[PATCH] D26118: [clang-tidy] Change readability-redundant-member-init to get base type from constructor

[Aaron Ballman via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: clang-tidy/readability/RedundantMemberInitCheck.cpp:57
            "initializer for base class %0 is redundant")
-          << Init->getTypeSourceInfo()->getType()
+          << Construct->getType()
           << FixItHint::CreateRemoval(Init->getSourceRange());
----------------
malcolm.parsons wrote:
> malcolm.parsons wrote:
> > aaron.ballman wrote:
> > > malcolm.parsons wrote:
> > > > aaron.ballman wrote:
> > > > > Why is it more correct to use the CXXConstructExpr type information rather than the CXXCtorInitializer?
> > > > Something to do with templates and namespaces.
> > > > 
> > > > In the bug report, `CXXCtorInitializer` had type `std::__1::bitset<128>` and `CXXConstructExpr` had type `std::bitset<MAX_SUBTARGET_FEATURES>`.
> > > > 
> > > > I don't know why.
> > > I believe it's because `__1` is an inline namespace, and the printing policy matters. IIRC, there's the `SuppressUnwrittenScope` policy data member, that if you set it to true, it won't print the inline or anonymous namespace when printing types.
> > > 
> > > We should understand why there's a difference before applying this change. I think using the CXXCtorInitializer's type is more correct than using the CXXConstructExpr's type (due to implicit type conversions). Given that the printing policy controls whether inline namespaces are printed, I would have expected these both to print without the inline namespace (the type changed, but not the printing policy) -- the fact that the behavior differs makes me worried there's a bug somewhere else and this fix is masking it.
> > The difference isn't just the scope; `MAX_SUBTARGET_FEATURES` became `128` too.
> > 
> > Looking at `Sema::BuildMemInitializer()` didn't help me.
> The lookup of the base type has a Path with sugared type, but the Decl found has a canonical type.
So then you get the same behavior by getting the canonical type from `Init->getTypeSourceInfo()->getType()`?


https://reviews.llvm.org/D26118