bpo-38234: Add test_init_setpath_config() to test_embed (GH-16402)

* Add test_embed.test_init_setpath_config(): test Py_SetPath()
  with PyConfig.
* test_init_setpath() and test_init_setpythonhome() no longer call
  Py_SetProgramName(), but use the default program name.
* _PyPathConfig: isolated, site_import  and base_executable
  fields are now only available on Windows.
* If executable is set explicitly in the configuration, ignore
  calculated base_executable: _PyConfig_InitPathConfig() copies
  executable to base_executable.
* Complete path config documentation.

1 files changed, 11 insertions, 4 deletions

diff --git a/Include/internal/pycore_pathconfig.h b/Include/internal/pycore_pathconfig.h
index 61b3790..b5d1144 100644
--- a/Include/internal/pycore_pathconfig.h
+++ b/Include/internal/pycore_pathconfig.h
@@ -19,6 +19,7 @@ typedef struct _PyPathConfig {
     wchar_t *program_name;
     /* Set by Py_SetPythonHome() or PYTHONHOME environment variable */
     wchar_t *home;
+#ifdef MS_WINDOWS
     /* isolated and site_import are used to set Py_IsolatedFlag and
        Py_NoSiteFlag flags on Windows in read_pth_file(). These fields
        are ignored when their value are equal to -1 (unset). */
@@ -26,12 +27,18 @@ typedef struct _PyPathConfig {
     int site_import;
     /* Set when a venv is detected */
     wchar_t *base_executable;
+#endif
 } _PyPathConfig;
 
-#define _PyPathConfig_INIT \
-    {.module_search_path = NULL, \
-     .isolated = -1, \
-     .site_import = -1}
+#ifdef MS_WINDOWS
+#  define _PyPathConfig_INIT \
+      {.module_search_path = NULL, \
+       .isolated = -1, \
+       .site_import = -1}
+#else
+#  define _PyPathConfig_INIT \
+      {.module_search_path = NULL}
+#endif
 /* Note: _PyPathConfig_INIT sets other fields to 0/NULL */
 
 PyAPI_DATA(_PyPathConfig) _Py_path_config;