ceaa6e840e
This is based on the toolchain GCC, and aims to share as much of its Makefile and patches with that definition. The package requires two additional patches: (1) 003-dont-choke-when-building-32bit-on-64bit.patch, which fixes the `error: size of array 'test_real_width' is negative` error that occurs when building a 32-bit GCC on a 64-bit host. (Search the Internet for examples of this error appearing.) (2) 980-add-nostdinc++.patch, which backports a fix from 11.3.0 (11.2.0 only). Signed-off-by: W. Michael Petullo <mike@flyn.org>
73 lines
3.1 KiB
Diff
73 lines
3.1 KiB
Diff
From: Jonathan Wakely <jwakely@redhat.com>
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Date: Fri, 7 Jan 2022 15:21:03 +0000 (+0000)
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Subject: libstdc++: Add -nostdinc++ for c++17 sources [PR100017]
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X-Git-Tag: releases/gcc-11.3.0~445
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X-Git-Url: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff_plain;h=01a70ccd723eb9a479186fe37c972b0d0f8676cf
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libstdc++: Add -nostdinc++ for c++17 sources [PR100017]
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When building a build!=host compiler, the just-built gcc can't be used
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to build the target libstdc++ (because it is built for the host triplet,
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not the build triplet). The top-level configure.ac sets up the build
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flags for libstdc++ (and other "raw_cxx" libs) like this:
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GCC_TARGET_TOOL(c++ for libstdc++, RAW_CXX_FOR_TARGET, CXX,
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[gcc/xgcc -shared-libgcc -B$$r/$(HOST_SUBDIR)/gcc -nostdinc++ -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/src/.libs -L$$r/$(TARGET_SUBDIR)/libstdc++-v3/libsupc++/.libs],
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c++)
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The -nostdinc++ flag is only used for the IN-TREE-TOOL, i.e. when using
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the just-built gcc/xgcc compiler. This means that the cross-compiler
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used to build libstdc++ will add its own libstdc++ headers to the
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include path. That results in the #include <cfenv> in
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src/c++17/floating_to_chars.cc and src/c++17/floating_from_chars.cc
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doing #include_next <fenv.h> and finding the libstdc++ fenv.h wrapper
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from the host compiler. Because that has the same include guard as the
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<fenv.h> in the libstdc++ we're trying to build, we never reach the
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underlying <fenv.h> from libc. That results in several errors of the
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form:
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error: 'fenv_t' has not been declared in '::'
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The most correct fix would be to add -nostdinc++ to the
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RAW_CXX_FOR_TARGET variable in configure.ac, or the
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RAW_CXX_TARGET_EXPORTS variable in Makefile.tpl.
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Another solution would be to make the libstdc++ <fenv.h> wrapper use
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_GLIBCXX_INCLUDE_NEXT_C_HEADERS like our <stdlib.h> and other C header
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wrappers.
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For now though, the simplest and safest solution is to just add
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-nostdinc++ to the CXXFLAGS used for src/c++17/*.cc, which is what this
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does.
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libstdc++-v3/ChangeLog:
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PR libstdc++/100017
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* src/c++17/Makefile.am (AM_CXXFLAGS): Add -nostdinc++.
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* src/c++17/Makefile.in: Regenerate.
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(cherry picked from commit 4fde88e5dd152fe866a97b12e0f8229970d15cb3)
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---
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--- a/libstdc++-v3/src/c++17/Makefile.am
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+++ b/libstdc++-v3/src/c++17/Makefile.am
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@@ -79,7 +79,7 @@ endif
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# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
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# as the occasion calls for it.
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AM_CXXFLAGS = \
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- -std=gnu++17 \
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+ -std=gnu++17 -nostdinc++ \
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$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
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$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
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$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
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--- a/libstdc++-v3/src/c++17/Makefile.in
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+++ b/libstdc++-v3/src/c++17/Makefile.in
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@@ -455,7 +455,7 @@ libc__17convenience_la_SOURCES = $(sourc
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# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
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# as the occasion calls for it.
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AM_CXXFLAGS = \
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- -std=gnu++17 \
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+ -std=gnu++17 -nostdinc++ \
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$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
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$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
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$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
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