This patch changes two things:
a) Allow a header to be part of multiple modules. The reasoning is that
in existing codebases that have a module-like build system, the same
headers might be used in several build targets. Simple reasons might be
that they defined different classes that are declared in the same
header. Supporting a header as a part of multiple modules will make the
transistion easier for those cases. A later step in clang can then
determine whether the two modules are actually compatible and can be
merged and error out appropriately. The later check is similar to what
needs to be done for template specializations anyway.
b) Allow modules to be stored in a directory tree separate from the
headers they describe.
Review: http://llvm-reviews.chandlerc.com/D1951
llvm-svn: 193151
This patch is the first step to make module-map-files modular (instead
of requiring a single "module.map"-file per include directory). This
step adds a new "extern module" declaration that enables
module-map-files to reference one another along with a very basic
implementation.
The next steps are:
* Combine this with the use-declaration (from
http://llvm-reviews.chandlerc.com/D1546) in order to only load module
map files required for a specific compilation.
* Add an additional flag to start with a specific module-map-file (instead
of requiring there to be at least one "module.map").
Review: http://llvm-reviews.chandlerc.com/D1637
llvm-svn: 190497
Daniel Jasper