[PATCH] s390: Fix ABI issue in libstdc++.so.6

[Jakub Jelinek]

On Sat, Jan 10, 2026 at 05:24:15PM +0100, Stefan Schulze Frielinghaus wrote:
> libstdc++-v3/ChangeLog:
> 
>       * config/abi/post/s390x-linux-gnu/baseline_symbols.txt: Add
>       names {,P,K}DF16.

This is wrong - an ABI issue.

You can't export new symbols in CXXABI_1.3.14 symbol version when they
weren't exported there in GCC 13.1 already.
Symbols new in GCC 16 like these should be exported in CXXABI_1.3.17.

So, I think you want (completely untested):

2026-01-10  Jakub Jelinek  <ja...@redhat.com>

        * config/abi/pre/gnu.ver (CXXABI_1.3.14): Don't export _ZTI*DF16_ on
        s390x.
        (CXXABI_1.3.17): Export _ZTI*DF16_ on s390x.
        * config/abi/post/s390x-linux-gnu/baseline_symbols.txt: Remove
        _ZTI{,P,K}DF16_.

--- libstdc++-v3/config/abi/pre/gnu.ver.jj      2026-01-02 09:56:10.583329488 
+0100
+++ libstdc++-v3/config/abi/pre/gnu.ver 2026-01-10 18:58:37.133669626 +0100
@@ -2899,9 +2899,16 @@ CXXABI_1.3.14 {
 
     # typeinfo for _Float{16,32,64,128,32x,64x,128x} and
     # __bf16/bfloat16_t
+#ifndef __s390x__
     _ZTIDF[0-9]*[_x];
     _ZTIPDF[0-9]*[_x];
     _ZTIPKDF[0-9]*[_x];
+#else
+    # No _Float16 on s390x in GCC 13.
+    _ZTIDF[0-9]*[0-57-9][_x];
+    _ZTIPDF[0-9]*[0-57-9][_x];
+    _ZTIPKDF[0-9]*[0-57-9][_x];
+#endif
 #ifndef __riscv
     _ZTIDF16b;
     _ZTIPDF16b;
@@ -2933,6 +2940,13 @@ CXXABI_1.3.16 {
 CXXABI_1.3.17 {
     # std::exception_ptr::_M_exception_ptr_cast
     
_ZNKSt15__exception_ptr13exception_ptr21_M_exception_ptr_castERKSt9type_info;
+
+#ifdef __s390x__
+    _ZTIDF16_;
+    _ZTIPDF16_;
+    _ZTIPKDF16_;
+#endif
+
 #ifdef __riscv
 } CXXABI_1.3.16;
 #else
--- libstdc++-v3/config/abi/post/s390x-linux-gnu/baseline_symbols.txt.jj        
2026-01-10 18:52:48.533640534 +0100
+++ libstdc++-v3/config/abi/post/s390x-linux-gnu/baseline_symbols.txt   
2026-01-10 18:59:02.224239870 +0100
@@ -4951,7 +4951,6 @@ OBJECT:15:_ZTSSt8messagesIwE@@GLIBCXX_3.
 OBJECT:15:_ZTSSt8numpunctIcE@@GLIBCXX_3.4
 OBJECT:15:_ZTSSt8numpunctIwE@@GLIBCXX_3.4
 OBJECT:16:_ZTIDF128_@@CXXABI_1.3.14
-OBJECT:16:_ZTIDF16_@@CXXABI_1.3.14
 OBJECT:16:_ZTIDF32_@@CXXABI_1.3.14
 OBJECT:16:_ZTIDF32x@@CXXABI_1.3.14
 OBJECT:16:_ZTIDF64_@@CXXABI_1.3.14
@@ -5616,7 +5615,6 @@ OBJECT:30:_ZTSSt7codecvtIDsDu11__mbstate
 
OBJECT:32:_ZNSbIwSt11char_traitsIwESaIwEE4_Rep20_S_empty_rep_storageE@@GLIBCXX_3.4
 OBJECT:32:_ZNSs4_Rep20_S_empty_rep_storageE@@GLIBCXX_3.4
 OBJECT:32:_ZTIPDF128_@@CXXABI_1.3.14
-OBJECT:32:_ZTIPDF16_@@CXXABI_1.3.14
 OBJECT:32:_ZTIPDF32_@@CXXABI_1.3.14
 OBJECT:32:_ZTIPDF32x@@CXXABI_1.3.14
 OBJECT:32:_ZTIPDF64_@@CXXABI_1.3.14
@@ -5629,7 +5627,6 @@ OBJECT:32:_ZTIPDn@@CXXABI_1.3.5
 OBJECT:32:_ZTIPDs@@CXXABI_1.3.3
 OBJECT:32:_ZTIPDu@@CXXABI_1.3.12
 OBJECT:32:_ZTIPKDF128_@@CXXABI_1.3.14
-OBJECT:32:_ZTIPKDF16_@@CXXABI_1.3.14
 OBJECT:32:_ZTIPKDF32_@@CXXABI_1.3.14
 OBJECT:32:_ZTIPKDF32x@@CXXABI_1.3.14
 OBJECT:32:_ZTIPKDF64_@@CXXABI_1.3.14


        Jakub