New comment by cinerea0 on void-packages repository

https://github.com/void-linux/void-packages/pull/31706#issuecomment-1012736780

Comment:
Currently attempting to build mold using a very similar template to the one in this PR and I think I'm getting the compilation errors mentioned earlier that disappeared on their own:

<details>
<summary>Build Output</summary>

```
=> mold-1.0.1_1: running do_build ...
mkdir -p out/elf
touch out/elf/.keep
mkdir -p out/macho
touch out/macho/.keep
g++     -DMOLD_VERSION=\"1.0.1\" -DLIBDIR="\"/usr/local/lib\"" -Ithird-party/tbb/include -Ithird-party/xxhash -fstack-clash-protection -D_FORTIFY_SOURCE=2 -mtune=generic -O2 -pipe    -fdebug-prefix-map=/builddir/mold-1.0.1=. -c -o out/compress.o compress.cc
In file included from compress.cc:15:
mold.h:27:32: error: 'string_view_literals' is not a namespace-name; did you mean 'string_literals'?
   27 | using namespace std::literals::string_view_literals;
      |                                ^~~~~~~~~~~~~~~~~~~~
      |                                string_literals
mold.h:41:1: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
   41 | inline char *output_tmpfile;
      | ^~~~~~
mold.h:42:1: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
   42 | inline char *socket_tmpfile;
      | ^~~~~~
mold.h:43:1: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
   43 | inline thread_local bool opt_demangle;
      | ^~~~~~
mold.h:47:6: error: 'string_view' in namespace 'std' does not name a type
   47 | std::string_view errno_string();
      |      ^~~~~~~~~~~
mold.h:47:1: note: 'std::string_view' is only available from C++17 onwards
   47 | std::string_view errno_string();
      | ^~~
mold.h:72:10: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
   72 |   static inline std::mutex mu;
      |          ^~~~~~
mold.h: In destructor 'mold::SyncOut<C>::~SyncOut()':
mold.h:63:21: error: missing template arguments before 'lock'
   63 |     std::lock_guard lock(mu);
      |                     ^~~~
mold.h: At global scope:
mold.h:202:39: error: 'std::string_view' has not been declared
  202 | inline i64 write_string(u8 *buf, std::string_view str) {
      |                                       ^~~~~~~~~~~
mold.h: In function 'mold::i64 mold::write_string(mold::u8*, int)':
mold.h:203:19: error: request for member 'data' in 'str', which is of non-class type 'int'
  203 |   memcpy(buf, str.data(), str.size());
      |                   ^~~~
mold.h:203:31: error: request for member 'size' in 'str', which is of non-class type 'int'
  203 |   memcpy(buf, str.data(), str.size());
      |                               ^~~~
mold.h:204:11: error: request for member 'size' in 'str', which is of non-class type 'int'
  204 |   buf[str.size()] = '\0';
      |           ^~~~
mold.h:205:14: error: request for member 'size' in 'str', which is of non-class type 'int'
  205 |   return str.size() + 1;
      |              ^~~~
mold.h: At global scope:
mold.h:255:6: error: 'string_view' in namespace 'std' does not name a type
  255 | std::string_view save_string(C &ctx, const std::string &str) {
      |      ^~~~~~~~~~~
mold.h:255:1: note: 'std::string_view' is only available from C++17 onwards
  255 | std::string_view save_string(C &ctx, const std::string &str) {
      | ^~~
mold.h:295:36: error: 'std::string_view' has not been declared
  295 |   std::pair<T *, bool> insert(std::string_view key, u64 hash, const T &val) {
      |                                    ^~~~~~~~~~~
mold.h: In member function 'std::pair<T*, bool> mold::ConcurrentMap<T>::insert(int, mold::u64, const T&)':
mold.h:316:26: error: request for member 'size' in 'key', which is of non-class type 'int'
  316 |         sizes[idx] = key.size();
      |                          ^~~~
mold.h:317:25: error: request for member 'data' in 'key', which is of non-class type 'int'
  317 |         keys[idx] = key.data();
      |                         ^~~~
mold.h:321:15: error: request for member 'size' in 'key', which is of non-class type 'int'
  321 |       if (key.size() == sizes[idx] && memcmp(ptr, key.data(), sizes[idx]) == 0)
      |               ^~~~
mold.h:321:55: error: request for member 'data' in 'key', which is of non-class type 'int'
  321 |       if (key.size() == sizes[idx] && memcmp(ptr, key.data(), sizes[idx]) == 0)
      |                                                       ^~~~
mold.h: At global scope:
mold.h:436:31: error: 'string_view' is not a member of 'std'
  436 | std::string get_realpath(std::string_view path);
      |                               ^~~~~~~~~~~
mold.h:436:31: note: 'std::string_view' is only available from C++17 onwards
mold.h:437:23: error: 'string_view' is not a member of 'std'
  437 | bool path_is_dir(std::string_view path);
      |                       ^~~~~~~~~~~
mold.h:437:23: note: 'std::string_view' is only available from C++17 onwards
mold.h:438:6: error: 'string_view' in namespace 'std' does not name a type
  438 | std::string_view path_dirname(std::string_view path);
      |      ^~~~~~~~~~~
mold.h:438:1: note: 'std::string_view' is only available from C++17 onwards
  438 | std::string_view path_dirname(std::string_view path);
      | ^~~
mold.h:439:6: error: 'string_view' in namespace 'std' does not name a type
  439 | std::string_view path_filename(std::string_view path);
      |      ^~~~~~~~~~~
mold.h:439:1: note: 'std::string_view' is only available from C++17 onwards
  439 | std::string_view path_filename(std::string_view path);
      | ^~~
mold.h:440:6: error: 'string_view' in namespace 'std' does not name a type
  440 | std::string_view path_basename(std::string_view path);
      |      ^~~~~~~~~~~
mold.h:440:1: note: 'std::string_view' is only available from C++17 onwards
  440 | std::string_view path_basename(std::string_view path);
      | ^~~
mold.h:441:35: error: 'string_view' is not a member of 'std'
  441 | std::string path_to_absolute(std::string_view path);
      |                                   ^~~~~~~~~~~
mold.h:441:35: note: 'std::string_view' is only available from C++17 onwards
mold.h:442:29: error: 'string_view' is not a member of 'std'
  442 | std::string path_clean(std::string_view path);
      |                             ^~~~~~~~~~~
mold.h:442:29: note: 'std::string_view' is only available from C++17 onwards
mold.h:448:6: error: 'string_view' in namespace 'std' does not name a type
  448 | std::string_view demangle(std::string_view name);
      |      ^~~~~~~~~~~
mold.h:448:1: note: 'std::string_view' is only available from C++17 onwards
  448 | std::string_view demangle(std::string_view name);
      | ^~~
mold.h:456:34: error: expected ')' before 'input'
  456 |   ZlibCompressor(std::string_view input);
      |                 ~                ^~~~~~
      |                                  )
mold.h:467:34: error: expected ')' before 'input'
  467 |   GzipCompressor(std::string_view input);
      |                 ~                ^~~~~~
      |                                  )
mold.h:484:27: error: expected ')' before 'name'
  484 |   Counter(std::string_view name, i64 value = 0) : name(name), values(value) {
      |          ~                ^~~~~
      |                           )
mold.h:504:10: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
  504 |   static inline bool enabled = false;
      |          ^~~~~~
mold.h:509:8: error: 'string_view' in namespace 'std' does not name a type
  509 |   std::string_view name;
      |        ^~~~~~~~~~~
mold.h:509:3: note: 'std::string_view' is only available from C++17 onwards
  509 |   std::string_view name;
      |   ^~~
mold.h:512:10: warning: inline variables are only available with '-std=c++17' or '-std=gnu++17'
  512 |   static inline std::vector<Counter *> instances;
      |          ^~~~~~
mold.h:568:38: error: 'std::string_view' has not been declared
  568 |   void append(std::string path, std::string_view data);
      |                                      ^~~~~~~~~~~
mold.h:578:43: error: 'string_view' is not a member of 'std'
  578 |   std::vector<std::pair<std::string, std::string_view>> contents;
      |                                           ^~~~~~~~~~~
mold.h:578:43: note: 'std::string_view' is only available from C++17 onwards
mold.h:578:43: error: 'string_view' is not a member of 'std'
mold.h:578:43: note: 'std::string_view' is only available from C++17 onwards
mold.h:578:43: error: template argument 2 is invalid
mold.h:578:54: error: template argument 1 is invalid
  578 |   std::vector<std::pair<std::string, std::string_view>> contents;
      |                                                      ^~
mold.h:578:54: error: template argument 2 is invalid
mold.h:598:8: error: 'string_view' in namespace 'std' does not name a type
  598 |   std::string_view get_contents() {
      |        ^~~~~~~~~~~
mold.h:598:3: note: 'std::string_view' is only available from C++17 onwards
  598 |   std::string_view get_contents() {
      |   ^~~
mold.h: In static member function 'static mold::MappedFile<C>* mold::MappedFile<C>::open(C&, std::string)':
mold.h:617:12: error: 'std::string' {aka 'class std::__cxx11::basic_string<char>'} has no member named 'starts_with'
  617 |   if (path.starts_with('/') && !ctx.arg.chroot.empty())
      |            ^~~~~~~~~~~
mold.h:618:50: error: no match for call to '(std::string {aka std::__cxx11::basic_string<char>}) (std::string&)'
  618 |     path = ctx.arg.chroot + "/" + path_clean(path);
      |                                                  ^
mold.h:626:10: error: missing template arguments before '(' token
  626 |     Fatal(ctx) << path << ": fstat failed: " << errno_string();
      |          ^
mold.h:626:49: error: there are no arguments to 'errno_string' that depend on a template parameter, so a declaration of 'errno_string' must be available [-fpermissive]
  626 |     Fatal(ctx) << path << ": fstat failed: " << errno_string();
      |                                                 ^~~~~~~~~~~~
mold.h:626:49: note: (if you use '-fpermissive', G++ will accept your code, but allowing the use of an undeclared name is deprecated)
mold.h:639:12: error: missing template arguments before '(' token
  639 |       Fatal(ctx) << path << ": mmap failed: " << errno_string();
      |            ^
mold.h:639:50: error: there are no arguments to 'errno_string' that depend on a template parameter, so a declaration of 'errno_string' must be available [-fpermissive]
  639 |       Fatal(ctx) << path << ": mmap failed: " << errno_string();
      |                                                  ^~~~~~~~~~~~
mold.h: In static member function 'static mold::MappedFile<C>* mold::MappedFile<C>::must_open(C&, std::string)':
mold.h:650:8: error: missing template arguments before '(' token
  650 |   Fatal(ctx) << "cannot open " << path;
      |        ^
compress.cc: At global scope:
compress.cc:24:25: error: 'string_view' is not a member of 'std'
   24 | static std::vector<std::string_view> split(std::string_view input) {
      |                         ^~~~~~~~~~~
compress.cc:24:25: note: 'std::string_view' is only available from C++17 onwards
compress.cc:24:25: error: 'string_view' is not a member of 'std'
compress.cc:24:25: note: 'std::string_view' is only available from C++17 onwards
compress.cc:24:36: error: template argument 1 is invalid
   24 | static std::vector<std::string_view> split(std::string_view input) {
      |                                    ^
compress.cc:24:36: error: template argument 2 is invalid
compress.cc:24:49: error: 'string_view' is not a member of 'std'
   24 | static std::vector<std::string_view> split(std::string_view input) {
      |                                                 ^~~~~~~~~~~
compress.cc:24:49: note: 'std::string_view' is only available from C++17 onwards
compress.cc:36:41: error: 'string_view' is not a member of 'std'
   36 | static std::vector<u8> do_compress(std::string_view input) {
      |                                         ^~~~~~~~~~~
compress.cc:36:41: note: 'std::string_view' is only available from C++17 onwards
compress.cc:36:60: error: expected ',' or ';' before '{' token
   36 | static std::vector<u8> do_compress(std::string_view input) {
      |                                                            ^
compress.cc:66:31: error: expected constructor, destructor, or type conversion before '(' token
   66 | ZlibCompressor::ZlibCompressor(std::string_view input) {
      |                               ^
compress.cc:114:31: error: expected constructor, destructor, or type conversion before '(' token
  114 | GzipCompressor::GzipCompressor(std::string_view input) {
      |                               ^
make: *** [Makefile:126: out/compress.o] Error 1
=> ERROR: mold-1.0.1_1: do_build: '${make_cmd} CC="$CC" CXX="$CXX" LD="$LD" AR="$AR" RANLIB="$RANLIB" CPP="$CPP" AS="$AS" OBJCOPY="$OBJCOPY" OBJDUMP="$OBJDUMP" CFLAGS="$CFLAGS" CXXFLAGS="$CXXFLAGS" LDFLAGS="$LDFLAGS" ${makejobs} ${make_build_args} ${make_build_target}' exited with 2
=> ERROR:   in do_build() at common/build-style/gnu-makefile.sh:9
```

</details>