Replace throw with noexcept for C17 compatibility by bdangit · Pull Request #17 · arun11299/cpp-subprocess

bdangit · 2018-10-05T23:54:53Z

C++11 started to deprecate the use of throw function identifiers. In C++17, this header no longer compiles due to the deprecation. Further, cleaned up other gcc compiler warnings around the use of throw.

Errors due to `throw`

# g++ -g -Wall -std=c++17 -lpthread -o test_cat test_cat.cc
../subprocess.hpp:220:38: error: ISO C++1z does not allow dynamic exception specifications
   std::pair<int, int> pipe_cloexec() throw (OSError)
                                      ^~~~~
../subprocess.hpp:968:24: error: ISO C++1z does not allow dynamic exception specifications
   void start_process() throw (CalledProcessError, OSError);
                        ^~~~~
../subprocess.hpp:974:14: error: ISO C++1z does not allow dynamic exception specifications
   int wait() throw(OSError);
              ^~~~~
../subprocess.hpp:976:14: error: ISO C++1z does not allow dynamic exception specifications
   int poll() throw(OSError);
              ^~~~~
../subprocess.hpp:1020:26: error: ISO C++1z does not allow dynamic exception specifications
   void execute_process() throw (CalledProcessError, OSError);
                          ^~~~~
../subprocess.hpp:1069:36: error: ISO C++1z does not allow dynamic exception specifications
 inline void Popen::start_process() throw (CalledProcessError, OSError)
                                    ^~~~~
../subprocess.hpp:1083:26: error: ISO C++1z does not allow dynamic exception specifications
 inline int Popen::wait() throw (OSError)
                          ^~~~~
../subprocess.hpp:1098:26: error: ISO C++1z does not allow dynamic exception specifications
 inline int Popen::poll() throw (OSError)
                          ^~~~~
../subprocess.hpp:1140:38: error: ISO C++1z does not allow dynamic exception specifications
 inline void Popen::execute_process() throw (CalledProcessError, OSError)

Other gcc errors discovered after fixing the `throw` identifiers

../subprocess.hpp: In function 'std::pair<int, int> subprocess::util::pipe_cloexec()':
../subprocess.hpp:225:42: warning: throw will always call terminate() [-Wterminate]
       throw OSError("pipe failure", errno);
                                          ^
../subprocess.hpp: In member function 'int subprocess::Popen::wait()':
../subprocess.hpp:1088:63: warning: throw will always call terminate() [-Wterminate]
     if (errno != ECHILD) throw OSError("waitpid failed", errno);
                                                               ^
../subprocess.hpp: In member function 'int subprocess::Popen::poll()':
../subprocess.hpp:1125:47: warning: throw will always call terminate() [-Wterminate]
     else throw OSError("waitpid failed", errno);
                                               ^
../subprocess.hpp: In member function 'void subprocess::Popen::execute_process()':
../subprocess.hpp:1164:39: warning: throw will always call terminate() [-Wterminate]
     throw OSError("fork failed", errno);
                                       ^
../subprocess.hpp:1206:13: warning: throw will always call terminate() [-Wterminate]
       throw exp;
             ^~~

Testing

_test_binaries=(
  test
  test_cat
  test_env
  test_err_redirection
  test_ret_code
  test_split
  test_subprocess
)

pushd "test" || exit 1
  for f in ${_test_binaries[@]}; do
    build_line "building test/$f"
    g++ -g -Wall -std=c++17 -lpthread -o "${f}" "${f}.cc"
  done
popd || exit 1

pushd "test" || exit 1
  for f in ${_test_binaries[@]}; do
    build_line "executing test/$f"
    ./"${f}"
  done
popd || exit 1

Environment

# g++ --version
g++.real (GCC) 7.3.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

# uname -a
Linux 512a1da44a6c 4.9.93-linuxkit-aufs #1 SMP Wed Jun 6 16:55:56 UTC 2018 x86_64 GNU/Linux

Signed-off-by: Ben Dang me@bdang.it

bdangit · 2018-10-06T00:00:27Z

Furthermore, tested compiling with -std=c++11 and -std=c++14. No errors and all tests work.

arun11299

Thanks for trying to make it compatible with latest standard. I have few comments/questions in the change set. Could you please clarify those?

subprocess.hpp

C++11 started to deprecate the use of throw function identifiers. In C++17, this header no longer compiles due to the deprecation. Signed-off-by: Ben Dang <me@bdang.it>

bdangit · 2018-10-08T04:50:38Z

Hi @arun11299, I updated the PR based on your comments. I have to admit that I didn't realize noexcept had the ability to resolve expressions that way. With that I brought back the throw within the function since that was the intention.

I compiled against c++11, c++14, and c++17. No warnings/errors and all tests pass.

   cpp-subprocess: building test/test
   cpp-subprocess: building test/test_cat
   cpp-subprocess: building test/test_env
   cpp-subprocess: building test/test_err_redirection
   cpp-subprocess: building test/test_ret_code
   cpp-subprocess: building test/test_split
   cpp-subprocess: building test/test_subprocess
/src /src
   cpp-subprocess: Running post-compile tests
/src/test /src /src
   cpp-subprocess: executing test/test
bufsize opt
exe opt
   cpp-subprocess: executing test/test_cat
Test::test_cat_pipe_redirection
END_TEST
Test::test_cat_file_redirection
END_TEST
44112
Test::test_buffer_growth_threaded_comm
44112
END_TEST
   cpp-subprocess: executing test/test_env
ENV1 = VALUE-1
ENV2 = VALUE-2
ENV3 = VALUE-3
   cpp-subprocess: executing test/test_err_redirection
-1
   cpp-subprocess: executing test/test_ret_code
Test::test_poll_ret_code
  template <typename Buffer>
  template <typename T>
  template <typename T>
  template <typename Func>
  template <typename T>
template <typename... T> struct param_pack{};
template <typename F
template <typename F>
template <typename F
template <typename F
  template <typename... Args>
  template <typename... Args>
  template <typename F
template <typename F
  template<typename F
  template<typename F
  template<typename... Args>
template<typename... Args>
template<typename... Args>
template <typename... Args>
template <typename... Args>
template<typename... Args>

retcode: 0
   cpp-subprocess: executing test/test_split
a
b
c
5
   cpp-subprocess: executing test/test_subprocess
total 5624
-rw-r--r-- 1 root root     322 Oct  8 04:44 cat_fredirect.txt
-rwxr-xr-x 1 root root      91 Oct  5 17:36 env_script.sh
-rwxr-xr-x 1 root root  164048 Oct  8 04:44 test
-rw-r--r-- 1 root root     944 Oct  5 17:36 test.cc
-rwxr-xr-x 1 root root 1293920 Oct  8 04:44 test_cat
-rwxr-xr-x 1 root root    1450 Oct  5 17:36 test_cat.cc
-rwxr-xr-x 1 root root  681008 Oct  8 04:44 test_env
-rw-r--r-- 1 root root     347 Oct  5 17:36 test_env.cc
-rwxr-xr-x 1 root root  633704 Oct  8 04:44 test_err_redirection
-rw-r--r-- 1 root root     266 Oct  5 17:36 test_err_redirection.cc
-rwxr-xr-x 1 root root 1283072 Oct  8 04:44 test_ret_code
-rw-r--r-- 1 root root     776 Oct  5 17:36 test_ret_code.cc
drwxr-xr-x 3 root root      96 Oct  5 17:36 test_ret_code.dSYM
-rwxr-xr-x 1 root root  239712 Oct  8 04:44 test_split
-rw-r--r-- 1 root root     844 Oct  5 17:36 test_split.cc
-rwxr-xr-x 1 root root 1382912 Oct  8 04:44 test_subprocess
-rwxr-xr-x 1 root root    1421 Oct  5 17:36 test_subprocess.cc
-rwxr-xr-x 1 root root    1667 Oct  5 17:36 write_err.sh
-rw-r--r-- 1 root root   23040 Oct  8 04:44 write_err.txt
0
four
five

  template <typename Buffer>
  template <typename T>
  template <typename T>
  template <typename Func>
  template <typename T>
template <typename... T> struct param_pack{};
template <typename F
template <typename F>
template <typename F
template <typename F
  template <typename... Args>
  template <typename... Args>
  template <typename F
template <typename F
  template<typename F
  template<typename F
  template<typename... Args>
template<typename... Args>
template<typename... Args>
template <typename... Args>
template <typename... Args>
template<typename... Args>

  template <typename... Args>
  template <typename... Args>
  template <typename F, typename... Args>
template <typename F, typename... Args>
  template<typename F, typename... Args>
  template<typename F, typename... Args>
  template<typename... Args>
template<typename... Args>
template<typename... Args>
template <typename... Args>
template <typename... Args>
template<typename... Args>

total 5624
-rw-r--r-- 1 root root     322 Oct  8 04:44 cat_fredirect.txt
-rwxr-xr-x 1 root root      91 Oct  5 17:36 env_script.sh
-rwxr-xr-x 1 root root  164048 Oct  8 04:44 test
-rw-r--r-- 1 root root     944 Oct  5 17:36 test.cc
-rwxr-xr-x 1 root root 1293920 Oct  8 04:44 test_cat
-rwxr-xr-x 1 root root    1450 Oct  5 17:36 test_cat.cc
-rwxr-xr-x 1 root root  681008 Oct  8 04:44 test_env
-rw-r--r-- 1 root root     347 Oct  5 17:36 test_env.cc
-rwxr-xr-x 1 root root  633704 Oct  8 04:44 test_err_redirection
-rw-r--r-- 1 root root     266 Oct  5 17:36 test_err_redirection.cc
-rwxr-xr-x 1 root root 1283072 Oct  8 04:44 test_ret_code
-rw-r--r-- 1 root root     776 Oct  5 17:36 test_ret_code.cc
drwxr-xr-x 3 root root      96 Oct  5 17:36 test_ret_code.dSYM
-rwxr-xr-x 1 root root  239712 Oct  8 04:44 test_split
-rw-r--r-- 1 root root     844 Oct  5 17:36 test_split.cc
-rwxr-xr-x 1 root root 1382912 Oct  8 04:44 test_subprocess
-rwxr-xr-x 1 root root    1421 Oct  5 17:36 test_subprocess.cc
-rwxr-xr-x 1 root root    1667 Oct  5 17:36 write_err.sh
-rw-r--r-- 1 root root   23040 Oct  8 04:44 write_err.txt

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Sleep ended: ret code = 0
/src /src

bdangit · 2018-10-08T13:35:51Z

Awesome. One small ask, could you help to tag another release, please? :)

arun11299 reviewed Oct 6, 2018

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Replace throw with noexcept for C17 compatibility

eada8ad

C++11 started to deprecate the use of throw function identifiers. In C++17, this header no longer compiles due to the deprecation. Signed-off-by: Ben Dang <me@bdang.it>

bdangit force-pushed the support-c17 branch from 393e659 to eada8ad Compare October 8, 2018 04:48

arun11299 merged commit 899e9b9 into arun11299:master Oct 8, 2018

bdangit deleted the support-c17 branch October 8, 2018 07:50

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Replace throw with noexcept for C17 compatibility#17

Replace throw with noexcept for C17 compatibility#17
arun11299 merged 1 commit intoarun11299:masterfrom
bdangit:support-c17

bdangit commented Oct 5, 2018

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bdangit commented Oct 5, 2018

Errors due to throw

Other gcc errors discovered after fixing the throw identifiers

Testing

Environment

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Errors due to `throw`

Other gcc errors discovered after fixing the `throw` identifiers