Xcode INSTALL_PATH and framework paths

[Aaron Madlon-Kay]

Hi all.

I am working on a portfile for Sequel Pro (https://sequelpro.com/) and
am reaching the limits of my understanding of the Xcode build system.

Sequel Pro contains several framework subprojects, which get built
along with the main target. If I build the project normally outside of
MacPorts then the frameworks get built and placed alongside the app,
but also copied to into the app at Sequel Pro.app/Contents/Frameworks;
`otool -L` on the main binary shows they are relatively linked as e.g.
@executable_path/../Frameworks/foo.

However when I build in MacPorts, INSTALL_PATH is automatically set to
${applications_dir}, and this apparently causes the main binary to
look for the frameworks at e.g. /Applications/MacPorts/foo instead of
@executable_path/../Frameworks/foo. Thus when I destroot just Sequel
Pro.app it can no longer find the framework and blows up on launch
(plus MacPorts correctly detects it as a broken binary).

What is the correct way to handle this?

Thanks,
Aaron