https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104008
Bug ID: 104008
Summary: New g++ folly compile error with gcc 11.x. Bisected to
PR99445 c++: Alias template in pack expansion
Product: gcc
Version: 11.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ahornby at fb dot com
Target Milestone: ---
Created attachment 52178
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52178&action=edit
gzipped preprocessed source used for the bisect
When compiling folly on Fedora 35 with gcc from the included 11.2.1-7 package,
I found that the badge_test code fails to compile, whereas it builds fine with
gcc 10.x and with the fedora 35 clang (13.0.0-3.fc35)).
Bisecting from https://gcc.gnu.org/git/gcc.git with pre-processed source
indicates problem introduced in commit:
[a2531859bf5bf6cf1f29c0dca85fd26e80904a5d] c++: Alias template in pack
expansion [PR99445] (mirror at
https://github.com/gcc-mirror/gcc/commit/a2531859bf5bf6cf1f29c0dca85fd26e80904a5d)
I've also tested latest master and problem present there as well.
Bisected with commands, (bisection script below)
git bisect start basepoints/gcc-12 basepoints/gcc-11
git bisect run ~/local/bisect/gxx_bisect.sh
Example of the problem from a folly build along with the command line I got
preprocessed source from is in
https://github.com/facebook/folly/commit/af966d2ce25c14c96373bf39c8ae2b406219ffb4
Error looks like:
'/home/alex/local/bisect/test/0cc79337ad265aabccab63882a810f9dc509a9d0/build'
In file included from /home/alex/local/folly/folly/lang/test/BadgeTest.cpp:19:
/home/alex/local/folly/folly/lang/Badge.h: In instantiation of ‘class
folly::any_badge<{anonymous}::FriendClass, {anonymous}::OtherFriendClass>’:
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp:38:40: required from
here
/home/alex/local/folly/folly/lang/Badge.h:99:18: error: expansion pattern
‘folly::StrictDisjunction...>’ contains no
parameter packs
99 | /* implicit */ any_badge(any_badge) noexcept {}
| ^
/home/alex/local/folly/folly/lang/Badge.h: In instantiation of ‘class
folly::any_badge<{anonymous}::FriendClass, {anonymous}::OtherFriendClass,
{anonymous}::DummyClass>’:
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp:39:53: required from
here
/home/alex/local/folly/folly/lang/Badge.h:99:18: error: expansion pattern
‘folly::StrictDisjunction...>’ contains no
parameter packs
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp: In static member function
‘static void {anonymous}::ProtectedClass::subset({anonymous}::SubsetBadges)’:
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp:39:54: error: cannot
convert ‘any_badge<{anonymous}::FriendClass, {anonymous}::OtherFriendClass>’ to
‘any_badge<{anonymous}::FriendClass, {anonymous}::OtherFriendClass,
{anonymous}::DummyClass>’
39 | static void subset(SubsetBadges badges) { superset(badges); }
| ^~
| |
|
any_badge<{anonymous}::FriendClass, {anonymous}::OtherFriendClass>
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp:40:24: note:
initializing argument 1 of ‘static void
{anonymous}::ProtectedClass::superset({anonymous}::SupersetBadges)’
40 | static void superset(SupersetBadges) {}
|^~
In file included from /home/alex/local/folly/folly/lang/test/BadgeTest.cpp:19:
/home/alex/local/folly/folly/lang/Badge.h: In instantiation of ‘class
folly::any_badge<{anonymous}::FriendClass>’:
/home/alex/local/folly/folly/lang/test/BadgeTest.cpp:47:35: required from
here
/home/alex/local/folly/folly/lang/Badge.h:99:18: error: expansion pattern
‘folly::StrictDisjunction...>’ contains no
parameter packs
99 | /* implicit */ any_badge(any_badge) noexcept {}
| ^
Exited with 0
Bisection script was:
#!/bin/sh
# adapted from http://moxielogic.org/blog/bisecting-gcc.html
# Test with:
# cd local/gcc #(or whereever gcc git repo is)
# ./bisect/gxx_bisect.sh
# Run with:
# git bisect run ~/local/bisect/gxx_bisect.sh
# git clone of the gcc tree
GCCSRC="$HOME/local/gcc"
# pre-processed test case
TESTSRC="$HOME/local/bisect/bisect_source.i"
COMMIT=`git rev-parse HEAD`
# Where to put gcc build and install dirs
testdir="$HOME/local/bisect/test/$COMMIT"
mkdir -p "$testdir/build"
mkdir -p "$testdir/install"
# configure for C & C++
(cd "$testdir/build" &&
$GCCSRC/configure --prefix="$testdir/install" --enable-languages=c,c++
--with-system-zlib --disable-multilib --disable-libsanitizer
--disable-bootstrap &&
make -j 32 && make -j 32 install)
cxxbin="$testdir/install/bin/g++"
if test -x "$cxxbin"; then
# build test case
if "$cxxbin" -std=gnu++17 -c "$TES
