[PATCH] D109128: [VFS] Use original path when falling back to external FS

[Volodymyr Sapsai via Phabricator via cfe-commits]

vsapsai added a comment.

In D109128#2999846 <https://reviews.llvm.org/D109128#2999846>, @dexonsmith wrote:

> In D109128#2997588 <https://reviews.llvm.org/D109128#2997588>, @JDevlieghere wrote:
>
>> Keith and I discussed this offline. My suggestion was to do the following:
>>
>> 1. Check the overlay for the canonicalized path
>> 2. Check the fall-through for the canonicalized path
>> 3. Check the fall-through for the original path
>
> I'm not sure it's correct to do (3) at all...

I might have missed that but what use case are we addressing by avoiding the usage of the original path for the fall-through file system? Because we have not only a problem with names reported back but also canonicalization can break symlinks with relative paths. For example, for the layout

  |- packages
  |  |- a
  |  |  `- include
  |  `- b
  |     `- include
  `- include -> packages/a/include

`-I ./include/../../b/include` doesn't work if you have VFS, even an empty one.


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  https://reviews.llvm.org/D109128/new/

https://reviews.llvm.org/D109128