title: ModuleMap: How can I set a relative path for the umbrella header?
body: <p>I am working with the Swift Package Manager. I have a project which I can successfully build via "swift build". I have created an Xcode project via  "swift package generate-xcodeproj". When I open the project in Xcode it builds successfully.</p>
  
  <p>The Xcode project includes two modules A and B.</p>
  
  <p>Module A has the following map:</p>
  
  <pre><code>module ModuleA {
      umbrella header "/Users/Robert/Temp/MyProject/Sources/ModuleA/include/ModuleA.h"
      link "ModuleA"
      export *
  }
  </code></pre>
  
  <p>Module B depends upon A and has the following import:</p>
  
  <pre><code>import ModuleA
  </code></pre>
  
  <p>So far so good; everything builds successfully. Now I want to change the module map so that it uses a relative path, such as:</p>
  
  <pre><code>module ModuleA {
      umbrella header "ModuleA.h"
      link "ModuleA"
      export *
  }
  </code></pre>
  
  <p>However, when I do that I cannot get Module B to build: Error - Umbrella header 'ModuleA.h' not found. I have tried everything that I can think of in Build Settings -> Search Paths -> Header Search Paths and User Header Search Paths. I've found similar issues online, here and elsewhere, and have tried what I read but so far no go.</p>
  
  <p>This has reached the hair pulling stage. Any advice will be much appreciated!</p>