https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99088
Bug ID: 99088
Summary: Failure to error on recursive template instantiation
in a reasonable time
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gabravier at gmail dot com
Target Milestone: ---
template<class T>struct W{T v;W(T v):v(v){}};
template<class T>int f(T x){f(W<T>(x));}
int main(){f(0);}
This seems to make GCC lag out for an *extremely* long time (at least long
enough that Godbolt kills GCC (20 seconds), I personally do not have a build of
trunk GCC to test this bug on). On GCC 10 and before, this resulted in an error
in a reasonable amount of time (<1 second)
-v output:
Using built-in specs.
COLLECT_GCC=/opt/compiler-explorer/gcc-snapshot/bin/g++
Target: x86_64-linux-gnu
Configured with: ../gcc-trunk-20210213/configure
--prefix=/opt/compiler-explorer/gcc-build/staging --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu --disable-bootstrap
--enable-multiarch --with-abi=m64 --with-multilib-list=m32,m64,mx32
--enable-multilib --enable-clocale=gnu --enable-languages=c,c++,fortran,ada,d
--enable-ld=yes --enable-gold=yes --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-linker-build-id --enable-lto
--enable-plugins --enable-threads=posix
--with-pkgversion=Compiler-Explorer-Build
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.0 20210212 (experimental) (Compiler-Explorer-Build)
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' './output.s'
'-masm=intel' '-S' '-O3' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
'-dumpdir' './'
/opt/compiler-explorer/gcc-trunk-20210213/bin/../libexec/gcc/x86_64-linux-gnu/11.0.0/cc1plus
-quiet -v -imultiarch x86_64-linux-gnu -iprefix
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/
-D_GNU_SOURCE <source> -quiet -dumpdir ./ -dumpbase output.cpp -dumpbase-ext
.cpp -masm=intel -mtune=generic -march=x86-64 -g -O3 -version
-fdiagnostics-color=always -o ./output.s
GNU C++17 (Compiler-Explorer-Build) version 11.0.0 20210212 (experimental)
(x86_64-linux-gnu)
compiled by GNU C version 7.5.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0/backward"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring duplicate directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/include-fixed"
ignoring nonexistent directory
"/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0/x86_64-linux-gnu
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../include/c++/11.0.0/backward
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/include
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/include-fixed
/usr/local/include
/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/../../include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++17 (Compiler-Explorer-Build) version 11.0.0 20210212 (experimental)
(x86_64-linux-gnu)
compiled by GNU C version 7.5.0, GMP version 6.1.0, MPFR version 3.1.4,
MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096
Compiler executable checksum: a47483d85f54b7b7df3d6a6237220aa1
COMPILER_PATH=/opt/compiler-explorer/gcc-trunk-20210213/bin/../libexec/gcc/x86_64-linux-gnu/11.0.0/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../libexec/gcc/x86_64-linux-gnu/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../libexec/gcc/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../x86_64-linux-gnu/bin/
LIBRARY_PATH=/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../lib64/:/lib/x86_64-linux-gnu/:/lib/../lib64/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib64/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../../x86_64-linux-gnu/lib/:/opt/compiler-explorer/gcc-trunk-20210213/bin/../lib/gcc/x86_64-linux-gnu/11.0.0/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-fdiagnostics-color=always' '-g' '-o' './output.s'
'-masm=intel' '-S' '-O3' '-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
'-dumpdir' './output.'
Godbolt link where I got the error: https://godbolt.org/z/16oh6e
