https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81074
Bug ID: 81074
Summary: [7 regression] Nested template specialization causes
segmentation fault
Product: gcc
Version: 7.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jan at ypmania dot nl
Target Milestone: ---
Created attachment 41539
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41539&action=edit
Source file causing the segfault
The attached test.cpp defines a partially specialized template inside of a
template, i.e. as
template <typename T>
struct Outer {
template <typename F, typename G>
struct Inner {};
template <typename G>
struct Inner<int, G> { ... };
};
and causes a segmentation fault while trying to resolve constexpr's inside
Inner. The problem goes away if I flatten the structure, moving the inner
templates into the global namespace.
This is possibly related / duplicate of #55639; however, the code compiled fine
under GCC 6 and 5 (compiler explorer verifies this).
GCC Output: -------------------------------------------------------
$ gcc -v -save-temps test.cpp
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib
--libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=https://bugs.archlinux.org/
--enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-shared
--enable-threads=posix --enable-libmpx --with-system-zlib --with-isl
--enable-__cxa_atexit --disable-libunwind-exceptions --enable-clocale=gnu
--disable-libstdcxx-pch --disable-libssp --enable-gnu-unique-object
--enable-linker-build-id --enable-lto --enable-plugin
--enable-install-libiberty --with-linker-hash-style=gnu
--enable-gnu-indirect-function --disable-multilib --disable-werror
--enable-checking=release
Thread model: posix
gcc version 7.1.1 20170516 (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/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-pc-linux-gnu/7.1.1/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1/x86_64-pc-linux-gnu
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1/backward
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/include
/usr/local/include
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/include-fixed
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/cc1plus -fpreprocessed test.ii -quiet
-dumpbase test.cpp -mtune=generic -march=x86-64 -auxbase test -version -o
test.s
GNU C++14 (GCC) version 7.1.1 20170516 (x86_64-pc-linux-gnu)
compiled by GNU C version 7.1.1 20170516, GMP version 6.1.2, MPFR
version 3.1.5-p2, MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++14 (GCC) version 7.1.1 20170516 (x86_64-pc-linux-gnu)
compiled by GNU C version 7.1.1 20170516, GMP version 6.1.2, MPFR
version 3.1.5-p2, MPC version 1.0.3, isl version isl-0.18-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 74aace2f6deb87bb86dbfd7a28ebe524
test.cpp: In substitution of ‘template<unsigned char _fieldIdx, uint8_t Msg::*
field> struct Outer<Msg>::Varint<_fieldIdx, unsigned char, field> [with
unsigned char _fieldIdx = 1; uint8_t Msg::* field = &Msg::a]’:
test.cpp:5:30: required from ‘constexpr const uint8_t
HighestMaxFieldIdx<Outer<Msg>::Varint<1, unsigned char, &Msg::a>
>::maxFieldIdx’
test.cpp:25:95: required from here
test.cpp:5:30: internal compiler error: Segmentation fault
static constexpr uint8_t maxFieldIdx = T::fieldIdx;
^~~~~~~~~~~
