From b457b779427b0f7b3fbac447811c9c52db5bc79e Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Tue, 8 Nov 2022 00:35:09 +0100 Subject: [PATCH] libstdc++: Fix up libstdc++ build against glibc 2.25 or older [PR107562] On Mon, Nov 07, 2022 at 05:48:42PM +0000, Jonathan Wakely wrote: > On Mon, 7 Nov 2022 at 16:11, Joseph Myers wrote: > > > > On Wed, 2 Nov 2022, Jakub Jelinek via Gcc-patches wrote: > > > > > APIs. So that one can build gcc against older glibc and then compile > > > user programs on newer glibc, the patch uses weak references unless > > > gcc is compiled against glibc 2.26+. strfromf128 unfortunately can't > > > > This support for older glibc doesn't actually seem to be working, on an > > older system with glibc 2.19 I'm seeing > > > > /scratch/jmyers/fsf/gcc-mainline/libstdc++-v3/src/c++17/floating_to_chars.cc:52:3: error: expected initializer before '__asm' > > 52 | __asm ("strfromf128"); > > | ^~~~~ > > > > and a series of subsequent errors. > > This seems to "fix" it (not sure if it's right though): > > #ifndef _GLIBCXX_HAVE_FLOAT128_MATH > extern "C" _Float128 __strtof128(const char*, char**) > __attribute__((__weak__)); > #endif > extern "C" _Float128 __strtof128(const char*, char**) > __asm ("strtof128"); It is, but floating_from_chars.cc has the same problem, and I think we can avoid the duplication, like this: 2022-11-08 Jakub Jelinek PR libstdc++/107562 * src/c++17/floating_from_chars.cc (__strtof128): Put __asm before __attribute__. * src/c++17/floating_to_chars.cc (__strfromf128): Likewise. --- libstdc++-v3/src/c++17/floating_from_chars.cc | 3 ++- libstdc++-v3/src/c++17/floating_to_chars.cc | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc index 11a9be6..29eb463 100644 --- a/libstdc++-v3/src/c++17/floating_from_chars.cc +++ b/libstdc++-v3/src/c++17/floating_from_chars.cc @@ -63,10 +63,11 @@ extern "C" __ieee128 __strtoieee128(const char*, char**); && defined(__GLIBC_PREREQ) #define USE_STRTOF128_FOR_FROM_CHARS 1 extern "C" _Float128 __strtof128(const char*, char**) + __asm ("strtof128") #ifndef _GLIBCXX_HAVE_FLOAT128_MATH __attribute__((__weak__)) #endif - __asm ("strtof128"); + ; #endif #if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ diff --git a/libstdc++-v3/src/c++17/floating_to_chars.cc b/libstdc++-v3/src/c++17/floating_to_chars.cc index d6be646..afce8d7 100644 --- a/libstdc++-v3/src/c++17/floating_to_chars.cc +++ b/libstdc++-v3/src/c++17/floating_to_chars.cc @@ -46,10 +46,11 @@ extern "C" int __sprintfieee128(char*, const char*, ...); #elif __FLT128_MANT_DIG__ == 113 && __LDBL_MANT_DIG__ != 113 \ && defined(__GLIBC_PREREQ) extern "C" int __strfromf128(char*, size_t, const char*, _Float128) + __asm ("strfromf128") #ifndef _GLIBCXX_HAVE_FLOAT128_MATH __attribute__((__weak__)) #endif - __asm ("strfromf128"); + ; #endif // This implementation crucially assumes float/double have the -- 2.7.4