rusyaev-roman added inline comments.
================
Comment at: clang/lib/Sema/Scope.cpp:152-154
+ // Consider the variable as NRVO candidate if the return slot is available
+ // for it in the current scope, or if it can be available in outer scopes.
+ NRVO = CanBePutInReturnSlot ? VD : nullptr;
----------------
ChuanqiXu wrote:
> What if NRVO contains a value already? It is possible due to the value of
> NRVO could be set by its children.
Actually this is intention. If the parent has already NRVO candidate, then it
should be invalidated (or not). Let's consider the following examples:
```
X foo(bool b) {
X x;
X y;
if (b)
return x;
else
return y; // when we process this return statement, the parent has
already NRVO and it will be invalidated (this is correct behavior)
}
```
```
X foo(bool b) {
X x;
if (b)
return x;
X y;
// when we process this return statement, the parent has already NRVO and it
WON't be invalidated
// (this is correct behavior), because a return slot will be available for
it
return y;
}
```
```
X foo(bool b) {
X x;
if (b)
return x;
// when we process this return statement, the parent has already NRVO and it
WON't be invalidated (this is correct behavior)
return x;
}
```
```
X foo(bool b, X x) {
X y;
if (b)
return x;
// when we process this return statement, the parent contains nullptr
(invalid candidate) and it will be invalidated (this is correct behavior)
return y;
}
```
```
X foo(bool b, X x) {
if (b)
return x;
X y;
// when we process this return statement, the parent contains nullptr
(invalid candidate) and it WON't be invalidated (this is correct behavior)
return y;
}
```
================
Comment at: clang/lib/Sema/Scope.cpp:184-185
+ // }
+ if (!getEntity())
+ getParent()->NRVO = *NRVO;
}
----------------
ChuanqiXu wrote:
> There is a similar problem. It looks not right if the NRVO of the parent owns
> a value already.
Yes, this is intention. You can take a look at the above comment.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D119792/new/
https://reviews.llvm.org/D119792
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