From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qv1-xf29.google.com (mail-qv1-xf29.google.com [IPv6:2607:f8b0:4864:20::f29]) by sourceware.org (Postfix) with ESMTPS id 1AE93383D83B for ; Tue, 21 Jun 2022 07:38:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1AE93383D83B Received: by mail-qv1-xf29.google.com with SMTP id y14so13861843qvs.10 for ; Tue, 21 Jun 2022 00:38:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7oODxQqb/4Zl2VvY0kWjemS5hCFlTZ0DEZ8eQTO/Kcc=; b=Um7LXgqmNVKk+PlqkN7HRUMbkjc11e5+FCZtAxIp8MJ+gzv7W4LQgWmy4FtvIjbDqj RC6Od3clxTmVuNmCpRQr71+VBFKwj3Pdcir/++IRqWBP+xEXiWwumQQp3HH/TGReGsW2 +bYFnNki+09rxkteJR5OI+DGnw2JU1Yx7kXg58GlxdDFJyKgoEH6OweAGcP0s2FUHwVI 2vnL8zJ0XyNZzQp0L3OaF24bhZQQmn0Eys8cW2fQd1w+1oHYGXHoOheN592Vhln2swTZ Fvfl+o9k6BE0rauTGpNHX46hjNoDrZY5zBK1pQKOzPB2cjj08Bq3d5YEdiK9tmElxzEI 4GxQ== X-Gm-Message-State: AJIora9RI1htDgPh0B6lS2DjxkeEqYpt9zdtWWGwvbjiK5dpuvh8BIxv TRPMaEBkozS/okgulzlxpdXZERoOwqHwgUHpWwY= X-Google-Smtp-Source: AGRyM1tUB7inBwTxIa0+QFgzWLSWUqmu4zx96cap5M3vOsOvfYPtEOojKmd4JHQDUJBqxWwsKQhb8sWQrDmA13TyzX0= X-Received: by 2002:a05:6214:2129:b0:470:396d:19c4 with SMTP id r9-20020a056214212900b00470396d19c4mr10801519qvc.34.1655797081379; Tue, 21 Jun 2022 00:38:01 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Richard Biener Date: Tue, 21 Jun 2022 09:37:50 +0200 Message-ID: Subject: Re: [PATCH] Introduce -nolibstdc++ option To: Alexandre Oliva Cc: GCC Patches , Joseph Myers , Nathan Sidwell Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, 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: Tue, 21 Jun 2022 07:38:03 -0000 On Tue, Jun 21, 2022 at 7:56 AM Alexandre Oliva via Gcc-patches wrote: > > > Using g++ to link without libstdc++, as in g++.dg/abi/pure-virtual1.C, > is error prone, because there's no way to tell g++ to drop libstdc++ > without also dropping libc and any other libraries that the target > implicitly links in. > > This has often led to the need for manual adjustments to this > testcase. > > I figured adding support for -nolibstdc++, even though redundant, > makes some sense. One could presumably use gcc rather than g++ for > linking, for the same effect, but sometimes changing the link command > is harder than adding an option, as in our testsuite. > > Regstrapped on x86_64-linux-gnu, also tested with a cross to > aarch64-rtems6. Ok to install? OK in case nobody objects in 24h. Richard. > > for gcc/ChangeLog > > * common.opt (nolibstdc++): New. > * doc/invoke.texi (-nolibstdc++): Document it. > > for gcc/cp/ChangeLog > > * g++spec.c (lang_specific_driver): Implement -nolibstdc++. > > for gcc/testsuite/ChangeLog > > * g++.dg/abi/pure-virtual1.C: Use -nolibstdc++. > --- > gcc/common.opt | 3 +++ > gcc/cp/g++spec.cc | 1 + > gcc/doc/invoke.texi | 6 +++++- > gcc/testsuite/g++.dg/abi/pure-virtual1.C | 2 +- > 4 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/gcc/common.opt b/gcc/common.opt > index 32917aafcaec1..e00c6fc2fb098 100644 > --- a/gcc/common.opt > +++ b/gcc/common.opt > @@ -3456,6 +3456,9 @@ Driver > nolibc > Driver > > +nolibstdc++ > +Driver > + > nostdlib > Driver > > diff --git a/gcc/cp/g++spec.cc b/gcc/cp/g++spec.cc > index 8174d652776b1..539e6ca089d85 100644 > --- a/gcc/cp/g++spec.cc > +++ b/gcc/cp/g++spec.cc > @@ -160,6 +160,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options, > { > case OPT_nostdlib: > case OPT_nodefaultlibs: > + case OPT_nolibstdc__: > library = -1; > break; > > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index 50f57877477bc..469b6d97e0dfa 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -652,7 +652,7 @@ Objective-C and Objective-C++ Dialects}. > @item Linker Options > @xref{Link Options,,Options for Linking}. > @gccoptlist{@var{object-file-name} -fuse-ld=@var{linker} -l@var{library} @gol > --nostartfiles -nodefaultlibs -nolibc -nostdlib @gol > +-nostartfiles -nodefaultlibs -nolibc -nolibstdc++ -nostdlib @gol > -e @var{entry} --entry=@var{entry} @gol > -pie -pthread -r -rdynamic @gol > -s -static -static-pie -static-libgcc -static-libstdc++ @gol > @@ -16787,6 +16787,10 @@ absence of a C library is assumed, for example @option{-lpthread} or > @option{-lm} in some configurations. This is intended for bare-board > targets when there is indeed no C library available. > > +@item -nolibstdc++ > +@opindex nolibstdc++ > +Do not link with standard C++ libraries implicitly. > + > @item -nostdlib > @opindex nostdlib > Do not use the standard system startup files or libraries when linking. > diff --git a/gcc/testsuite/g++.dg/abi/pure-virtual1.C b/gcc/testsuite/g++.dg/abi/pure-virtual1.C > index 538e2cb097a0d..889c33e4952f4 100644 > --- a/gcc/testsuite/g++.dg/abi/pure-virtual1.C > +++ b/gcc/testsuite/g++.dg/abi/pure-virtual1.C > @@ -1,7 +1,7 @@ > // Test that we don't need libsupc++ just for __cxa_pure_virtual. > // { dg-do link } > // { dg-require-weak } > -// { dg-additional-options "-fno-rtti -nodefaultlibs -lc" } > +// { dg-additional-options "-fno-rtti -nolibstdc++" } > // { dg-additional-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } } > // { dg-xfail-if "AIX weak" { powerpc-ibm-aix* } } > > > -- > Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ > Free Software Activist GNU Toolchain Engineer > Disinformation flourishes because many people care deeply about injustice > but very few check the facts. Ask me about