[PATCH] D27751: [LLVM] Use after move bug fixes

[Piotr Padlewski via Phabricator via llvm-commits]

Prazek added a reviewer: lhames.
Prazek added inline comments.


================
Comment at: lib/Object/Error.cpp:94
     return Err2;
-  return Err;
+  return Err; // Use after move, not sure how to fix it.
 }
----------------
mehdi_amini wrote:
> @lhames : can you look at this?
ping


================
Comment at: tools/llvm-profdata/llvm-profdata.cpp:53
   if (E.isA<InstrProfError>()) {
     handleAllErrors(std::move(E), [&](const InstrProfError &IPE) {
       instrprof_error instrError = IPE.get();
----------------
mehdi_amini wrote:
> mehdi_amini wrote:
> > vsk wrote:
> > > mehdi_amini wrote:
> > > > I'm wondering why there is a check for error before calling handleAllErrors here? (@lhames while you're at it...)
> > > If it is an instrprof error, we'd like the chance to inspect it and display an additional hint, instead of simply printing out a string representation of the error.
> > The check still does not seem idiomatic to me, it could be instead:
> > 
> > ```
> >     E = handleErrors(std::move(E), [&](const InstrProfError &IPE) {
> >      instrprof_error instrError = IPE.get();
> >       StringRef Hint = "";
> >       if (instrError == instrprof_error::unrecognized_format) {
> >         // Hint for common error of forgetting -sample for sample profiles.
> >         Hint = "Perhaps you forgot to use the -sample option?";
> >       }
> >       exitWithError(IPE.message(), Whence, Hint);
> >     });
> >     exitWithError(toString(std::move(E)), Whence);
> > ````
> I *think* you can also write:
> 
> ```
>     handleAllErrors(std::move(E),
>       [&](const InstrProfError &IPE) {
>        instrprof_error instrError = IPE.get();
>         StringRef Hint = "";
>         if (instrError == instrprof_error::unrecognized_format) {
>           // Hint for common error of forgetting -sample for sample profiles.
>           Hint = "Perhaps you forgot to use the -sample option?";
>         }
>         exitWithError(IPE.message(), Whence, Hint);
>       },
>       [&](const Error &E) {
>         exitWithError(toString(E), Whence);
>     });
> ````
Both seems fine, but I guess only the first one will get rid of the warning, because compiler will not be able to reason that handleErrors is noreturn because each lambda is noreturn


https://reviews.llvm.org/D27751