Clang modules: collect exports recursively
This change makes Module::buildVisibleModulesCache() collect exported modules
recursively.
While computing a set of exports, getExportedModules() iterates over the set of
imported modules and filters it. But it does not consider the set of exports
of those modules -- it is the responsibility of the caller to do this.
Here is a certain instance of this issue. Module::isModuleVisible says that
CoreFoundation.CFArray submodule is not visible from Cocoa. Why?
- Cocoa imports Foundation.
- Foundation has an export restriction: "export *".
- Foundation imports CoreFoundation. (Just the top-level module.)
- CoreFoundation exports CoreFoundation.CFArray.
To decide which modules are visible from Cocoa, we collect all exported modules
from immediate imports in Cocoa:
> visibleModulesFro(Cocoa) = exported(Foundation) + exported(CoreData) + exported(AppKit)
To find out which modules are exported, we filter imports according to
restrictions:
> exported(Foundation) = filterByModuleMapRestrictions(imports(Foundation))
Because Foundation imports CoreFoundation (not CoreFoundation.CFArray), the
CFArray submodule is considered not exported from Foundation, and is not
visible from Cocoa (according to Module::isModuleVisible).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193815
91177308-0d34-0410-b5e6-
96231b3b80d8