Created attachment 47807 [details] Assembler Consider the following example (a simplification of a real case): $ cat test.cpp void* callback(const char* name); extern "C" { inline void f1() { static void (*f)(); f = (void(*)()) callback("f1"); f(); } inline void f2() { static void (*f)(); f = (void(*)()) callback("f2"); f(); } } // extern "C" int main() { f1(); f2(); } $ g++ -save-temps test.cpp g++ -save-temps test.cpp test.s: Assembler messages: test.s:41: Error: symbol `f' is already defined As you can see in the attached test.s, symbol "f" for functions f1 and f2 is not mangled, and thus collides. Previous versions of GCC produce mangled identifiers _ZZ2f1E1f and _ZZ2f2E1f. $ g++ -v Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-redhat-linux Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --enable-offload-targets=nvptx-none --without-cuda-driver --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix Supported LTO compression algorithms: zlib gcc version 10.0.1 20200130 (Red Hat 10.0.1-0.7) (GCC)
Started with r10-6110-g8158a4640819dbb3210326e37786fb874f450272 , before that the vars have been mangled - _ZZ2f1E1f, _ZZ2f2E1f . BTW, I get an ICE instead of assembler-failure: pr93643.C:25:1: error: Two symbols with same comdat_group are not linked by the same_comdat_group list. 25 | } | ^ f/2 (void (* f)()) @0x7f7f7a699200 Type: variable definition analyzed Visibility: no_reorder public weak comdat comdat_group:f one_only previous sharing asm name: 0 References: Referring: f2/3 (write)f2/3 (read) Availability: not-ready Varpool flags: f/0 (void (* f)()) @0x7f7f7a699180 Type: variable definition analyzed Visibility: no_reorder public weak comdat comdat_group:f one_only next sharing asm name: 2 References: Referring: f1/1 (write)f1/1 (read) Availability: not-ready Varpool flags: pr93643.C:25:1: internal compiler error: symtab_node::verify failed 0xe54eff symtab_node::verify_symtab_nodes() ../../gcc/symtab.c:1342 0xe7cf94 symtab_node::checking_verify_symtab_nodes() ../../gcc/cgraph.h:667 0xe7b065 symbol_table::compile() ../../gcc/cgraphunit.c:2720 0xe7b696 symbol_table::finalize_compilation_unit() ../../gcc/cgraphunit.c:2984 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. assembler-failure only if -fno-checking.
Created attachment 47811 [details] test.ii
I got no backtrace, just the output shown in my first comment, at least with the gcc version included in Fedora Rawhide. I've just attached the test.ii file too. With -v: $ g++ -v -save-temps test.cpp Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/10/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-redhat-linux Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,d,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --enable-offload-targets=nvptx-none --without-cuda-driver --enable-gnu-indirect-function --enable-cet --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix Supported LTO compression algorithms: zlib gcc version 10.0.1 20200130 (Red Hat 10.0.1-0.7) (GCC) COLLECT_GCC_OPTIONS='-v' '-save-temps' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/libexec/gcc/x86_64-redhat-linux/10/cc1plus -E -quiet -v -D_GNU_SOURCE test.cpp -mtune=generic -march=x86-64 -fpch-preprocess -o test.ii ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/include-fixed" ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/../../../../x86_64-redhat-linux/include" #include "..." search starts here: #include <...> search starts here: /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/x86_64-redhat-linux /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/backward /usr/lib/gcc/x86_64-redhat-linux/10/include /usr/local/include /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-save-temps' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/libexec/gcc/x86_64-redhat-linux/10/cc1plus -fpreprocessed test.ii -quiet -dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase test -version -o test.s GNU C++14 (GCC) version 10.0.1 20200130 (Red Hat 10.0.1-0.7) (x86_64-redhat-linux) compiled by GNU C version 10.0.1 20200130 (Red Hat 10.0.1-0.7), GMP version 6.1.2, MPFR version 4.0.2-p1, MPC version 1.1.0, isl version isl-0.16.1-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C++14 (GCC) version 10.0.1 20200130 (Red Hat 10.0.1-0.7) (x86_64-redhat-linux) compiled by GNU C version 10.0.1 20200130 (Red Hat 10.0.1-0.7), GMP version 6.1.2, MPFR version 4.0.2-p1, MPC version 1.1.0, isl version isl-0.16.1-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 80355902cebbb142e87c9570dbf4f6a2 COLLECT_GCC_OPTIONS='-v' '-save-temps' '-shared-libgcc' '-mtune=generic' '-march=x86-64' as -v --64 -o test.o test.s GNU assembler version 2.34 (x86_64-redhat-linux) using BFD version version 2.34-1.fc32 test.s: Assembler messages: test.s:41: Error: symbol `f' is already defined
(In reply to Iñaki Ucar from comment #3) > I got no backtrace, just the output shown in my first comment, at least with > the gcc version included in Fedora Rawhide. I've just attached the test.ii > file too. With -v: Yes that is because the GCC is configured with "--enable-checking=release".
Fixed.
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>: https://gcc.gnu.org/g:abc79c6498a99e9c39e6056f432796c6dde3a887 commit r10-6628-gabc79c6498a99e9c39e6056f432796c6dde3a887 Author: Jason Merrill <jason@redhat.com> Date: Thu Feb 13 16:42:04 2020 +0100 c++: Fix static local vars in extern "C". Since my patch for PR 91476 moved visibility determination sooner, a local static in a vague linkage function now gets TREE_PUBLIC set before retrofit_lang_decl calls set_decl_linkage, which was making decl_linkage think that it has external linkage. It still has no linkage according to the standard. gcc/cp/ChangeLog 2020-02-13 Jason Merrill <jason@redhat.com> PR c++/93643 PR c++/91476 * tree.c (decl_linkage): Always lk_none for locals.