You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
73 lines
3.1 KiB
73 lines
3.1 KiB
From: Jonathan Wakely <jwakely@redhat.com>
|
|
Date: Fri, 7 Jan 2022 15:21:03 +0000 (+0000)
|
|
Subject: libstdc++: Add -nostdinc++ for c++17 sources [PR100017]
|
|
X-Git-Tag: releases/gcc-11.3.0~445
|
|
X-Git-Url: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff_plain;h=01a70ccd723eb9a479186fe37c972b0d0f8676cf
|
|
|
|
libstdc++: Add -nostdinc++ for c++17 sources [PR100017]
|
|
|
|
When building a build!=host compiler, the just-built gcc can't be used
|
|
to build the target libstdc++ (because it is built for the host triplet,
|
|
not the build triplet). The top-level configure.ac sets up the build
|
|
flags for libstdc++ (and other "raw_cxx" libs) like this:
|
|
|
|
GCC_TARGET_TOOL(c++ for libstdc++, RAW_CXX_FOR_TARGET, CXX,
|
|
[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],
|
|
c++)
|
|
|
|
The -nostdinc++ flag is only used for the IN-TREE-TOOL, i.e. when using
|
|
the just-built gcc/xgcc compiler. This means that the cross-compiler
|
|
used to build libstdc++ will add its own libstdc++ headers to the
|
|
include path. That results in the #include <cfenv> in
|
|
src/c++17/floating_to_chars.cc and src/c++17/floating_from_chars.cc
|
|
doing #include_next <fenv.h> and finding the libstdc++ fenv.h wrapper
|
|
from the host compiler. Because that has the same include guard as the
|
|
<fenv.h> in the libstdc++ we're trying to build, we never reach the
|
|
underlying <fenv.h> from libc. That results in several errors of the
|
|
form:
|
|
|
|
error: 'fenv_t' has not been declared in '::'
|
|
|
|
The most correct fix would be to add -nostdinc++ to the
|
|
RAW_CXX_FOR_TARGET variable in configure.ac, or the
|
|
RAW_CXX_TARGET_EXPORTS variable in Makefile.tpl.
|
|
|
|
Another solution would be to make the libstdc++ <fenv.h> wrapper use
|
|
_GLIBCXX_INCLUDE_NEXT_C_HEADERS like our <stdlib.h> and other C header
|
|
wrappers.
|
|
|
|
For now though, the simplest and safest solution is to just add
|
|
-nostdinc++ to the CXXFLAGS used for src/c++17/*.cc, which is what this
|
|
does.
|
|
|
|
libstdc++-v3/ChangeLog:
|
|
|
|
PR libstdc++/100017
|
|
* src/c++17/Makefile.am (AM_CXXFLAGS): Add -nostdinc++.
|
|
* src/c++17/Makefile.in: Regenerate.
|
|
|
|
(cherry picked from commit 4fde88e5dd152fe866a97b12e0f8229970d15cb3)
|
|
---
|
|
|
|
--- a/libstdc++-v3/src/c++17/Makefile.am
|
|
+++ b/libstdc++-v3/src/c++17/Makefile.am
|
|
@@ -79,7 +79,7 @@ endif
|
|
# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
|
|
# as the occasion calls for it.
|
|
AM_CXXFLAGS = \
|
|
- -std=gnu++17 \
|
|
+ -std=gnu++17 -nostdinc++ \
|
|
$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
|
|
$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
|
|
$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
|
|
--- a/libstdc++-v3/src/c++17/Makefile.in
|
|
+++ b/libstdc++-v3/src/c++17/Makefile.in
|
|
@@ -455,7 +455,7 @@ libc__17convenience_la_SOURCES = $(sourc
|
|
# OPTIMIZE_CXXFLAGS on the compile line so that -O2 can be overridden
|
|
# as the occasion calls for it.
|
|
AM_CXXFLAGS = \
|
|
- -std=gnu++17 \
|
|
+ -std=gnu++17 -nostdinc++ \
|
|
$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
|
|
$(XTEMPLATE_FLAGS) $(VTV_CXXFLAGS) \
|
|
$(WARN_CXXFLAGS) $(OPTIMIZE_CXXFLAGS) $(CONFIG_CXXFLAGS) \
|