[PATCH] [modules] PR20507: Avoid silent textual inclusion.

[Sean Silva]

On Fri, Jun 19, 2015 at 4:31 PM, Richard Smith <richard at metafoo.co.uk>
wrote:

> On Fri, Jun 19, 2015 at 4:18 PM, Sean Silva <chisophugis at gmail.com> wrote:
>
>> ================
>> Comment at: include/clang/Basic/DiagnosticLexKinds.td:626
>> @@ -625,1 +625,3 @@
>> +def note_implicit_top_level_module_import_here : Note<
>> +  "submodule of top-level module '%0' implicitly imported here">;
>>  def warn_uncovered_module_header : Warning<
>> ----------------
>> benlangmuir wrote:
>> > I'd just drop "submodule of top-level ".
>> I think it's an important qualification because the module that was in
>> fact imported is not %0. %0 is the top-level module containing it, and the
>> error is because some submodule of %0 (perhaps the one being imported,
>> perhaps not) has the missing file.
>>
>> From a user's perspective: "The header I included didn't ask for %0 to be
>> imported. It asked for this submodule of it". Ideally we would be able to
>> somehow communicate the "unity build" aspect of top-level modules for this
>> to make sense, but I couldn't find a way to fit all that in a diagnostic.
>>
>> Does that make sense?
>
>
> We use this kind of introductory text for a diagnostic produced within a
> module:
>
> In module '<top-level module>' imported from <use of submodule>:
>
> ... and a similar note for a diagnostic that occurs while implicitly
> building a module, so removing the "submodule of top-level" from your
> diagnostic would be consistent with that. In fact, I'm not sure your note
> is necessary; don't we already produce a "While building <top-level module>
> imported from <somewhere>" message prior to emitting the error message?
>

Are you saying that these things automatically happen? The test output of
test/Modules/missing-header.cpp with the current patch is as follows:

/Users/Sean/pg/llvm/tools/clang/test/Modules/Inputs/submodules/module.map:15:27:
error: header 'missing.h' not found

  module missing { header "missing.h" }

                          ^

/Users/Sean/pg/llvm/tools/clang/test/Modules/missing-header.cpp:10:10:
note: submodule of top-level module 'missing_headers' implicitly imported
here

#include "not_missing.h"

         ^

1 error generated.

There doesn't appear to be any "In module ...." or "While building ...".
Under what circumstances are those emitted? Or do I need to add something
to have them be emitted?

-- Sean Silva


>
> http://reviews.llvm.org/D10423
>>
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