Project cannot be built with both recent gcc and clang

[tesuji]

I cannot build this project with both gcc and clang on latest commit as this time: 6630781.

I'm happy to answer more questions about my build environment if that helps.

Expected Behavior

Build shall pass.

Current Behavior

Build fails.

With clang:

`make -j32`

archive_file.cc:39:17: error: no matching constructor for initialization of 'std::string' (aka 'basic_string<char>')
    std::string name(start, strstr(start, "/\n"));
                ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~
archive_file.cc:70:12: error: no viable overloaded '='
      name = {start, strstr(start, "/\n")};
      ~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With gcc by changing CC and CXX in makefile.

`make -j32`

subprocess.cc: In function ‘std::function<void()> fork_child()’:
subprocess.cc:33:34: error: taking address of temporary array
   33 |     if (read(pipefd[0], (char[1]){}, 1) == 1)
      |                                  ^~
subprocess.cc: In lambda function:
subprocess.cc:48:44: error: taking address of temporary array
   48 |   return [=]() { write(pipefd[1], (char []){1}, 1); };
      |                                            ^~~
subprocess.cc: In function ‘bool resume_daemon(char**, i64*)’:
subprocess.cc:153:31: error: taking address of temporary array
  153 |   i64 r = read(conn, (char[1]){}, 1);
      |                               ^~
subprocess.cc: In lambda function:
subprocess.cc:218:47: error: taking address of temporary array
  218 |   *on_complete = [=]() { write(conn, (char []){1}, 1); };
      |                                               ^~~
icf.cc:69:19: warning: ‘template<class Key> class tbb::tbb_hash’ is deprecated: tbb::tbb_hash is deprecated, use std::hash [-Wdeprecated-declarations]
   69 | template<> struct tbb_hash<Digest> {
      |                   ^~~~~~~~
In file included from oneTBB/include/tbb/concurrent_hash_map.h:35,
                 from mold.h:21,
                 from icf.cc:53:
oneTBB/include/tbb/internal/_tbb_hash_compare_impl.h:86:74: note: declared here
   86 | class __TBB_DEPRECATED_MSG("tbb::tbb_hash is deprecated, use std::hash") tbb_hash
      |                                                                          ^~~~~~~~
At global scope:
cc1plus: note: unrecognized command-line option ‘-Wno-deprecated-volatile’ may have been intended to silence earlier diagnostics

Context (Environment)

gcc --version: gcc (GCC) 10.2.0
clang version 11.0.0 x86_64-unknown-linux-gnu
OS: Linux 4.19.0-0.bpo.9-amd64 #1 SMP Debian 4.19.118-2+deb10u1~bpo9+1 (2020-06-09) x86_64 GNU/Linux
glibc:

[rui314]

mold is written in C++20. You need a very recent version of clang or gcc as well as libstdc++. I'm using Ubuntu 20 right now, and even though I don't remember what packages I installed, I could set up a build env only with apt-get.

[xyproto]

mold builds here on Arch Linux using Clang 11.1.0 (the latest released version), but not GCC 10.2.0 (the latest released version).

I tried by changing CXX and CC at the top of the Makefile to g++ and gcc.

btw, if the top of the makefile was:

CC?=clang
CXX?=clang++

instead of

CC=clang
CXX=clang++

Then CC and CXX would be respected when running CXX=clang++ CC=clang make.

[rui314]

I believe mold can now be built both with clang and with gcc.