https://github.com/AaronBallman created https://github.com/llvm/llvm-project/pull/166966
This paper allows use of * in a multidimensional array extent within a _Generic selection association, as a wildcard for any array extent. Clang does not currently support this feature, so this is just some initial test coverage along with an update to the conformance site. >From a9d6925010c59360efc3517717023f1240a0aae8 Mon Sep 17 00:00:00 2001 From: Aaron Ballman <[email protected]> Date: Fri, 7 Nov 2025 12:08:36 -0500 Subject: [PATCH] [C2y] Claim nonconformance to WG14 N3348 This paper allows use of * in a multidimensional array extent within a _Generic selection association, as a wildcard for any array extent. Clang does not currently support this feature, so this is just some initial test coverage along with an update to the conformance site. --- clang/test/C/C2y/n3348.c | 44 ++++++++++++++++++++++++++++++++++++++++ clang/www/c_status.html | 2 +- 2 files changed, 45 insertions(+), 1 deletion(-) create mode 100644 clang/test/C/C2y/n3348.c diff --git a/clang/test/C/C2y/n3348.c b/clang/test/C/C2y/n3348.c new file mode 100644 index 0000000000000..e20c9f74883f9 --- /dev/null +++ b/clang/test/C/C2y/n3348.c @@ -0,0 +1,44 @@ +// RUN: %clang_cc1 -verify -std=c2y -Wall -pedantic %s + +/* WG14 N3348: No + * Matching of Multi-Dimensional Arrays in Generic Selection Expressions + * + * This allows use of * in a _Generic association as a placeholder for any size + * value. + * + * FIXME: Clang doesn't yet implement this paper. When we do implement it, we + * should expose the functionality in earlier language modes (C89) for + * compatibility with GCC. + */ + +void test(int n, int m) { + static_assert(1 == _Generic(int[3][2], int[3][*]: 1, int[2][*]: 0)); /* expected-error {{star modifier used outside of function prototype}} + expected-error {{array has incomplete element type 'int[]'}} + */ + static_assert(1 == _Generic(int[3][2], int[*][2]: 1, int[*][3]: 0)); // expected-error {{star modifier used outside of function prototype}} + static_assert(1 == _Generic(int[3][n], int[3][*]: 1, int[2][*]: 0)); /* expected-error {{star modifier used outside of function prototype}} + expected-error {{array has incomplete element type 'int[]'}} + */ + static_assert(1 == _Generic(int[n][m], int[*][*]: 1, char[*][*]: 0)); /* expected-error 2 {{star modifier used outside of function prototype}} + expected-error {{array has incomplete element type 'int[]'}} + */ + static_assert(1 == _Generic(int(*)[2], int(*)[*]: 1)); // expected-error {{star modifier used outside of function prototype}} +} + +void questionable() { + // GCC accepts this despite the * appearing outside of a generic association, + // but it's not clear whether that's intentionally supported or an oversight. + // It gives a warning about * being used outside of a declaration, but not + // with an associated warning group. + static_assert(1 == _Generic(int[*][*], int[2][100]: 1)); /* expected-error 2 {{star modifier used outside of function prototype}} + expected-error {{array has incomplete element type 'int[]'}} + */ + // GCC claims this matches multiple associations, so the functionality seems + // like it may be intended to work? + (void)_Generic(int[*][*], /* expected-error 2 {{star modifier used outside of function prototype}} + expected-error {{array has incomplete element type 'int[]'}} + */ + int[2][100]: 1, + int[3][1000]: 2, + ); +} diff --git a/clang/www/c_status.html b/clang/www/c_status.html index 2c1f6f4140a91..ccf19ea86957a 100644 --- a/clang/www/c_status.html +++ b/clang/www/c_status.html @@ -324,7 +324,7 @@ <h2 id="c2y">C2y implementation status</h2> <tr> <td>Matching of Multi-Dimensional Arrays in Generic Selection Expressions</td> <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3348.pdf";>N3348</a></td> - <td class="unknown" align="center">Unknown</td> + <td class="none" align="center">No</td> </tr> <tr> <td>The __COUNTER__ predefined macro</td> _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
