NoQ 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,
----------------
rsmith wrote:
> 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'
> ```
Aha, yay, thanks, i'll add this one, and also it seems that CFG and Analyzer
C++ tests need way more different `-std=` run-lines :)
Repository:
rC Clang
https://reviews.llvm.org/D44238
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