From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp100.iad3a.emailsrvr.com (smtp100.iad3a.emailsrvr.com [173.203.187.100]) by sourceware.org (Postfix) with ESMTPS id B62CB3858283 for ; Thu, 11 Aug 2022 22:45:03 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B62CB3858283 X-Auth-ID: tom@honermann.net Received: by smtp29.relay.iad3a.emailsrvr.com (Authenticated sender: tom-AT-honermann.net) with ESMTPSA id 90E9223A48 for ; Thu, 11 Aug 2022 18:45:01 -0400 (EDT) Message-ID: Date: Thu, 11 Aug 2022 18:44:56 -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> <3d2d6940-b7b3-eac9-d2cf-1bd855128d8c@honermann.net> From: Tom Honermann In-Reply-To: <3d2d6940-b7b3-eac9-d2cf-1bd855128d8c@honermann.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Classification-ID: 15ff8c92-b489-47f5-9d59-000ff6b7e7ea-1-1 X-Spam-Status: No, score=-9.1 required=5.0 tests=BAYES_00, BODY_8BITS, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org 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, 11 Aug 2022 22:45:06 -0000 If there are no further concerns, could a C++ or libcpp maintainer please commit this for me? Thank you! Tom. On 8/4/22 12:42 PM, Tom Honermann via Gcc-patches wrote: > 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;