aaron.ballman added a subscriber: Endill.
aaron.ballman added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:4263-4264
+ // CWG2311: T{ prvalue_of_type_T } is not eligible for copy elision
+ // Make this an elision if this won't call an initializer-list
constructor
+ // (Always on an aggregate type or check constructors first)
+ CopyElisionPossible = true;
----------------
================
Comment at: clang/lib/Sema/SemaInit.cpp:4334
+ case OR_No_Viable_Function: // Possible if you try to initialize from a
+ // volatile prvalue
+ case OR_Ambiguous:
----------------
================
Comment at: clang/lib/Sema/SemaInit.cpp:4337
+ // This was never going to be an initializer-list constructor
+ // so it should be elided
+ ElideConstructor();
----------------
================
Comment at: clang/lib/Sema/SemaInit.cpp:4342
+ // If this deleted constructor was not an initializer-list constructor
+ // we should elide it
+ if (!S.isInitListConstructor(Best->Function)) {
----------------
================
Comment at: clang/lib/Sema/SemaInit.cpp:4249-4250
InitializedEntity::EK_LambdaToBlockConversionBlockElement &&
- UnwrappedArgs.size() == 1 && UnwrappedArgs[0]->isPRValue() &&
- S.Context.hasSameUnqualifiedType(UnwrappedArgs[0]->getType(), DestType))
{
+ Args.size() == 1 && Args[0]->isPRValue() &&
+ S.Context.hasSameUnqualifiedType(Args[0]->getType(), DestType)) {
// Convert qualifications if necessary.
----------------
MitalAshok wrote:
> MitalAshok wrote:
> > This change unfortunately exposes the still-open [[
> > https://wg21.link/CWG2311 | CWG2311 ]] but allows `T{ object_of_type_T }`
> > to consider user declared constructors.
> >
> > I am working on a separate fix for CWG2311 (Consider constructors as below,
> > but then if the chosen constructor is not an initializer-list constructor,
> > elide it).
> >
> Fix will be here: https://reviews.llvm.org/D156062
>
> `auto{ prvalue }` will elide a copy for aggregate types again. It will do so
> after checking constructors for non-aggregate classes now.
As this was abandoned in favor of doing the fix here, the patch title, summary,
and release notes should all be updated to talk about CWG2311.
================
Comment at: clang/test/CXX/drs/dr23xx.cpp:54
+void test() {
+ // Ensure none of these expressions try to call a move constructor
+ T a = T{T(0)};
----------------
================
Comment at: clang/test/CXX/drs/dr23xx.cpp:9
+namespace std {
+ __extension__ typedef __SIZE_TYPE__ size_t;
+
----------------
MitalAshok wrote:
> cor3ntin wrote:
> >
> Wouldn't work in c++98 mode this file is being run in. I've copied this from
> other tests in this directory. I guess I can put a `#if __cplusplus >=
> 201103L` instead?
The current form seems fine to me.
================
Comment at: clang/test/CXX/drs/dr23xx.cpp:50
+namespace dr2311 {
+#if __cplusplus >= 201707L
----------------
MitalAshok wrote:
> cor3ntin wrote:
> > the dr status html page is generated automatically by leaving a magic
> > comment here - and then running `clang/www/make_cxx_dr_status`
> CWG2311 is still open, but clang did support list-initialization elision
> before this patch. The committee still needs to decide how exactly this
> elision is going to work, which might be different from how this patch
> implements it, so hesitant to mark this as done.
CC @Endill -- do we have a special marking for "issue still open in WG21, but
we implement the current suggested resolution?"
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D156032/new/
https://reviews.llvm.org/D156032
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