Author: Vlad Serebrennikov Date: 2024-02-21T19:02:20+04:00 New Revision: 73185854a3fc469b7d3e21d0b5d2ecb5ee15d201
URL: https://github.com/llvm/llvm-project/commit/73185854a3fc469b7d3e21d0b5d2ecb5ee15d201 DIFF: https://github.com/llvm/llvm-project/commit/73185854a3fc469b7d3e21d0b5d2ecb5ee15d201.diff LOG: [clang] Implement CWG1719 "Layout compatibility and cv-qualification revisited" (#82358) This patch updates our internal notion of `layout-compatible` to ignore cv-qualification, which in turn fixes `__is_layout_compatible` intrinsic. Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/SemaChecking.cpp clang/test/CXX/drs/dr17xx.cpp clang/test/SemaCXX/type-traits.cpp clang/www/cxx_dr_status.html Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index c17298bc7bce5e..15905e08955097 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -98,9 +98,8 @@ C++20 Feature Support - Implemented the `__is_layout_compatible` intrinsic to support `P0466R5: Layout-compatibility and Pointer-interconvertibility Traits <https://wg21.link/P0466R5>`_. - Note: `CWG1719: Layout compatibility and cv-qualification revisited <https://cplusplus.github.io/CWG/issues/1719.html>`_ - and `CWG2759: [[no_unique_address] and common initial sequence <https://cplusplus.github.io/CWG/issues/2759.html>`_ - are not yet implemented. + Note: `CWG2759: [[no_unique_address] and common initial sequence <https://cplusplus.github.io/CWG/issues/2759.html>`_ + is not yet implemented. C++23 Feature Support ^^^^^^^^^^^^^^^^^^^^^ @@ -120,6 +119,10 @@ Resolutions to C++ Defect Reports in the template parameters, but is deduced from a previous argument. (`#78449: <https://github.com/llvm/llvm-project/issues/78449>`_). +- Type qualifications are now ignored when evaluating layout compatibility + of two types. + (`CWG1719: Layout compatibility and cv-qualification revisited <https://cplusplus.github.io/CWG/issues/1719.html>`_). + C Language Changes ------------------ diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp index d951c0fc2732d2..e8bfb215a5b4c5 100644 --- a/clang/lib/Sema/SemaChecking.cpp +++ b/clang/lib/Sema/SemaChecking.cpp @@ -19124,15 +19124,16 @@ static bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) { if (T1.isNull() || T2.isNull()) return false; - // C++11 [basic.types] p11: - // If two types T1 and T2 are the same type, then T1 and T2 are - // layout-compatible types. - if (C.hasSameType(T1, T2)) - return true; - + // C++20 [basic.types] p11: + // Two types cv1 T1 and cv2 T2 are layout-compatible types + // if T1 and T2 are the same type, layout-compatible enumerations (9.7.1), + // or layout-compatible standard-layout class types (11.4). T1 = T1.getCanonicalType().getUnqualifiedType(); T2 = T2.getCanonicalType().getUnqualifiedType(); + if (C.hasSameType(T1, T2)) + return true; + const Type::TypeClass TC1 = T1->getTypeClass(); const Type::TypeClass TC2 = T2->getTypeClass(); diff --git a/clang/test/CXX/drs/dr17xx.cpp b/clang/test/CXX/drs/dr17xx.cpp index e5cee19337ebd4..d3cb5e58f06b32 100644 --- a/clang/test/CXX/drs/dr17xx.cpp +++ b/clang/test/CXX/drs/dr17xx.cpp @@ -46,7 +46,7 @@ namespace dr1715 { // dr1715: 3.9 #endif } -namespace dr1719 { // dr1719: no +namespace dr1719 { // dr1719: 19 #if __cplusplus >= 201103L struct CStruct { int one; @@ -66,11 +66,11 @@ struct CStructWithQualifiers { static_assert(__is_layout_compatible(CStruct, const CStruct2), ""); static_assert(__is_layout_compatible(CStruct, volatile CStruct2), ""); static_assert(__is_layout_compatible(const CStruct, volatile CStruct2), ""); -// FIXME: all of the following pairs of types are layout-compatible -static_assert(!__is_layout_compatible(int, const int), ""); -static_assert(!__is_layout_compatible(int, volatile int), ""); -static_assert(!__is_layout_compatible(const int, volatile int), ""); -static_assert(!__is_layout_compatible(CStruct, CStructWithQualifiers), ""); +static_assert(__is_layout_compatible(int, const int), ""); +static_assert(__is_layout_compatible(int, volatile int), ""); +static_assert(__is_layout_compatible(const int, volatile int), ""); +static_assert(__is_layout_compatible(CStruct, CStructWithQualifiers), ""); +static_assert(__is_layout_compatible(int[], const volatile int[]), ""); #endif } // namespace dr1719 diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp index 6ff04b6c8c7223..2c35d5ee19a4c6 100644 --- a/clang/test/SemaCXX/type-traits.cpp +++ b/clang/test/SemaCXX/type-traits.cpp @@ -1609,7 +1609,12 @@ struct CStructNoUniqueAddress2 { [[no_unique_address]] int two; }; -struct CStructAlignment { +struct alignas(64) CStructAlignment { + int one; + int two; +}; + +struct CStructAlignedMembers { int one; alignas(16) int two; }; @@ -1711,13 +1716,17 @@ void is_layout_compatible(int n) { static_assert(__is_layout_compatible(void, void), ""); static_assert(!__is_layout_compatible(void, int), ""); - static_assert(!__is_layout_compatible(void, const void), ""); // FIXME: this is CWG1719 - static_assert(!__is_layout_compatible(void, volatile void), ""); // FIXME: this is CWG1719 - static_assert(!__is_layout_compatible(const int, volatile int), ""); // FIXME: this is CWG1719 + static_assert(__is_layout_compatible(void, const void), ""); + static_assert(__is_layout_compatible(void, volatile void), ""); + static_assert(__is_layout_compatible(const int, volatile int), ""); static_assert(__is_layout_compatible(int, int), ""); - static_assert(!__is_layout_compatible(int, const int), ""); // FIXME: this is CWG1719 - static_assert(!__is_layout_compatible(int, volatile int), ""); // FIXME: this is CWG1719 - static_assert(!__is_layout_compatible(const int, volatile int), ""); // FIXME: this is CWG1719 + static_assert(__is_layout_compatible(int, const int), ""); + static_assert(__is_layout_compatible(int, volatile int), ""); + static_assert(__is_layout_compatible(const int, volatile int), ""); + static_assert(__is_layout_compatible(int *, int * __restrict), ""); + // Note: atomic qualification matters for layout compatibility. + static_assert(!__is_layout_compatible(int, _Atomic int), ""); + static_assert(__is_layout_compatible(_Atomic(int), _Atomic int), ""); static_assert(!__is_layout_compatible(int, unsigned int), ""); static_assert(!__is_layout_compatible(char, unsigned char), ""); static_assert(!__is_layout_compatible(char, signed char), ""); @@ -1758,10 +1767,11 @@ void is_layout_compatible(int n) static_assert(!__is_layout_compatible(CppStructNonStandardByVirtBase, CppStructNonStandardByVirtBase2), ""); static_assert(!__is_layout_compatible(CppStructNonStandardBySameBase, CppStructNonStandardBySameBase2), ""); static_assert(!__is_layout_compatible(CppStructNonStandardBy2ndVirtBase, CppStructNonStandardBy2ndVirtBase2), ""); - static_assert(!__is_layout_compatible(CStruct, CStructWithQualifiers), ""); // FIXME: this is CWG1719 + static_assert(__is_layout_compatible(CStruct, CStructWithQualifiers), ""); static_assert(__is_layout_compatible(CStruct, CStructNoUniqueAddress) == bool(__has_cpp_attribute(no_unique_address)), ""); // FIXME: this is CWG2759 static_assert(__is_layout_compatible(CStructNoUniqueAddress, CStructNoUniqueAddress2) == bool(__has_cpp_attribute(no_unique_address)), ""); // FIXME: this is CWG2759 static_assert(__is_layout_compatible(CStruct, CStructAlignment), ""); + static_assert(__is_layout_compatible(CStruct, CStructAlignedMembers), ""); // FIXME: alignment of members impact common initial sequence static_assert(__is_layout_compatible(CStructWithBitfelds, CStructWithBitfelds), ""); static_assert(__is_layout_compatible(CStructWithBitfelds, CStructWithBitfelds2), ""); static_assert(!__is_layout_compatible(CStructWithBitfelds, CStructWithBitfelds3), ""); diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html index e9b18b1e283e66..38e2cb63142662 100755 --- a/clang/www/cxx_dr_status.html +++ b/clang/www/cxx_dr_status.html @@ -7812,7 +7812,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td><a href="https://cplusplus.github.io/CWG/issues/1334.html";>1334</a></td> <td>NAD</td> <td>Layout compatibility and cv-qualification</td> - <td class="unknown" align="center">Unknown</td> + <td class="unreleased" align="center">Superseded by <a href="#1719">1719</a></td> </tr> <tr id="1335"> <td><a href="https://cplusplus.github.io/CWG/issues/1335.html";>1335</a></td> @@ -10122,7 +10122,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2> <td><a href="https://cplusplus.github.io/CWG/issues/1719.html";>1719</a></td> <td>CD4</td> <td>Layout compatibility and cv-qualification revisited</td> - <td class="unknown" align="center">Unknown</td> + <td class="unreleased" align="center">Clang 19</td> </tr> <tr id="1720"> <td><a href="https://cplusplus.github.io/CWG/issues/1720.html";>1720</a></td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
