cjdb updated this revision to Diff 466318.
cjdb retitled this revision from "[clang] adds
`__reference_constructs_from_temporary` and
`__reference_converts_from_temporary`" to "[clang] adds
`__reference_constructs_from_temporary`".
cjdb added a comment.
discards work on `__reference_converts_from_temporary` for now. This feature
isn't as trivial to implement as `__reference_constructs_from_temporary`, so
it's deserving of its own commit. The two features are used exclusively, so
it's not like adding one without the other will lead to an incomplete standard
type.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D135341/new/
https://reviews.llvm.org/D135341
Files:
clang/docs/LanguageExtensions.rst
clang/include/clang/Basic/DiagnosticCommonKinds.td
clang/lib/Lex/PPMacroExpansion.cpp
clang/lib/Parse/ParseDeclCXX.cpp
clang/lib/Parse/ParseExpr.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/test/SemaCXX/type-traits.cpp
clang/www/cxx_status.html
Index: clang/www/cxx_status.html
===================================================================
--- clang/www/cxx_status.html
+++ clang/www/cxx_status.html
@@ -1419,10 +1419,9 @@
<td><a href="https://wg21.link/P2255R2";>P2255R2</a></td>
<td class="partial" align="center">
<details><summary>Partial</summary>
- Clang provides a <tt>__reference_binds_to_temporary</tt> type trait
- builtin, with which the library facility can be partially implemented.
- Both <tt>__reference_constructs_from_temporary</tt> and
- <tt>__reference_converts_from_temporary</tt> builtins should be
+ Clang provides <tt>__reference_constructs_from_temporary</tt> type
+ trait builtin, with which <tt>std::reference_constructs_from_temporary</tt>
+ implemented. <tt>__reference_converts_from_temporary</tt> needs to be
provided, following the normal cross-vendor convention to implement
traits requiring compiler support directly.
</details></td>
Index: clang/test/SemaCXX/type-traits.cpp
===================================================================
--- clang/test/SemaCXX/type-traits.cpp
+++ clang/test/SemaCXX/type-traits.cpp
@@ -2535,6 +2535,55 @@
{ int arr[T((__reference_binds_to_temporary(const int &, long)))]; }
}
+void reference_constructs_from_temporary_checks() {
+ static_assert(!__reference_constructs_from_temporary(int &, int &), "");
+ static_assert(!__reference_constructs_from_temporary(int &, int &&), "");
+
+ static_assert(!__reference_constructs_from_temporary(int const &, int &), "");
+ static_assert(!__reference_constructs_from_temporary(int const &, int const &), "");
+ static_assert(!__reference_constructs_from_temporary(int const &, int &&), "");
+
+ static_assert(!__reference_constructs_from_temporary(int &, long &), ""); // doesn't construct
+
+ static_assert(__reference_constructs_from_temporary(int const &, long &), "");
+ static_assert(__reference_constructs_from_temporary(int const &, long &&), "");
+ static_assert(__reference_constructs_from_temporary(int &&, long &), "");
+
+ using LRef = ConvertsToRef<int, int &>;
+ using RRef = ConvertsToRef<int, int &&>;
+ using CLRef = ConvertsToRef<int, const int &>;
+ using LongRef = ConvertsToRef<long, long &>;
+ static_assert(__is_constructible(int &, LRef), "");
+ static_assert(!__reference_constructs_from_temporary(int &, LRef), "");
+
+ static_assert(__is_constructible(int &&, RRef), "");
+ static_assert(!__reference_constructs_from_temporary(int &&, RRef), "");
+
+ static_assert(__is_constructible(int const &, CLRef), "");
+ static_assert(!__reference_constructs_from_temporary(int &&, CLRef), "");
+
+ static_assert(__is_constructible(int const &, LongRef), "");
+ static_assert(__reference_constructs_from_temporary(int const &, LongRef), "");
+
+ // Test that it doesn't accept non-reference types as input.
+ static_assert(!__reference_constructs_from_temporary(int, long), "");
+
+ static_assert(__reference_constructs_from_temporary(const int &, long), "");
+
+ // Additional checks
+ static_assert(__reference_constructs_from_temporary(POD const&, Derives), "");
+ static_assert(__reference_constructs_from_temporary(int&&, int), "");
+ static_assert(__reference_constructs_from_temporary(const int&, int), "");
+ static_assert(!__reference_constructs_from_temporary(int&&, int&&), "");
+ static_assert(!__reference_constructs_from_temporary(const int&, int&&), "");
+ static_assert(__reference_constructs_from_temporary(int&&, long&&), "");
+ static_assert(__reference_constructs_from_temporary(int&&, long), "");
+}
+
+void reference_converts_from_temporary() {
+ (void)__reference_converts_from_temporary(int, int); // expected-error{{'__reference_converts_from_temporary' is a compiler-reserved identifier for a future feature}}
+}
+
void array_rank() {
int t01[T(__array_rank(IntAr) == 1)];
int t02[T(__array_rank(ConstIntArAr) == 2)];
Index: clang/lib/Sema/SemaExprCXX.cpp
===================================================================
--- clang/lib/Sema/SemaExprCXX.cpp
+++ clang/lib/Sema/SemaExprCXX.cpp
@@ -29,6 +29,7 @@
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/TokenKinds.h"
#include "clang/Basic/TypeTraits.h"
+#include "clang/Basic/TokenKinds.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/Initialization.h"
@@ -5325,14 +5326,15 @@
if (Kind <= UTT_Last)
return EvaluateUnaryTypeTrait(S, Kind, KWLoc, Args[0]->getType());
- // Evaluate BTT_ReferenceBindsToTemporary alongside the IsConstructible
- // traits to avoid duplication.
- if (Kind <= BTT_Last && Kind != BTT_ReferenceBindsToTemporary)
+ // Evaluate ReferenceBindsToTemporary and ReferenceConstructsFromTemporary
+ // alongside the IsConstructible traits to avoid duplication.
+ if (Kind <= BTT_Last && Kind != BTT_ReferenceBindsToTemporary && Kind != BTT_ReferenceConstructsFromTemporary)
return EvaluateBinaryTypeTrait(S, Kind, Args[0]->getType(),
Args[1]->getType(), RParenLoc);
switch (Kind) {
case clang::BTT_ReferenceBindsToTemporary:
+ case clang::BTT_ReferenceConstructsFromTemporary:
case clang::TT_IsConstructible:
case clang::TT_IsNothrowConstructible:
case clang::TT_IsTriviallyConstructible: {
@@ -5409,11 +5411,23 @@
if (Kind == clang::TT_IsConstructible)
return true;
- if (Kind == clang::BTT_ReferenceBindsToTemporary) {
+ if (Kind == clang::BTT_ReferenceBindsToTemporary || Kind == clang::BTT_ReferenceConstructsFromTemporary) {
if (!T->isReferenceType())
return false;
- return !Init.isDirectReferenceBinding();
+ if (!Init.isDirectReferenceBinding())
+ return true;
+
+ if (Kind == clang::BTT_ReferenceBindsToTemporary)
+ return false;
+
+ QualType U = Args[1]->getType();
+ if (U->isReferenceType())
+ return false;
+
+ QualType TPtr = S.BuiltinAddPointer(S.BuiltinRemoveReference(T, UnaryTransformType::RemoveCVRef, {}), {});
+ QualType UPtr = S.BuiltinAddPointer(S.BuiltinRemoveReference(U, UnaryTransformType::RemoveCVRef, {}), {});
+ return EvaluateBinaryTypeTrait(S, TypeTrait::BTT_IsConvertibleTo, UPtr, TPtr, RParenLoc);
}
if (Kind == clang::TT_IsNothrowConstructible)
@@ -5601,6 +5615,10 @@
QualType Rhs = Self.getASTContext().getUnqualifiedArrayType(RhsT, RhsQuals);
return Self.Context.typesAreCompatible(Lhs, Rhs);
}
+ case BTT_ReferenceConvertsFromTemporary: {
+ std::string Spelling = "'" + std::string(getTraitSpelling(BTT)) + "'";
+ return Self.Diag(KeyLoc, diag::err_reserved_identifier_for_future_use) << Spelling;
+ }
case BTT_IsConvertible:
case BTT_IsConvertibleTo: {
// C++0x [meta.rel]p4:
Index: clang/lib/Parse/ParseExpr.cpp
===================================================================
--- clang/lib/Parse/ParseExpr.cpp
+++ clang/lib/Parse/ParseExpr.cpp
@@ -1118,6 +1118,9 @@
REVERTIBLE_TYPE_TRAIT(__is_unsigned);
REVERTIBLE_TYPE_TRAIT(__is_void);
REVERTIBLE_TYPE_TRAIT(__is_volatile);
+ REVERTIBLE_TYPE_TRAIT(__reference_binds_to_temporary);
+ REVERTIBLE_TYPE_TRAIT(__reference_constructs_from_temporary);
+ REVERTIBLE_TYPE_TRAIT(__reference_converts_from_temporary);
#define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) \
REVERTIBLE_TYPE_TRAIT(RTT_JOIN(__, Trait));
#include "clang/Basic/TransformTypeTraits.def"
Index: clang/lib/Parse/ParseDeclCXX.cpp
===================================================================
--- clang/lib/Parse/ParseDeclCXX.cpp
+++ clang/lib/Parse/ParseDeclCXX.cpp
@@ -1628,7 +1628,10 @@
tok::kw___is_union,
tok::kw___is_unsigned,
tok::kw___is_void,
- tok::kw___is_volatile))
+ tok::kw___is_volatile,
+ tok::kw___reference_binds_to_temporary,
+ tok::kw___reference_constructs_from_temporary,
+ tok::kw___reference_converts_from_temporary))
// GNU libstdc++ 4.2 and libc++ use certain intrinsic names as the
// name of struct templates, but some are keywords in GCC >= 4.3
// and Clang. Therefore, when we see the token sequence "struct
Index: clang/lib/Lex/PPMacroExpansion.cpp
===================================================================
--- clang/lib/Lex/PPMacroExpansion.cpp
+++ clang/lib/Lex/PPMacroExpansion.cpp
@@ -1700,6 +1700,8 @@
.Case("__array_rank", true)
.Case("__array_extent", true)
.Case("__reference_binds_to_temporary", true)
+ .Case("__reference_constructs_from_temporary", true)
+ .Case("__reference_converts_from_temporary", true)
#define TRANSFORM_TYPE_TRAIT_DEF(_, Trait) .Case("__" #Trait, true)
#include "clang/Basic/TransformTypeTraits.def"
.Default(false);
Index: clang/include/clang/Basic/DiagnosticCommonKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticCommonKinds.td
+++ clang/include/clang/Basic/DiagnosticCommonKinds.td
@@ -392,4 +392,7 @@
"options %0 and %1 are set to different values">;
def err_opencl_feature_requires : Error<
"feature %0 requires support of %1 feature">;
+
+def err_reserved_identifier_for_future_use : Error<
+ "%0 is a compiler-reserved identifier for a future feature">;
}
Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -1474,6 +1474,7 @@
materialized temporary object. If ``T`` is not a reference type the result
is false. Note this trait will also return false when the initialization of
``T`` from ``U`` is ill-formed.
+* ``__reference_constructs_from_temporary(T, U)`` (C++)
* ``__underlying_type`` (C++, GNU, Microsoft)
In addition, the following expression traits are supported:
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