Author: Aaron Ballman Date: 2023-02-23T07:41:35-05:00 New Revision: e328d68d5ba1fe365c36655b8ae287928da6d3ed
URL: https://github.com/llvm/llvm-project/commit/e328d68d5ba1fe365c36655b8ae287928da6d3ed DIFF: https://github.com/llvm/llvm-project/commit/e328d68d5ba1fe365c36655b8ae287928da6d3ed.diff LOG: [C++20] Stop claiming full support for consteval (for the moment!) During Clang 15, 3d2629dd3aab17098813c68b5b76bb864bc5e285 claimed we achieved full support for consteval in C++20. However, further testing shows that Clang doesn't correctly handle all of the examples from https://wg21.link/P1073R3 and has several other known issues that are preventing us from defining the `__cpp_consteval` macro. I think we should only claim Partial support for the moment. Once we correct the major outstanding issues, then I think we should change the status back to full support and define __cpp_consteval at the same time (even if it's only to the 201811L value instead of the latest value from C++2b). This helps users understand the support situation more clearly. Differential Revision: https://reviews.llvm.org/D144572 Added: clang/test/CXX/expr/expr.const/p8-2a.cpp Modified: clang/test/CXX/expr/expr.const/p6-2a.cpp clang/www/cxx_status.html Removed: ################################################################################ diff --git a/clang/test/CXX/expr/expr.const/p6-2a.cpp b/clang/test/CXX/expr/expr.const/p6-2a.cpp index 312c28354188d..2ef067c549003 100644 --- a/clang/test/CXX/expr/expr.const/p6-2a.cpp +++ b/clang/test/CXX/expr/expr.const/p6-2a.cpp @@ -41,3 +41,16 @@ struct Temporary { } }; constexpr Temporary t = {3}; // expected-error {{must have constant destruction}} expected-note {{created here}} expected-note {{in call}} + +namespace P1073R3 { +consteval int f() { return 42; } // expected-note 3 {{declared here}} +consteval auto g() { return f; } +// FIXME: there should be no diagnostics associated with either h() or r. +consteval int h(int (*p)() = g()) { return p(); } // expected-error {{call to consteval function 'P1073R3::g' is not a constant expression}} \ + expected-note {{declared here}} \ + expected-note {{pointer to a consteval declaration is not a constant expression}} +constexpr int r = h(); // expected-note {{in the default initalizer of 'p'}} +constexpr auto e = g(); // expected-error {{call to consteval function 'P1073R3::g' is not a constant expression}} \ + expected-error {{constexpr variable 'e' must be initialized by a constant expression}} \ + expected-note 2 {{pointer to a consteval declaration is not a constant expression}} +} // namespace P1073R3 diff --git a/clang/test/CXX/expr/expr.const/p8-2a.cpp b/clang/test/CXX/expr/expr.const/p8-2a.cpp new file mode 100644 index 0000000000000..b8bee64b0aae2 --- /dev/null +++ b/clang/test/CXX/expr/expr.const/p8-2a.cpp @@ -0,0 +1,22 @@ +// RUN: %clang_cc1 -std=c++20 -verify %s + +// expected-no-diagnostics + +namespace P1073R3 { +struct N { + constexpr N() {} + N(N const&) = delete; +}; + +template<typename T> constexpr void bad_assert_copyable() { T t; T t2 = t; } +using ineffective = decltype(bad_assert_copyable<N>()); + +// bad_assert_copyable<N> is not needed for constant evaluation +// (and thus not instantiated) +template<typename T> consteval void assert_copyable() { T t; T t2 = t; } +using check = decltype(assert_copyable<N>()); +// FIXME: this should give an error because assert_copyable<N> is instantiated +// (because it is needed for constant evaluation), but the attempt to copy t is +// ill-formed. +} // namespace P1073R3 + diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html index f93a788aa0d7a..c397b2ba25da1 100755 --- a/clang/www/cxx_status.html +++ b/clang/www/cxx_status.html @@ -1120,7 +1120,14 @@ <h2 id="cxx20">C++20 implementation status</h2> <tr> <td rowspan=2>Immediate functions (<tt>consteval</tt>)</td> <td><a href="https://wg21.link/p1073r3";>P1073R3</a></td> - <td class="full" align="center">Clang 15</td> + <td class="partial" align="center"> + <details><summary>Clang 15 (Partial)</summary> + Clang still incorrectly defers some consteval executions to runtime, + resulting in CodeGen crashes. Additionally, Clang does not properly + handle default arguments in consteval functions under all + circumstances. + </details> + </td> </tr> <tr> <!-- from Prague --> <td><a href="https://wg21.link/p1937r2";>P1937R2</a></td> _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
