bpo-32030: Add _PyCoreConfig.module_search_paths (#4954)

_PyCoreConfig_Read() is now responsible to compute sys.path.
So sys.path is now computed before calling _Py_InitializeCore().

Changes:

* Add module_search_path, module_search_paths, executable, prefix,
  base_prefix, exec_prefix and base_exec_prefix to _PyCoreConfig.
* _PyMainInterpreterConfig_Read() now only converts wchar_t** lists
  into a Python list, it doesn't compute sys.path anymore.

Include/pystate.h

@@ -26,29 +26,24 @@ typedef PyObject* (*_PyFrameEvalFunction)(struct _frame *, int);
 
 typedef struct {
     int install_signal_handlers;  /* Install signal handlers? -1 means unset */
-    int ignore_environment; /* -E */
+
+    int ignore_environment; /* -E, Py_IgnoreEnvironmentFlag */
     int use_hash_seed;      /* PYTHONHASHSEED=x */
     unsigned long hash_seed;
-    int _disable_importlib; /* Needed by freeze_importlib */
     const char *allocator;  /* Memory allocator: _PyMem_SetupAllocators() */
-    int dev_mode;           /* -X dev */
-    int faulthandler;       /* -X faulthandler */
-    int tracemalloc;        /* -X tracemalloc=N */
-    int import_time;        /* -X importtime */
+    int dev_mode;           /* PYTHONDEVMODE, -X dev */
+    int faulthandler;       /* PYTHONFAULTHANDLER, -X faulthandler */
+    int tracemalloc;        /* PYTHONTRACEMALLOC, -X tracemalloc=N */
+    int import_time;        /* PYTHONPROFILEIMPORTTIME, -X importtime */
     int show_ref_count;     /* -X showrefcount */
     int show_alloc_count;   /* -X showalloccount */
     int dump_refs;          /* PYTHONDUMPREFS */
     int malloc_stats;       /* PYTHONMALLOCSTATS */
     int coerce_c_locale;    /* PYTHONCOERCECLOCALE, -1 means unknown */
     int coerce_c_locale_warn; /* PYTHONCOERCECLOCALE=warn */
-    int utf8_mode;          /* -X utf8 or PYTHONUTF8 environment variable,
-                               -1 means unknown */
+    int utf8_mode;          /* PYTHONUTF8, -X utf8; -1 means unknown */
 
-    wchar_t *module_search_path_env; /* PYTHONPATH environment variable */
-    wchar_t *home;          /* PYTHONHOME environment variable,
-                               see also Py_SetPythonHome(). */
     wchar_t *program_name;  /* Program name, see also Py_GetProgramName() */
-
     int argc;               /* Number of command line arguments,
                                -1 means unset */
     wchar_t **argv;         /* Command line arguments */
@@ -59,6 +54,24 @@ typedef struct {
 
     int nwarnoption;        /* Number of warnings options */
     wchar_t **warnoptions;  /* Warnings options */
+
+    /* Path configuration inputs */
+    wchar_t *module_search_path_env; /* PYTHONPATH environment variable */
+    wchar_t *home;          /* PYTHONHOME environment variable,
+                               see also Py_SetPythonHome(). */
+
+    /* Path configuration outputs */
+    int nmodule_search_path;        /* Number of sys.path paths,
+                                       -1 means unset */
+    wchar_t **module_search_paths;  /* sys.path paths */
+    wchar_t *executable;    /* sys.executable */
+    wchar_t *prefix;        /* sys.prefix */
+    wchar_t *base_prefix;   /* sys.base_prefix */
+    wchar_t *exec_prefix;   /* sys.exec_prefix */
+    wchar_t *base_exec_prefix;  /* sys.base_exec_prefix */
+
+    /* Private fields */
+    int _disable_importlib; /* Needed by freeze_importlib */
 } _PyCoreConfig;
 
 #define _PyCoreConfig_INIT \
@@ -67,7 +80,8 @@ typedef struct {
         .use_hash_seed = -1, \
         .coerce_c_locale = -1, \
         .utf8_mode = -1, \
-        .argc = -1}
+        .argc = -1, \
+        .nmodule_search_path = -1}
 /* Note: _PyCoreConfig_INIT sets other fields to 0/NULL */
 
 /* Placeholders while working on the new configuration API

PC/getpathp.c

@@ -692,6 +692,9 @@ calculate_pth_file(_PyPathConfig *config, wchar_t *prefix)
         return 0;
     }
 
+    /* FIXME, bpo-32030: Global configuration variables should not be modified
+       here, _PyPathConfig_Init() is called early in Python initialization:
+       see pymain_cmdline(). */
     return read_pth_file(config, prefix, spbuffer,
                          &Py_IsolatedFlag, &Py_NoSiteFlag);
 }