aaron.ballman added inline comments.
================
Comment at: clang-tidy/modernize/DeprecatedFunctionalCheck.cpp:48-54
+ } else if (const auto *const Call =
+ Result.Nodes.getNodeAs<CallExpr>("ptr_fun_call")) {
+ diag(Call->getLocStart(), Message) << "'std::ptr_fun'";
+ } else if (const auto *const Call =
+ Result.Nodes.getNodeAs<CallExpr>("mem_fun_call")) {
+ diag(Call->getLocStart(), Message) << "'std::mem_fun'";
+ }
----------------
alexfh wrote:
> alexfh wrote:
> > aaron.ballman wrote:
> > > massberg wrote:
> > > > aaron.ballman wrote:
> > > > > I think that this code should be generalized (same with the matchers)
> > > > > so that you match on `hasAnyName()` for the function calls and use
> > > > > `CallExpr::getCalleeDecl()` to get the declaration. e.g.,
> > > > > ```
> > > > > if (const auto *Call = Result.Nodes.getNodeAs<CallExpr>("blech")) {
> > > > > if (const Decl *Callee = Call->getCalleeDecl())
> > > > > diag(Call->getLocStart(), Message) << Calleee;
> > > > > }
> > > > > ```
> > > > > This way you can add more named without having to add extra logic for
> > > > > the diagnostics.
> > > > I generalized the code and the matcher.
> > > > When we use
> > > > ```
> > > > << cast<NamedDecl>(Callee);
> > > > ```
> > > > we get the template arguments in the name , e.g. `ptr_fun<int, int>`,
> > > > so I chose to use `getQualifiedNameAsString`.
> > > > If there is there a better way to get the function name without
> > > > template arguments I appreciate any suggestions.
> > > >
> > > >
> > > Nope, in that case, your code is correct. However, we generally provide
> > > the template arguments in diagnostics. I see @alexfh was asking for them
> > > to be removed as not being useful, but I'm not certain I agree with his
> > > rationale. Yes, all instances are deprecated and thus the template
> > > arguments don't discern between good and bad cases, but showing the
> > > template arguments is also consistent with the other diagnostics we emit.
> > > For instance, other "deprecated" diagnostics also emit the template
> > > arguments. I'm not certain we should be inconsistent with the way we
> > > produce diagnostics, but I'll defer to Alex if he still feels strongly
> > > about leaving them off here.
> > Indeed, -Wdeprecated-declarations warnings print template arguments.
> > Moreover, they seem to be issued only on instantiations, see
> > https://godbolt.org/g/W563gw.
> >
> > But I have a number of concerns with template arguments in the deprecation
> > warnings:
> >
> > 1. The note attached to the warning lies. Consider a warning from the test
> > above:
> > ...
> > <source>:11:1: warning: 'B<int>' is deprecated: bbb
> > [-Wdeprecated-declarations]
> > B<int> e;
> > ^
> > <source>:7:10: note: 'B<int>' has been explicitly marked deprecated here
> > struct [[deprecated("bbb")]] B {};
> >
> > But `B<int>` hasn't been explicitly marked deprecated, only the template
> > definition of `B` has been. Template arguments are important in the case of
> > the explicit template specialization `A<int>` in the same example, but not
> > in cases where the template definition was marked deprecated, since
> > template arguments only add noise and no useful information there.
> > 2. Warnings can easily become unreadable: https://godbolt.org/g/AFdznH
> > 3. Certain coding patterns can result in numerous deprecation warnings
> > differing only in template arguments: https://godbolt.org/g/U2JCbG.
> > Clang-tidy can deduplicate warnings, if they have identical text and
> > location, but adding template arguments to the message will prevent
> > deduplication. I've seen a case where thousands of deprecation warnings
> > were generated for a single line in a widely used header.
> >
> > So yes, I feel strongly about leaving off template arguments in case the
> > whole template was marked deprecated. I think it would be the right thing
> > to do for the -Wdeprecated-declarations diagnostic as well.
> s/leaving off/leaving out/
> The note attached to the warning lies.
No it doesn't? The attribute is inherited from the primary template unless your
explicit specialization *removes* the attribute. https://godbolt.org/g/ZuXZds
> Warnings can easily become unreadable
This is true of all template diagnostics and isn't specific to clang-tidy's
treatment of them.
> I've seen a case where thousands of deprecation warnings were generated for a
> single line in a widely used header.
This sounds more worrying, but at the same time, your link behaving by design
and doing what I would want it to do. The presence of the deprecated primary
template isn't what gets diagnosed, it's the *uses* of the deprecated entity.
This is called out explicitly in [dcl.attr.deprecated]p4.
> So yes, I feel strongly about leaving off template arguments in case the
> whole template was marked deprecated. I think it would be the right thing to
> do for the -Wdeprecated-declarations diagnostic as well.
I would be strongly opposed to that change to -Wdeprecated-declarations.
We may be at an impasse here, but my viewpoint is unchanged -- I think removing
the template arguments is inconsistent with other diagnostics. I'll defer to
you on this, but I think it's a mistake and definitely do not want to see it
used as precedent.
https://reviews.llvm.org/D42730
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