not support to build as submodule on macOS

[kgbook]

I installed the fmt using brew install fmt, but found fmt 5.3.0 version not work on my computer, see issue #1115 .

So I add submodule fmt using git submodule add https://github.com/fmtlib/fmt.git.

It’s ok if I build solely, but not if built as submodule.

OS： macOS Mojave 10.14.4
fmt: the latest version of the master branch
cmake : 3.14.1
g++:

Apple LLVM version 10.0.1 (clang-1001.0.46.3)
Target: x86_64-apple-darwin18.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Log:

Scanning dependencies of target skeleton_cpplint
Scanning dependencies of target fmt
[  0%] Linting skeleton_cpplint
[  1%] Building CXX object fmt/CMakeFiles/fmt.dir/src/format.cc.o
Done processing /Users/kang/project/sample/RTSPServer/skeleton/exception.cpp
Done processing /Users/kang/project/sample/RTSPServer/skeleton/skeleton_service.cpp
Total errors found: 0
[  1%] Built target skeleton_cpplint
[  1%] Building CXX object fmt/CMakeFiles/fmt.dir/src/posix.cc.o
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:14:59: error: parameter
      type 'internal::buffer' (aka 'basic_buffer<char>') is an abstract class
bool (*instantiate_grisu2_format)(double, internal::buffer<char>&, int, bool,
                                                          ^
/usr/local/include/fmt/core.h:238:16: note: unimplemented pure virtual method
      'grow' in 'basic_buffer'
  virtual void grow(std::size_t capacity) = 0;
               ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:14:59: error: expected
      ')'
bool (*instantiate_grisu2_format)(double, internal::buffer<char>&, int, bool,
                                                          ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:14:34: note: to match
      this '('
bool (*instantiate_grisu2_format)(double, internal::buffer<char>&, int, bool,
                                 ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:15:43: error: address of
      overloaded function 'grisu2_format' does not match required type 'bool
      (double, fmt::v5::internal::basic_buffer<char>)'
                                  int&) = internal::grisu2_format;
                                          ^~~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/fmt/format.h:1134:3: note: candidate template ignored: could
      not match 'fmt::v5::internal::basic_buffer<char> &' against
      'fmt::v5::internal::basic_buffer<char>'
  grisu2_format(Double, buffer &, core_format_specs) { return false; }
  ^
/usr/local/include/fmt/format-inl.h:716:5: note: candidate template ignored:
      could not match 'fmt::v5::internal::basic_buffer<char> &' against
      'fmt::v5::internal::basic_buffer<char>'
    grisu2_format(Double value, buffer &buf, core_format_specs specs) {
    ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:26:39: error: variable
      cannot be defined in an explicit instantiation; if this declaration is
      meant to be a variable definition, remove the 'template' keyword
template FMT_API void internal::buffer<char>::append(const char*, const char*);
~~~~~~~~~                             ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:26:33: error: variable
      has incomplete type 'void'
template FMT_API void internal::buffer<char>::append(const char*, const char*);
                                ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:26:39: error: expected
      ';' at end of declaration
template FMT_API void internal::buffer<char>::append(const char*, const char*);
                                      ^
                                      ;
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:26:39: error: expected
      unqualified-id
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:35:21: error: parameter
      type 'internal::buffer' (aka 'basic_buffer<char>') is an abstract class
    internal::buffer<char>&, string_view, basic_format_args<format_context>);
                    ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:35:21: error: expected
      ')'
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:34:63: note: to match
      this '('
template FMT_API format_context::iterator internal::vformat_to(
                                                              ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:34:53: error: explicit
      instantiation of 'vformat_to' does not refer to a function template,
      variable template, member function, member class, or static data member
template FMT_API format_context::iterator internal::vformat_to(
                                                    ^
/usr/local/include/fmt/format.h:3233:57: note: candidate template ignored: could
      not match 'basic_buffer<type-parameter-0-0> &' against
      'fmt::v5::internal::basic_buffer<char>'
typename buffer_context<Char>::type::iterator internal::vformat_to(
                                                        ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:37:72: error: parameter
      type 'internal::buffer' (aka 'basic_buffer<char>') is an abstract class
template FMT_API void internal::sprintf_format(double, internal::buffer<char>&,
                                                                       ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:37:72: error: expected
      ')'
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:37:47: note: to match
      this '('
template FMT_API void internal::sprintf_format(double, internal::buffer<char>&,
                                              ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:37:33: error: explicit
      instantiation of 'sprintf_format' does not refer to a function template,
      variable template, member function, member class, or static data member
template FMT_API void internal::sprintf_format(double, internal::buffer<char>&,
                                ^
/usr/local/include/fmt/format-inl.h:764:6: note: candidate template ignored:
      could not match 'fmt::v5::internal::basic_buffer<char> &' against
      'fmt::v5::internal::basic_buffer<char>'
void sprintf_format(Double value, internal::buffer &buf,
     ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:40:64: error: parameter
      type 'internal::buffer' (aka 'basic_buffer<char>') is an abstract class
                                               internal::buffer<char>&,
                                                               ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:40:64: error: expected
      ')'
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:39:47: note: to match
      this '('
template FMT_API void internal::sprintf_format(long double,
                                              ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:39:33: error: explicit
      instantiation of 'sprintf_format' does not refer to a function template,
      variable template, member function, member class, or static data member
template FMT_API void internal::sprintf_format(long double,
                                ^
/usr/local/include/fmt/format-inl.h:764:6: note: candidate template ignored:
      could not match 'fmt::v5::internal::basic_buffer<char> &' against
      'fmt::v5::internal::basic_buffer<char>'
void sprintf_format(Double value, internal::buffer &buf,
     ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:47:39: error: variable
      cannot be defined in an explicit instantiation; if this declaration is
      meant to be a variable definition, remove the 'template' keyword
template FMT_API void internal::buffer<wchar_t>::append(const wchar_t*,
~~~~~~~~~                             ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:47:33: error: variable
      has incomplete type 'void'
template FMT_API void internal::buffer<wchar_t>::append(const wchar_t*,
                                ^
/Users/kang/project/sample/RTSPServer/fmt/src/format.cc:47:39: error: expected
      ';' at end of declaration
template FMT_API void internal::buffer<wchar_t>::append(const wchar_t*,
                                      ^
                                      ;
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
make[2]: *** [fmt/CMakeFiles/fmt.dir/src/format.cc.o] Error 1
make[2]: *** Waiting for unfinished jobs....

[vitaut]

Whether it's a git submodule or not is irrelevant. Please provide the commands (and if necessary code) to repro.

[kgbook]

It's ok now.
I forgot to add include_directories(${CMAKE_CURRENT_SOURCE_DIR}/fmt/include).
It's my mistake.
Thank you.