https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86875
Bug ID: 86875 Summary: internal compiler error: in tsubst_copy, at cp/pt.c:15478 Product: gcc Version: 8.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: ldalessandro at gmail dot com Target Milestone: --- ICE in 8.2 (Debian gcc package) when capturing `const` variable in y_combinator recursive lambda. This code works fine in 7.x. Capturing by reference or copy makes no difference. Removing `const` suppresses the ICE. Attached reduced test.ii test case. * g++ -std=c++14 -c -o test.o test.ii * Linux ****** 4.16.0-2-amd64 #1 SMP Debian 4.16.16-2 (2018-06-22) x86_64 GNU/Linux * gcc version 8.2.0 (Debian 8.2.0-1) * Configured with: ../src/configure -v --with-pkgversion='Debian 8.2.0-1' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-8 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --------------------------------- # Terminal session with details # --------------------------------- $ uname -a Linux ****** 4.16.0-2-amd64 #1 SMP Debian 4.16.16-2 (2018-06-22) x86_64 GNU/Linux $ gcc --version gcc (Debian 8.2.0-1) 8.2.0 Copyright (C) 2018 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ cat test.cpp #include <functional> // Adapted from http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0200r0.html. template<class Fun> class y_combinator_result { Fun fun_; public: template<class T> explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {} template<class ...Args> decltype(auto) operator()(Args &&...args) { return fun_(std::ref(*this), std::forward<Args>(args)...); } }; template<class Fun> decltype(auto) y_combinator(Fun &&fun) { return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun)); } int main() { const unsigned w = 1; // non-const works fine auto foo = y_combinator([=](auto foo) -> void { auto i = 0 + w; foo(); }); foo(); return 0; } $ g++ -v -std=c++14 -save-temps -c -o test.o test.cpp Using built-in specs. COLLECT_GCC=g++ OFFLOAD_TARGET_NAMES=nvptx-none OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Debian 8.2.0-1' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-8 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie --with-system-zlib --with-target-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 8.2.0 (Debian 8.2.0-1) COLLECT_GCC_OPTIONS='-v' '-std=c++14' '-save-temps' '-c' '-o' 'test.o' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/8/cc1plus -E -quiet -v -imultiarch x86_64-linux-gnu -D_GNU_SOURCE test.cpp -mtune=generic -march=x86-64 -std=c++14 -fpch-preprocess -o test.ii ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/8" ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/local/include" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/8/../../../../x86_64-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /opt/intel/compilers_and_libraries_2018.1.163/linux/mkl/include /usr/include/c++/8 /usr/include/x86_64-linux-gnu/c++/8 /usr/include/c++/8/backward /usr/lib/gcc/x86_64-linux-gnu/8/include /usr/lib/gcc/x86_64-linux-gnu/8/include-fixed /usr/include/x86_64-linux-gnu /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-std=c++14' '-save-temps' '-c' '-o' 'test.o' '-shared-libgcc' '-mtune=generic' '-march=x86-64' /usr/lib/gcc/x86_64-linux-gnu/8/cc1plus -fpreprocessed test.ii -quiet -dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase-strip test.o -std=c++14 -version -o test.s GNU C++14 (Debian 8.2.0-1) version 8.2.0 (x86_64-linux-gnu) compiled by GNU C version 8.2.0, GMP version 6.1.2, MPFR version 4.0.1, MPC version 1.1.0, isl version isl-0.19-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU C++14 (Debian 8.2.0-1) version 8.2.0 (x86_64-linux-gnu) compiled by GNU C version 8.2.0, GMP version 6.1.2, MPFR version 4.0.1, MPC version 1.1.0, isl version isl-0.19-GMP GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: 8ef452a0a06f9d64060be385354ae1d5 test.cpp: In instantiation of ‘main()::<lambda(auto:1)> [with auto:1 = std::reference_wrapper<y_combinator_result<main()::<lambda(auto:1)> > >]’: test.cpp:13:61: required from ‘decltype(auto) y_combinator_result<Fun>::operator()(Args&& ...) [with Args = {}; Fun = main()::<lambda(auto:1)>]’ test.cpp:28:7: required from here test.cpp:25:18: internal compiler error: in tsubst_copy, at cp/pt.c:15478 auto i = 0 + w; ~~^~~ Please submit a full bug report, with preprocessed source if appropriate. See <file:///usr/share/doc/gcc-8/README.Bugs> for instructions. make: *** [<builtin>: test.o] Error 1 $ apt show gcc Package: gcc Version: 4:8.1.0-1 Priority: optional Build-Essential: yes Section: devel Source: gcc-defaults (1.178) Maintainer: Debian GCC Maintainers <debian-...@lists.debian.org> Installed-Size: 46.1 kB Provides: c-compiler, gcc-x86-64-linux-gnu (= 4:8.1.0-1) Depends: cpp (= 4:8.1.0-1), gcc-8 (>= 8.1.0-4~) Recommends: libc6-dev | libc-dev Suggests: gcc-multilib, make, manpages-dev, autoconf, automake, libtool, flex, bison, gdb, gcc-doc Conflicts: gcc-doc (<< 1:2.95.3) Tag: devel::compiler, devel::lang:c, devel::library, implemented-in::c, interface::commandline, role::devel-lib, role::metapackage, role::program, suite::gnu, works-with::software:source Download-Size: 5,192 B APT-Manual-Installed: yes APT-Sources: http://mirrors.cat.pdx.edu/debian testing/main amd64 Packages Description: GNU C compiler This is the GNU C compiler, a fairly portable optimizing compiler for C. . This is a dependency package providing the default GNU C compiler.