From 5030928d60a1d9ec71aed42038d5c74bce73845b Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Fri, 30 Aug 2019 22:52:55 +0000 Subject: [c++20] Implement semantic restrictions for C++20 designated initializers. This has some interesting interactions with our existing extensions to support C99 designated initializers as an extension in C++. Those are resolved as follows: * We continue to permit the full breadth of C99 designated initializers in C++, with the exception that we disallow a partial overwrite of an initializer with a non-trivially-destructible type. (Full overwrite is OK, because we won't run the first initializer at all.) * The C99 extensions are disallowed in SFINAE contexts and during overload resolution, where they could change the meaning of valid programs. * C++20 disallows reordering of initializers. We only check for that for the simple cases that the C++20 rules permit (designators of the form '.field_name =' and continue to allow reordering in other cases). It would be nice to improve this behavior in future. * All C99 designated initializer extensions produce a warning by default in C++20 mode. People are going to learn the C++ rules based on what Clang diagnoses, so it's important we diagnose these properly by default. * In C++ <= 17, we apply the C++20 rules rather than the C99 rules, and so still diagnose C99 extensions as described above. We continue to accept designated C++20-compatible initializers in C++ <= 17 silently by default (but naturally still reject under -pedantic-errors). This is not a complete implementation of P0329R4. In particular, that paper introduces new non-C99-compatible syntax { .field { init } }, and we do not support that yet. This is based on a previous patch by Don Hinton, though I've made substantial changes when addressing the above interactions. Differential Revision: https://reviews.llvm.org/D59754 llvm-svn: 370544 --- clang/test/Parser/cxx0x-lambda-expressions.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'clang/test/Parser/cxx0x-lambda-expressions.cpp') diff --git a/clang/test/Parser/cxx0x-lambda-expressions.cpp b/clang/test/Parser/cxx0x-lambda-expressions.cpp index 2acd8144b7a..d5091777842 100644 --- a/clang/test/Parser/cxx0x-lambda-expressions.cpp +++ b/clang/test/Parser/cxx0x-lambda-expressions.cpp @@ -1,5 +1,5 @@ -// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++11 %s -// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++2a %s +// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++11 -Wno-c99-designator %s +// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++2a -Wno-c99-designator %s enum E { e }; -- cgit v1.2.3