Test case for https://reviews.llvm.org/D112915 that demonstrates `isImport` needs to be tracked per submodule too.

include-with-broken-unused-header.m

// RUN: rm -rf %t
// RUN: split-file %s %t
// RUN: %clang_cc1 -fsyntax-only -fmodules -fimplicit-module-maps -fmodules-cache-path=%t/modules.cache -F %t/Frameworks %t/test.m

//--- Frameworks/NonModular.framework/Headers/NonModular.h
#ifdef ENUM_VALUE
// Requires to be included inside an enum with macro ENUM_VALUE defined.
ENUM_VALUE(Left, 0),
ENUM_VALUE(Right, 1),
#endif

//--- Frameworks/BrokenImporter.framework/Headers/Empty.h
// empty

//--- Frameworks/BrokenImporter.framework/Headers/Broken.h
// Broken because not defining a required macro, not in correct context and
// importing instead of including. But it shouldn't be a problem as nobody
// includes/imports this broken header.
#import <NonModular/NonModular.h>

//--- Frameworks/BrokenImporter.framework/Modules/module.modulemap
framework module BrokenImporter {
  module Empty {
    header "Empty.h"
  }
  module Broken {
    header "Broken.h"
  }
}

//--- test.m
#import <BrokenImporter/Empty.h>

enum FirstEnum {
#define ENUM_VALUE(name, value) FirstEnum ## name ## Value = value
#include <NonModular/NonModular.h>
#undef ENUM_VALUE
};

int test() {
  return FirstEnumLeftValue;
}