[PATCH] D48626: New option -fwindows-filesystem, affecting #include paths.

[Martin Storsjö via Phabricator via cfe-commits]

mstorsjo added a comment.

In https://reviews.llvm.org/D48626#1146282, @simon_tatham wrote:

> Although, come to think of it, that's not good enough, because if you have multiple directories on your include //path// then you expect a lot of lookups to fail for reasons that have nothing to do with case. Say, if you compile with `-Ifoo -Ibar`, then every include of a file intended to be found in `bar` will force lots of pointless directory enumeration in `foo` when the initial lookup there doesn't find the file. Hmmm. That suggests to me that perhaps this ought not to be a //global// `-ffudge-my-paths` type option applying to all include directories, and instead perhaps it should be a new kind of `-I` option, so that only lookups relative to that particular include-path directory would get the unusual semantics. What do people think?


The cases where I would have needed this (the windows sdk), I'm not specifying that path explicitly via `-I` directives, but implicitly via the `INCLUDE` env variable, but perhaps limiting this to the directories known to have problematic case could be helpful performance wise.

Otherwise I guess this would need to go on a higher level in the algorithm; first check all directories in a fully case sensitive manner, just like today. And if that fails (and we'd have a real failure that we'd otherwise return to the caller), redo it all with case insensitivity. I think that would be the best performance wise, but that makes for much messier integration...


Repository:
  rC Clang

https://reviews.llvm.org/D48626