Cannot compile with uClibc++

[neheb]

I have tried to compile zerotier with uClibc++(C++98 library) instead of libstdcpp. It's failing as the algorithm header requires a missing operator. Here is the output:

In file included from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm: In instantiation of 'ForwardIterator std::lower_bound(ForwardIterator, ForwardIterator, const T&, Compare) [with ForwardIterator = ZeroTier::Multicaster::MulticastGroupMember*; T = ZeroTier::Address; Compare = std::less<ZeroTier::Multicaster::MulticastGroupMember>]':
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:945:21:   required from 'ForwardIterator std::lower_bound(ForwardIterator, ForwardIterator, const T&) [with ForwardIterator = ZeroTier::Multicaster::MulticastGroupMember*; T = ZeroTier::Address]'
node/Multicaster.cpp:427:107:   required from here
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:956:11: error: no match for call to '(std::less<ZeroTier::Multicaster::MulticastGroupMember>) (ZeroTier::Multicaster::MulticastGroupMember&, const ZeroTier::Address&)'
  956 |   if( comp(*first, value) == false){
      |       ~~~~^~~~~~~~~~~~~~~
In file included from /home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:21,
                 from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:8: note: candidate: 'bool std::less<T>::operator()(const T&, const T&) const [with T = ZeroTier::Multicaster::MulticastGroupMember]'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |        ^~~~~~~~
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:40: note:   no known conversion for argument 2 from 'const ZeroTier::Address' to 'const ZeroTier::Multicaster::MulticastGroupMember&'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |                               ~~~~~~~~~^
In file included from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:964:11: error: no match for call to '(std::less<ZeroTier::Multicaster::MulticastGroupMember>) (ZeroTier::Multicaster::MulticastGroupMember&, const ZeroTier::Address&)'
  964 |   if( comp(*middle, value) ){
      |       ~~~~^~~~~~~~~~~~~~~~
In file included from /home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:21,
                 from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:8: note: candidate: 'bool std::less<T>::operator()(const T&, const T&) const [with T = ZeroTier::Multicaster::MulticastGroupMember]'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |        ^~~~~~~~
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:40: note:   no known conversion for argument 2 from 'const ZeroTier::Address' to 'const ZeroTier::Multicaster::MulticastGroupMember&'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |                               ~~~~~~~~~^
In file included from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:973:13: error: no match for call to '(std::less<ZeroTier::Multicaster::MulticastGroupMember>) (ZeroTier::Multicaster::MulticastGroupMember&, const ZeroTier::Address&)'
  973 |    if( !comp(*middle, value) ){
      |         ~~~~^~~~~~~~~~~~~~~~
In file included from /home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:21,
                 from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:8: note: candidate: 'bool std::less<T>::operator()(const T&, const T&) const [with T = ZeroTier::Multicaster::MulticastGroupMember]'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |        ^~~~~~~~
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:40: note:   no known conversion for argument 2 from 'const ZeroTier::Address' to 'const ZeroTier::Multicaster::MulticastGroupMember&'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |                               ~~~~~~~~~^
In file included from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:980:12: error: no match for call to '(std::less<ZeroTier::Multicaster::MulticastGroupMember>) (ZeroTier::Multicaster::MulticastGroupMember&, const ZeroTier::Address&)'
  980 |   if( !comp(*first, value) ){
      |        ~~~~^~~~~~~~~~~~~~~
In file included from /home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/algorithm:21,
                 from node/Multicaster.cpp:27:
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:8: note: candidate: 'bool std::less<T>::operator()(const T&, const T&) const [with T = ZeroTier::Multicaster::MulticastGroupMember]'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |        ^~~~~~~~
/home/mangix/devstuff/openwrt/staging_dir/target-armeb_xscale_musl/usr/include/uClibc++/functional:146:40: note:   no known conversion for argument 2 from 'const ZeroTier::Address' to 'const ZeroTier::Multicaster::MulticastGroupMember&'
  146 |   bool operator()(const T& x, const T& y) const _UCXX_NOTHROW {
      |                               ~~~~~~~~~^
<builtin>: recipe for target 'node/Multicaster.o' failed

[adamierymenko]

Isn't this a bug in uclibc++? It works against libc++ (clang), whatever Microsoft uses with VC++, and libstdc++ (GNU).

[neheb]

Not exactly. In its algorithm implementation, uClibc++ requires an operator that ZeroTierOne is not providing. My C++ is not good enough to figure this one out.

An example with a different program would be: morgenroth/ibrdtn@008c385

[adamierymenko]

Does that commit to dev fix it?

[neheb]

It does not.

It's not a != operator that's missing. It's something else. The patch i linked to errored with this: openwrt/packages#7822

Note the != there. Here, the error is different:

error: no match for call to '(std::lessZeroTier::Multicaster::MulticastGroupMember) (ZeroTier::Multicaster::MulticastGroupMember&, const ZeroTier::Address&)'

[adamierymenko]

Ahh, I think I might have it now. Try it. Don't have a uclibc++ build environment so I can't test.

[neheb]

Same error.

[neheb]

I tried changing line 427, which is the line that errors. Maybe this provides a clue?

node/Multicaster.cpp:427:48: error: cannot convert 'const ZeroTier::Address' to 'std::vector<ZeroTier::Multicaster::MulticastGroupMember>::iterator' {aka 'ZeroTier::Multicaster::MulticastGroupMember*'} in initialization
  427 |  std::vector<MulticastGroupMember>::iterator m(member);
      |                                                ^~~~~~
      |                                                |
      |                                                const ZeroTier::Address

[neheb]

I got it to proceed with this change (yes I know, totally wrong):

-       std::vector<MulticastGroupMember>::iterator m(std::lower_bound(gs.members.begin(),gs.members.end(),member));
+       std::vector<MulticastGroupMember>::iterator m(gs.members.end());

but then it started throwing some C++11 headers. No dice.