From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp88.iad3a.emailsrvr.com (smtp88.iad3a.emailsrvr.com [173.203.187.88]) by sourceware.org (Postfix) with ESMTPS id 3BFE338582AE for ; Thu, 4 Aug 2022 16:42:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 3BFE338582AE X-Auth-ID: tom@honermann.net Received: by smtp12.relay.iad3a.emailsrvr.com (Authenticated sender: tom-AT-honermann.net) with ESMTPSA id 6DF7624F97 for ; Thu, 4 Aug 2022 12:42:04 -0400 (EDT) Message-ID: <3d2d6940-b7b3-eac9-d2cf-1bd855128d8c@honermann.net> Date: Thu, 4 Aug 2022 12:42:03 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 1/1 v2] c++/106423: Fix pragma suppression of -Wc++20-compat diagnostics. Content-Language: en-US To: gcc-patches@gcc.gnu.org References: <20220724043902.1777378-2-tom@honermann.net> <20220801184900.1326396-1-tom@honermann.net> From: Tom Honermann In-Reply-To: <20220801184900.1326396-1-tom@honermann.net> X-Classification-ID: 85a2237d-420b-4a56-a49a-b9bb9f5093dc-1-1 X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, HTML_MESSAGE, KAM_SHORT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Aug 2022 16:42:10 -0000 Are there any further concerns with this patch? If not, I extend my gratitude to anyone so kind as to commit this for me as I don't have commit access. I just noticed that I neglected to add a ChangeLog entry for the comment addition to gcc/cp/parser.cc. Noted inline below. I can re-send the patch with that update if desired. Tom. On 8/1/22 2:49 PM, Tom Honermann wrote: > Gcc's '#pragma GCC diagnostic' directives are processed in "early mode" > (see handle_pragma_diagnostic_early) for the C++ frontend and, as such, > require that the target diagnostic option be enabled for the preprocessor > (see c_option_is_from_cpp_diagnostics). This change modifies the > -Wc++20-compat option definition to register it as a preprocessor option > so that its associated diagnostics can be suppressed. The changes also > implicitly disable the option in C++20 and later modes. These changes > are consistent with the definition of the -Wc++11-compat option. > > This support is motivated by the need to suppress the following diagnostic > otherwise issued in C++17 and earlier modes due to the char8_t typedef > present in the uchar.h header file in glibc 2.36. > warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat] > > Tests are added to validate suppression of both -Wc++11-compat and > -Wc++20-compat related diagnostics (fixes were only needed for the C++20 > case). > > Fixeshttps://gcc.gnu.org/PR106423. > > gcc/c-family/ChangeLog: > * c-opts.cc (c_common_post_options): Disable -Wc++20-compat diagnostics > in C++20 and later. > * c.opt (Wc++20-compat): Enable hooks for the preprocessor. gcc/cp/ChangeLog:     * parser.cc (cp_lexer_saving_tokens): Add comment regarding diagnostic requirements. > > gcc/testsuite/ChangeLog: > * g++.dg/cpp0x/keywords2.C: New test. > * g++.dg/cpp2a/keywords2.C: New test. > > libcpp/ChangeLog: > * include/cpplib.h (cpp_warning_reason): Add CPP_W_CXX20_COMPAT. > * init.cc (cpp_create_reader): Add cpp_warn_cxx20_compat. > --- > gcc/c-family/c-opts.cc | 7 +++++++ > gcc/c-family/c.opt | 2 +- > gcc/cp/parser.cc | 5 ++++- > gcc/testsuite/g++.dg/cpp0x/keywords2.C | 16 ++++++++++++++++ > gcc/testsuite/g++.dg/cpp2a/keywords2.C | 13 +++++++++++++ > libcpp/include/cpplib.h | 4 ++++ > libcpp/init.cc | 1 + > 7 files changed, 46 insertions(+), 2 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp0x/keywords2.C > create mode 100644 gcc/testsuite/g++.dg/cpp2a/keywords2.C > > diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc > index b9f01a65ed7..1ea37ba9742 100644 > --- a/gcc/c-family/c-opts.cc > +++ b/gcc/c-family/c-opts.cc > @@ -1046,6 +1046,13 @@ c_common_post_options (const char **pfilename) > else if (warn_narrowing == -1) > warn_narrowing = 0; > > + if (cxx_dialect >= cxx20) > + { > + /* Don't warn about C++20 compatibility changes in C++20 or later. */ > + warn_cxx20_compat = 0; > + cpp_opts->cpp_warn_cxx20_compat = 0; > + } > + > /* C++17 has stricter evaluation order requirements; let's use some of them > for earlier C++ as well, so chaining works as expected. */ > if (c_dialect_cxx () > diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt > index 44e1a60ce24..dfdebd596ef 100644 > --- a/gcc/c-family/c.opt > +++ b/gcc/c-family/c.opt > @@ -455,7 +455,7 @@ Wc++2a-compat > C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented > > Wc++20-compat > -C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) > +C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT) > Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020. > > Wc++11-extensions > diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc > index 4f67441eeb1..c3584446827 100644 > --- a/gcc/cp/parser.cc > +++ b/gcc/cp/parser.cc > @@ -924,7 +924,10 @@ cp_lexer_saving_tokens (const cp_lexer* lexer) > /* Store the next token from the preprocessor in *TOKEN. Return true > if we reach EOF. If LEXER is NULL, assume we are handling an > initial #pragma pch_preprocess, and thus want the lexer to return > - processed strings. */ > + processed strings. > + > + Diagnostics issued from this function must have their controlling option (if > + any) in c.opt annotated as a libcpp option via the CppReason property. */ > > static void > cp_lexer_get_preprocessor_token (unsigned flags, cp_token *token) > diff --git a/gcc/testsuite/g++.dg/cpp0x/keywords2.C b/gcc/testsuite/g++.dg/cpp0x/keywords2.C > new file mode 100644 > index 00000000000..d67d01e31ed > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp0x/keywords2.C > @@ -0,0 +1,16 @@ > +// { dg-do compile { target c++98_only } } > +// { dg-options "-Wc++11-compat" } > + > +// Validate suppression of -Wc++11-compat diagnostics. > +#pragma GCC diagnostic ignored "-Wc++11-compat" > +int alignof; > +int alignas; > +int constexpr; > +int decltype; > +int noexcept; > +int nullptr; > +int static_assert; > +int thread_local; > +int _Alignas; > +int _Alignof; > +int _Thread_local; > diff --git a/gcc/testsuite/g++.dg/cpp2a/keywords2.C b/gcc/testsuite/g++.dg/cpp2a/keywords2.C > new file mode 100644 > index 00000000000..8714a7b26b7 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/keywords2.C > @@ -0,0 +1,13 @@ > +// { dg-do compile { target c++17_down } } > +// { dg-options "-Wc++20-compat" } > + > +// Validate suppression of -Wc++20-compat diagnostics. > +#pragma GCC diagnostic ignored "-Wc++20-compat" > +int constinit; > +int consteval; > +int requires; > +int concept; > +int co_await; > +int co_yield; > +int co_return; > +int char8_t; > diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h > index 3eba6f74b57..9d90c18e4f2 100644 > --- a/libcpp/include/cpplib.h > +++ b/libcpp/include/cpplib.h > @@ -547,6 +547,9 @@ struct cpp_options > /* True if warn about differences between C++98 and C++11. */ > bool cpp_warn_cxx11_compat; > > + /* True if warn about differences between C++17 and C++20. */ > + bool cpp_warn_cxx20_compat; > + > /* Nonzero if bidirectional control characters checking is on. See enum > cpp_bidirectional_level. */ > unsigned char cpp_warn_bidirectional; > @@ -655,6 +658,7 @@ enum cpp_warning_reason { > CPP_W_C90_C99_COMPAT, > CPP_W_C11_C2X_COMPAT, > CPP_W_CXX11_COMPAT, > + CPP_W_CXX20_COMPAT, > CPP_W_EXPANSION_TO_DEFINED, > CPP_W_BIDIRECTIONAL > }; > diff --git a/libcpp/init.cc b/libcpp/init.cc > index f4ab83d2145..cca3c1dc1e7 100644 > --- a/libcpp/init.cc > +++ b/libcpp/init.cc > @@ -202,6 +202,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table, > CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1; > CPP_OPTION (pfile, cpp_warn_c11_c2x_compat) = -1; > CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0; > + CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0; > CPP_OPTION (pfile, cpp_warn_deprecated) = 1; > CPP_OPTION (pfile, cpp_warn_long_long) = 0; > CPP_OPTION (pfile, dollars_in_ident) = 1;