aaronpuchert added inline comments.
================
Comment at: clang/lib/Sema/SemaStmt.cpp:3102
+ // C++20 [class.copy.elision]p3:
+ // ...either a non-volatile object or an rvalue reference to a
non-volatile object type...
+ if (!(CESK & CES_AllowRValueReferenceType))
----------------
This is probably over the line limit, maybe try to reflow this as suggested.
================
Comment at: clang/lib/Sema/SemaStmt.cpp:3095
- // ...non-volatile...
- if (VD->getType().isVolatileQualified())
- return false;
-
- // C++20 [class.copy.elision]p3:
- // ...rvalue reference to a non-volatile...
- if (VD->getType()->isRValueReferenceType() &&
- (!(CESK & CES_AllowRValueReferenceType) ||
- VD->getType().getNonReferenceType().isVolatileQualified()))
+ if (VD->getType()->isObjectType()) {
+ // C++17 [class.copy.elision]p3:
----------------
mizvekov wrote:
> Quuxplusone wrote:
> > mizvekov wrote:
> > > mizvekov wrote:
> > > > mizvekov wrote:
> > > > > A drive by fix here would be that we already have a VDType in this
> > > > > context, might as well use it even though original for some reason
> > > > > missed it in this part.
> > > > This whole block is also logically equivalent to the much simpler:
> > > > ```
> > > > if (VDType.isReferenceType()) {
> > > > if (!(CESK & CES_AllowRValueReferenceType) ||
> > > > !VDType.isRValueReferenceType())
> > > > return false;
> > > > VDType = VDType.getNonReferenceType()
> > > > }
> > > > if (!VDType.isObjectType() || VDType.isVolatileQualified())
> > > > return false;
> > > > ```
> > > > But you do have to adjust the comments there and adjust the rest to use
> > > > VDType consistently :)
> > > > Also, I think it might be possible to even remove the
> > > > `!VDType.isObjectType() || ` part from my suggestion above, because it
> > > > might be the only option left if it is not a reference anyway.
> > > ```
> > > bool isObjectType() const {
> > > // C++ [basic.types]p8:
> > > // An object type is a (possibly cv-qualified) type that is not a
> > > // function type, not a reference type, and not a void type.
> > > return !isReferenceType() && !isFunctionType() && !isVoidType();
> > > }
> > > ```
> > > So yeah I think you can just make my suggestion be:
> > > ```
> > > if (VDType.isReferenceType()) {
> > > if (!(CESK & CES_AllowRValueReferenceType) ||
> > > !VDType.isRValueReferenceType())
> > > return false;
> > > VDType = VDType.getNonReferenceType()
> > > }
> > > if (VDType.isVolatileQualified())
> > > return false;
> > > ```
> > >
> > >
> > Yeah but I //reaally// don't want to
> > (1) change the meaning of `VDType` in the middle of this function (mantra:
> > "one name = one meaning")
> > (2) get "clever". I don't want to have to think about "Are there any types
> > that are neither object types nor reference types?" (What about function
> > types? What about block types? What about, I dunno, bit-fields?) I want the
> > code to be //obviously correct//, and also to casewise match exactly what
> > the standard says. It says object or rvalue reference type — let's write
> > code that expresses that wording //exactly//.
> How about:
> ```
> QualType VDObjType = VDType;
> if (!VDType.isObjectType()) {
> if (!(CESK & CES_AllowRValueReferenceType) ||
> !VDType.isRValueReferenceType())
> return false;
> VDObjType = VDType.getNonReferenceType();
> }
> if (VDObjType .isVolatileQualified())
> return false;
> ```
> And then `s/VDType/VDObjType/` from here on.
> I think this expresses the meaning of the standard clearly.
That seems like a sensible simplification, the proposed code is indeed a bit
repetitive. I'd go with the original suggestion plus the new variable:
```
QualType VDNonRefType = VDType;
if (VDType.isReferenceType()) {
if (!(CESK & CES_AllowRValueReferenceType) ||
!VDType.isRValueReferenceType())
return false;
VDNonRefType = VDType.getNonReferenceType()
}
if (!VDNonRefType.isObjectType() || VDNonRefType.isVolatileQualified())
return false;
```
or whatever name you find appropriate. Actually it's the type of the
`DeclRefExpr`, isn't it? So maybe `DREType`?
The initialization might be a bit misleading, an alternative would be to not
initialize and have an assignment `VDNonRefType = VDType` in the else branch
instead.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D98971/new/
https://reviews.llvm.org/D98971
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