintbox/amber/camera/tests/Android.mk
Change-Id: If7b6bcb88bb8f25d3f421a847750a82b1e50833e

androidmk/androidmk/android.go

@@ -383,11 +383,15 @@ func local32BitOnly(ctx variableAssignmentContext) error {
 	if err != nil {
 		return err
 	}
-	if val.(*bpparser.Bool).Value {
+	boolValue, ok := val.(*bpparser.Bool)
+	if !ok {
+		return fmt.Errorf("value should evaluate to boolean literal")
+	}
+	if boolValue.Value {
 		thirtyTwo := &bpparser.String{
 			Value: "32",
 		}
-		setVariable(ctx.file, false, ctx.prefix, "compile_multilib", thirtyTwo, true)
+		return setVariable(ctx.file, false, ctx.prefix, "compile_multilib", thirtyTwo, true)
 	}
 	return nil
 }

androidmk/androidmk/androidmk_test.go

@@ -1338,6 +1338,25 @@ android_app_import {
 	},
 	apk: "foo.apk",
 
+}
+`,
+	},
+	{
+		desc: "undefined_boolean_var",
+		in: `
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES:= a.cpp
+LOCAL_MODULE:= test
+LOCAL_32_BIT_ONLY := $(FLAG)
+include $(BUILD_EXECUTABLE)
+`,
+		expected: `
+cc_binary {
+    name: "test",
+    srcs: ["a.cpp"],
+    // ANDROIDMK TRANSLATION ERROR: value should evaluate to boolean literal
+    // LOCAL_32_BIT_ONLY := $(FLAG)
+
 }
 `,
 	},