https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121935
Bug ID: 121935
Summary: [16 Regression] various LTO streamer ICEs since
g:b9fde0219f35cd5244f647c20c7b31b0395dbc5a
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: ice-on-valid-code
Severity: normal
Priority: P3
Component: lto
Assignee: unassigned at gcc dot gnu.org
Reporter: tnfchris at gcc dot gnu.org
CC: nshead at gcc dot gnu.org
Target Milestone: ---
Target: aarch64*
Since g:b9fde0219f35cd5244f647c20c7b31b0395dbc5a
>From b9fde0219f35cd5244f647c20c7b31b0395dbc5a Mon Sep 17 00:00:00 2001
From: Nathaniel Shead <nathanielosh...@gmail.com>
Date: Wed, 10 Sep 2025 14:25:22 +1000
Subject: [PATCH] ipa-free-lang-data: Don't walk into DECL_CHAIN when finding
decls/types [PR121865]
On a DECL, TREE_CHAIN will find any other declarations in the same
binding level. This caused an ICE in PR121865 because the next entity
in the binding level was the uninstantiated unique friend 'foo', for
which after being found the compiler tries to generate a mangled name
for it and crashes.
The following testcase
-- foo.ii
struct a {
static int b;
};
template <int> struct c {
struct d {
d e(unsigned, unsigned, bool, bool, bool, unsigned, a);
};
};
template <>
c<2>::d c<2>::d::e(unsigned, unsigned, bool, bool, bool, unsigned, const a) { }
compiled with g++ -S -o /dev/null -flto=auto -std=c++11
ICEs with
during IPA pass: modref
quadrature.ii: At top level:
quadrature.ii:10:79: internal compiler error: in streamer_write_chain, at
tree-streamer-out.cc:555
0x1f6f273 internal_error(char const*, ...)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/diagnostic-global-context.cc:786
0x8752b7 fancy_abort(char const*, int, char const*)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/diagnostics/context.cc:1786
0x12dc01b streamer_write_chain
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/tree-streamer-out.cc:555
0x12dc01b streamer_write_chain
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/tree-streamer-out.cc:547
0x12de88b write_ts_type_non_common_tree_pointers
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/tree-streamer-out.cc:763
0x12de88b streamer_write_tree_body(output_block*, tree_node*)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/tree-streamer-out.cc:970
0xf0aeb7 lto_write_tree_1
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:516
0xf11b6f DFS::DFS(output_block*, tree_node*, bool, bool, bool)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:922
0xf12b0b lto_output_tree(output_block*, tree_node*, bool, bool)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:1886
0xf0b09f write_global_stream
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:2968
0xf15a1f lto_output_decl_state_streams(output_block*, lto_out_decl_state*)
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:3015
0xf15a1f produce_asm_for_decls()
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/lto-streamer-out.cc:3427
0xf94a2f write_lto
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/passes.cc:2784
0xf94a2f ipa_write_summaries_1
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/passes.cc:2847
0xf94a2f ipa_write_summaries()
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/passes.cc:2902
0xbec817 ipa_passes
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/cgraphunit.cc:2276
0xbec817 symbol_table::compile()
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/cgraphunit.cc:2351
0xbee843 symbol_table::compile()
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/cgraphunit.cc:2329
0xbee843 symbol_table::finalize_compilation_unit()
/opt/buildAgent/work/5c94c4ced6ebfcd0/gcc/cgraphunit.cc:2608
