[PATCH] D37299: [Modules] Add ability to specify module name to module file mapping in a file

[Boris Kolpackov via Phabricator via cfe-commits]

boris added a comment.

Hi Richard,

Thanks for still entertaining the idea. Yes, I believe, in order to support modules (TS) the build system will have to extract module (and header while at it) dependency information prior to compilation rather than as a byproduct of compilation (which is how most build systems do it now). I've written on how all this can work (as well as the support that would be required from the compiler) here:

https://build2.org/article/cxx-modules-misconceptions.xhtml#build

FWIW, we do it this way in build2 (and already have a .d file that we would like to reuse) and get 3x speedup using Clang on a modularized build. Also Gaby told me that he is working on a tool for VC that will do extraction of header and module dependency information (as a single preprocessor pass).


https://reviews.llvm.org/D37299