rtags-flycheck doesn't use the correct c++ standard, aka c++14

[amosbird]

Please mark appropriate

• rtags (rdm/rc/rp)
• Emacs Lisp
  • ac-rtags.el
  • company-rtags.el
  • helm-rtags.el
  • flycheck-rtags.el
  • ivy-rtags.el
  • rtags.el

Problem description

rtags-flycheck warns std::enable_if_t isn't declared, which should be fine in c++14.

Environment

• Your operating system:
  Centos 7
• LLVM/Clang version:
  clang 4.0

[amosbird]

Hmm, this becomes more subtle.

/home/amos/git/ClickHouse/dbms/src/DataStreams/InputStreamFromASTInsertQuery.cpp:22:29: error: Semantic Issue: no member named 'make_unique' in namespace 'std'

Can I make rtags use -std=gnu++1z ?

And how can I jump to the error position (row, column) instead of just row ?

[collinjackson93]

Can you paste one of the commands from your compilation database? I believe rtags simply forwards those commands (which should have the standard version listed) to clang, which then finds any errors.

[amosbird]

sure

{
  "directory": "/home/amos/git/ClickHouse/dbg",
  "command": "/usr/local/bin/clang++  -DBOOST_SYSTEM_NO_DEPRECATED -DLZ4_DISABLE_DEPRECATE_WARNINGS=1 -DPOCO_UNBUNDLED_ZLIB -I../libs/libdaemon/include -I../contrib/libunwind/include -Icontrib/libunwind/config -I../dbms/src -Idbms/src -I../contrib/libpcg-random/include -I../contrib/libcityhash/include -I../libs/libcommon/include -Ilibs/libcommon/include -I../libs/libpocoext/include -I../contrib/poco/Util/include -I../contrib/poco/Foundation/include -I../contrib/libzlib-ng -Icontrib/libzlib-ng -I../contrib/poco/XML/include -I../contrib/poco/JSON/include -I../contrib/poco/Net/include -I../contrib/cctz/include -I../contrib/libboost/boost_1_65_0 -I../contrib/libtcmalloc/include -Icontrib/libfarmhash -I../contrib/lz4/lib -I../contrib/zstd/lib -I../contrib/zookeeper/src/c/include -Icontrib/zookeeper/src/c/include -I../contrib/zookeeper/src/c/generated -I../contrib/libdouble-conversion/. -I../contrib/libcpuid/include -I../contrib/libre2/. -Icontrib/libre2 -I../contrib/poco/Data/include -I../contrib/libbtrie/include -I../contrib/poco/Data/ODBC/include -I../contrib/poco/MongoDB/include -I../contrib/poco/NetSSL_OpenSSL/include -I../contrib/poco/Crypto/include -I../contrib/librdkafka/src -Icontrib/librdkafka/generated/dummy -I../contrib/libdivide -I../contrib/libmetrohash/src -I../contrib/libfarmhash    -D_GLIBCXX_USE_CXX11_ABI=1 -pipe -msse4.1 -msse4.2 -mpopcnt  -fno-omit-frame-pointer -Wall -Wnon-virtual-dtor  -Werror -g -O0 -g3 -ggdb3 -fno-inline -fPIC   -DNO_TCMALLOC_SAMPLES -DNDEBUG -DNO_FRAME_POINTER -Wwrite-strings -Wno-sign-compare -Wno-unused-result -Wno-deprecated-declarations -Wno-unused-function -Wno-unused-private-field -fno-builtin-malloc -fno-builtin-free -fno-builtin-realloc -fno-builtin-calloc -fno-builtin-cfree -fno-builtin-memalign -fno-builtin-posix_memalign -fno-builtin-valloc -fno-builtin-pvalloc -Wno-dynamic-exception-spec -std=gnu++1z -o dbms/src/Server/CMakeFiles/clickhouse-server.dir/Server.cpp.o -c /home/amos/git/ClickHouse/dbms/src/Server/Server.cpp",
  "file": "/home/amos/git/ClickHouse/dbms/src/Server/Server.cpp"
},

[collinjackson93]

According to this gnu++1z is deprecated. Can you try changing it to gnu++17 or c++17 and see if you get the same behavior? My guess is that clang defaults to c++11 when no std flag is passed or it gets one it can't interpret.

[amosbird]

@collinjackson93 hi, sadly it still doesn't work.

[collinjackson93]

I attempted to reproduce on my system, but had issues getting everything set up to build ClickHouse.

I just noticed that you're using Clang 4.0, which doesn't have full support for C++17. As a test, can you try using -std=c++14?

If that doesn't work, we should be able to quickly put together a small test program that calls std::make_unique to make it easier to reproduce so I can attempt it on my system (which is running Clang 5.0).

[amosbird]

OK, I've setup a clang-5 env. rdm shows this error when parsing certain source file.

rp: /home/amos/git/build-llvm/llvm-5.0.0/llvm-5.0.0.src/tools/clang/lib/Sema/SemaDecl.cpp:1268: void clang::Sema::EnterDeclaratorContext(clang::Scope*, clang::DeclContext*): Assertion `Ancestor->getEntity() == CurContext && "ancestor context mismatch"' failed.
libclang: crash detected during parsing: {
  'source_filename' : '/home/amos/git/ClickHouse/contrib/poco/Foundation/src/DateTimeFormat.cpp'
  'command_line_args' : ['clang', '-pipe', '-msse4.1', '-msse4.2', '-mpopcnt', '-fno-omit-frame-pointer', '-Wall', '-Wnon-virtual-dtor', '-Wno-old-style-cast', '-g', '-O0', '-g3', '-ggdb3', '-fno-inline', '-fPIC', '-Wno-sign-compare', '-Wno-non-virtual-dtor', '-fno-strict-aliasing', '-Wno-unknown-pragmas', '-std=gnu++1z', '-c', '-ferror-limit=50', '-Wall', '-fspell-checking', '-Wno-unknown-warning-option', '-DRTAGS=', '-D_FILE_OFFSET_BITS=64', '-D_GLIBCXX_USE_CXX11_ABI=1', '-D_XOPEN_SOURCE=500', '-DFoundation_EXPORTS', '-DHAVE_PTHREAD_SETAFFINITY_NP', '-DHAVE_THREE_PARAM_SCHED_SETAFFINITY', '-DPCRE_STATIC', '-DPOCO_EXTERNAL_OPENSSL', '-DPOCO_HAVE_FD_EPOLL', '-DPOCO_UNBUNDLED', '-DPOCO_UNBUNDLED_ZLIB', '-D_DEBUG', '-D_LARGEFILE64_SOURCE', '-D_REENTRANT', '-D_THREAD_SAFE', '-I/home/amos/git/ClickHouse/dbg/../contrib/poco/Foundation/include', '-I/home/amos/git/ClickHouse/dbg/../contrib/poco/Foundation/src', '-I/home/amos/git/ClickHouse/dbg/../contrib/libzlib-ng', '-I/home/amos/git/ClickHouse/dbg/contrib/libzlib-ng'],
  'unsaved_files' : [],
  'options' : 513,
}
Failed to parse clang "-pipe" "-msse4.1" "-msse4.2" "-mpopcnt" "-fno-omit-frame-pointer" "-Wall" "-Wnon-virtual-dtor" "-Wno-old-style-cast" "-g" "-O0" "-g3" "-ggdb3" "-fno-inline" "-fPIC" "-Wno-sign-compare" "-Wno-non-virtual-dtor" "-fno-strict-aliasing" "-Wno-unknown-pragmas" "-std=gnu++1z" "-c" "-ferror-limit=50" "-Wall" "-fspell-checking" "-Wno-unknown-warning-option" "-DRTAGS=" "-D_FILE_OFFSET_BITS=64" "-D_GLIBCXX_USE_CXX11_ABI=1" "-D_XOPEN_SOURCE=500" "-DFoundation_EXPORTS" "-DHAVE_PTHREAD_SETAFFINITY_NP" "-DHAVE_THREE_PARAM_SCHED_SETAFFINITY" "-DPCRE_STATIC" "-DPOCO_EXTERNAL_OPENSSL" "-DPOCO_HAVE_FD_EPOLL" "-DPOCO_UNBUNDLED" "-DPOCO_UNBUNDLED_ZLIB" "-D_DEBUG" "-D_LARGEFILE64_SOURCE" "-D_REENTRANT" "-D_THREAD_SAFE" "-I/home/amos/git/ClickHouse/dbg/../contrib/poco/Foundation/include" "-I/home/amos/git/ClickHouse/dbg/../contrib/poco/Foundation/src" "-I/home/amos/git/ClickHouse/dbg/../contrib/libzlib-ng" "-I/home/amos/git/ClickHouse/dbg/contrib/libzlib-ng" /home/amos/git/ClickHouse/contrib/poco/Foundation/src/DateTimeFormat.cpp

[collinjackson93]

That looks like an error from libclang itself, not rtags. I wonder if that assertion started failing in clang 5 or if you just got lucky with clang 4. You might want to report that to llvm.

As for your initial problem with c++14 support, can you try compiling the following simple program using clang++ -std=gnu++1z?

#include <memory>
#include <iostream>

int main()
{
  auto a = std::make_unique<int>(10);
  std::cout << *a << std::endl;
  return 0;
}

If you can, I would try compiling with clang 4 since you ran into a different error with clang 5.

I was unable to compile it on one of my computers running clang 5 (most likely because the libc++ version is too old), however, it compiled successfully on my other computer (also running clang 5).

If it compiles using clang, try running it through rtags. I did rc -c clang++ -std=gnu++1z makeUnique.cpp followed by rc --diagnose makeUnique.cpp. The rc documentation is a little hard to follow, but I think --diagnose is the one that runs diagnostics on the file (which is what rtags-flycheck displays).

[amosbird]

As for your initial problem with c++14 support, can you try compiling the following simple program using clang++ -std=gnu++1z?

It compiles.

If you can, I would try compiling with clang 4 since you ran into a different error with clang 5.

It also works.

If it compiles using clang, try running it through rtags.

Hmm, i got nothing after running rc -c clang++ -std=gnu++1z makeUnique.cpp. It exists with return code 1. And rc --diagnose makeUnique.cpp says the file isn't indexed.

[amosbird]

I even tried https://github.com/llvm-project/llvm-project-20170507 from which rtags still cannot parse clickhouse correctly.

[amosbird]

OK, I resolved this by following steps,

1. get clang's include path via clang++ -v -xc++ /dev/null -fsyntax-only. Mine is

 /usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0
 /usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0/x86_64-pc-linux-gnu
 /usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward
 /usr/local/include
 /usr/local/lib/clang/6.0.0/include
 /usr/include

2. Add those paths into $HOME/.rdmrc like this

-I/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0
-I/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0/x86_64-pc-linux-gnu
-I/usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/7.2.0/../../../../include/c++/7.2.0/backward
-I/usr/local/include
-I/usr/local/lib/clang/6.0.0/include
-I/usr/include

3. remove rtags cache files rm -rf $HOME/.cache/rtags and reindex target project.

Hope it help. Cheers!