Fix redirection from StdError on Windows (arun11299#96)

* Fix redirection from StdError on Windows

* test: Add cross-platform test for error redirection

Author: hebasto

subprocess.hpp

@@ -1535,7 +1535,7 @@ inline void Popen::execute_process() noexcept(false)
   ZeroMemory(&siStartInfo, sizeof(STARTUPINFOW));
   siStartInfo.cb = sizeof(STARTUPINFOW);
 
-  siStartInfo.hStdError = this->stream_.g_hChildStd_OUT_Wr;
+  siStartInfo.hStdError = this->stream_.g_hChildStd_ERR_Wr;
   siStartInfo.hStdOutput = this->stream_.g_hChildStd_OUT_Wr;
   siStartInfo.hStdInput = this->stream_.g_hChildStd_IN_Rd;
 

test/CMakeLists.txt

@@ -19,3 +19,17 @@ foreach(test_file IN LISTS test_files)
         COPYONLY
     )
 endforeach()
+
+
+set(TEST_REDIRECTION_PYTHON_SCRIPT_PATH ${CMAKE_CURRENT_SOURCE_DIR}/test_redirection.py)
+configure_file(
+    ${CMAKE_CURRENT_SOURCE_DIR}/test_redirection.cc.in
+    ${CMAKE_CURRENT_BINARY_DIR}/test_redirection.cc
+    @ONLY
+)
+add_executable(test_redirection ${CMAKE_CURRENT_BINARY_DIR}/test_redirection.cc)
+target_link_libraries(test_redirection PRIVATE subprocess)
+add_test(
+    NAME test_redirection
+    COMMAND $<TARGET_FILE:test_redirection>
+)

test/test_redirection.cc.in

@@ -0,0 +1,23 @@
+#include <subprocess.hpp>
+
+#include <cstdlib>
+#include <string>
+#include <tuple>
+
+using namespace subprocess;
+
+int main() {
+  auto p = Popen("python3 @TEST_REDIRECTION_PYTHON_SCRIPT_PATH@", output{PIPE}, error{PIPE});
+  OutBuffer out_buf;
+  ErrBuffer err_buf;
+  std::tie(out_buf, err_buf) = p.communicate();
+  std::string out{out_buf.buf.data()};
+  std::string err{err_buf.buf.data()};
+
+  if (out.find("Hello message.") == std::string::npos) return EXIT_FAILURE;
+  if (err.find("Hello message.") != std::string::npos) return EXIT_FAILURE;
+  if (out.find("Error report.") != std::string::npos) return EXIT_FAILURE;
+  if (err.find("Error report.") == std::string::npos) return EXIT_FAILURE;
+
+  return EXIT_SUCCESS;
+}

test/test_redirection.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python3
+
+import sys
+
+if __name__ == "__main__":
+    print("Hello message.")
+    print("Error report.", file=sys.stderr)