On 12/02/21 12:31 +0100, Mirko Vogt wrote:
On 2/12/21 11:30 AM, Jonathan Wakely wrote:
This patch is wrong.
Indeed, thanks for checking.
If you simply disable that function definition
for !__cpp_rtti then you'll get linker errors from fstream.tcc when
that function is called.
/usr/bin/ld:
/home/jwakely/src/gcc/build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs/libstdc++.so:
undefined reference to `std::__throw_ios_failure(char const*, int)'
Funny enough that doesn't occur for my use case - builds fine. However
building with a toolchain for bare metal, potentially resulting in
disabling e.g. fstream.
This was done correctly for the c++98 part and probably just forgotten
for c++11.
This has nothing to do with C++98, it's relted to the gcc4-compatible
ABI versus the cxx11 ABI.
Urgs, yeah, that last chunk for cxx98 expands a different macro to
include that definition - not the rtti ifdef. Misread and wrongly took
over.
I added a better patch to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99077
I've committed that patch to master now (and will backport it to
gcc-10 and gcc-9 soon). Thanks for finding the bug.
commit 4591f7e5329dcc6ee9af2f314a050936d470ab5b
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Feb 12 10:37:56 2021
libstdc++: Fix bootstrap with -fno-rtti [PR 99077]
When libstdc++ is built without RTTI the __ios_failure type is just an
alias for std::ios_failure, so trying to construct it from an int won't
compile. This changes the RTTI-enabled __ios_failure type to have the
same constructor parameters as std::ios_failure, so that the constructor
takes the same arguments whether RTTI is enabled or not.
The __throw_ios_failure function now constructs the error_code, instead
of the __ios_failure constructor. As a drive-by fix that error_code is
constructed with std::generic_category() not std::system_category(),
because the int comes from errno which corresponds to the generic
category.
libstdc++-v3/ChangeLog:
PR libstdc++/99077
* src/c++11/cxx11-ios_failure.cc (__ios_failure(const char*, int)):
Change int parameter to error_code, to match std::ios_failure.
(__throw_ios_failure(const char*, int)): Construct error_code
from int parameter.
diff --git a/libstdc++-v3/src/c++11/cxx11-ios_failure.cc b/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
index e82c1aaf63b..a918ab21015 100644
--- a/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
+++ b/libstdc++-v3/src/c++11/cxx11-ios_failure.cc
@@ -114,7 +114,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__ios_failure(const char* s) : failure(s)
{ __construct_ios_failure(buf, runtime_error::what()); }
- __ios_failure(const char* s, int e) : failure(s, to_error_code(e))
+ __ios_failure(const char* s, const error_code& e) : failure(s, e)
{ __construct_ios_failure(buf, runtime_error::what()); }
~__ios_failure()
@@ -125,10 +125,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// There are assertions in src/c++98/ios_failure.cc to ensure the size
// and alignment assumptions are valid.
alignas(runtime_error) unsigned char buf[sizeof(runtime_error)];
-
- static error_code
- to_error_code(int e)
- { return e ? error_code(e, system_category()) : io_errc::stream; }
};
// Custom type info for __ios_failure.
@@ -171,7 +167,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void
__throw_ios_failure(const char* str __attribute__((unused)),
int err __attribute__((unused)))
- { _GLIBCXX_THROW_OR_ABORT(__ios_failure(_(str), err)); }
+ {
+ _GLIBCXX_THROW_OR_ABORT(__ios_failure(_(str),
+ err ? error_code(err, generic_category()) : io_errc::stream));
+ }
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
