rsmith added inline comments.
================
Comment at: lib/Analysis/CFG.cpp:1435
/// extended by a local reference with the given initializer.
static QualType getReferenceInitTemporaryType(ASTContext &Context,
const Expr *Init,
----------------
NoQ wrote:
> rsmith wrote:
> > Can you replace this with `Expr::skipRValueSubobjectAdjustments`? That's
> > how we compute this elsewhere. (You'll need to skip a top-level
> > `ExprWithCleanups` and check for the search terminating in a
> > `MaterializeTemporaryExpr` yourself, but this will reduce duplication and
> > fix a couple more cases this function is getting wrong).
> Hmm, right, ok, yeah. I'm in no rush with this one, so i'll spend some time
> trying to understand what //rvalue// adjustments do we still have after
> rC288563.
We still have to deal with rvalue adjustments in C++98 compilations, because we
don't create xvalue `MaterializeTemporaryExpr` nodes there (because C++98
doesn't have xvalues). I think if/when we carry out the plan to remove
`CXXBindTemporaryExpr`, skipping rvalue adjustments will only be interesting to
the code that performs lifetime extension, and everything else can just deal
with the `MaterializeTemporaryExpr` nodes. But for now, you'll need to skip
rvalue adjustments if you want to handle our C++98 ASTs.
As a quick example, take:
```
struct A { int n; };
const int &r = A().*&A::n;
```
... which produces this AST in C++11 onwards:
```
`-VarDecl 0xc2681f0 <col:22, col:46> col:33 r 'const int &' cinit
`-ExprWithCleanups 0xc268b28 <col:37, col:46> 'const int' xvalue
`-ImplicitCastExpr 0xc2689f0 <col:37, col:46> 'const int' xvalue <NoOp>
`-BinaryOperator 0xc2689c8 <col:37, col:46> 'int' xvalue '.*'
|-MaterializeTemporaryExpr 0xc2689b0 <col:37, col:39> 'A' xvalue
extended by Var 0xc2681f0 'r' 'const int &'
| `-CXXTemporaryObjectExpr 0xc2687b0 <col:37, col:39> 'A' 'void ()
noexcept' zeroing
`-UnaryOperator 0xc268990 <col:42, col:46> 'int A::*' prefix '&' cannot
overflow
`-DeclRefExpr 0xc268928 <col:43, col:46> 'int' lvalue Field 0xc268148
'n' 'int'
```
... but produces this in C++98 mode (which I think this function will mishandle
because it doesn't know how to look through the binary `.*` operator):
```
`-VarDecl 0xcd61c90 <col:22, col:46> col:33 r 'const int &' cinit
`-ExprWithCleanups 0xcd62398 <col:37, col:46> 'const int' lvalue
`-MaterializeTemporaryExpr 0xcd622a8 <col:37, col:46> 'const int' lvalue
extended by Var 0xcd61c90 'r' 'const int &'
`-BinaryOperator 0xcd62280 <col:37, col:46> 'int' '.*'
|-CXXTemporaryObjectExpr 0xcd62080 <col:37, col:39> 'A' 'void ()
throw()' zeroing
`-UnaryOperator 0xcd62260 <col:42, col:46> 'int A::*' prefix '&' cannot
overflow
`-DeclRefExpr 0xcd621f8 <col:43, col:46> 'int' lvalue Field 0xcd61be8
'n' 'int'
```
Repository:
rC Clang
https://reviews.llvm.org/D44238
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