erik.pilkington added inline comments.
================
Comment at: clang/lib/Lex/ModuleMap.cpp:1198-1203
+ // If the header in the module map refers to a symlink, Header.Entry
+ // refers to the actual file. The callback should be notified of both.
+ if (!FullPathAsWritten.empty() &&
+ !FullPathAsWritten.equals(Header.Entry->getName())) {
+ Cb->moduleMapAddHeader(FullPathAsWritten, Mod->IsSystem, Imported);
+ }
----------------
vsapsai wrote:
> vsapsai wrote:
> > It is strange but after removing this part the tests are still passing. I
> > suspect the code is correct but the test allows some roundabout way to add
> > symlink to dependencies. In my experiments only
> > `DFGMMCallback::moduleMapAddHeader` affects the tests. Is it expected?
> Looks like you have 3 cases:
>
> 1. Add all files in module map to dependencies, even if a file isn't
> `#include`d anywhere (this turned out to be `link.h`).
> 2. For `-fmodule-file` replace header files in dependencies with .pcm file
> (that's what `Imported` achieves).
> 3. Some scenario with symlinks. Here I haven't found a representative test
> case.
3 and 1 should be the same; the problem is that a `FileEntry`'s name mutates
over the course of the compile to refer to the most recent reference to it.
(see FileManager::getFile() and the FIXME from 2007). This puts us in a pretty
awkward position here: we're trying to recover the set of symlinks that clang
used to refer to this file, but I think that that information is lost in the
general case. The Right Thing To Do is probably to actually track that
somewhere. I think we could also probably work around this by attaching the
DependencyFileGenerator callback to the module builder thread, in which case
we'd be able to ensure we use the most-recent version of a `FileEntry`.
I'll keep trying to get a reproducer for this, but FYI you can check it out in
action for the file `ncurses.h` in the SDK.
https://reviews.llvm.org/D53522
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