patch 8.0.1451: difficult to set the python home directories properly

Problem:    It is difficult to set the python home directory properly for
            Python 2.7 and 3.5 since both use $PYTHONHOME.
Solution:   Add the 'pythonhome' and 'pythonthreehome' options. (Kazuki
            Sakamoto, closes #1266)

runtime/doc/options.txt

@@ -5965,6 +5965,20 @@ A jump table for the options with a short description can be found at |Q_op|.
 	DYNAMIC_PYTHON_DLL, which was specified at compile time.
 	Environment variables are expanded |:set_env|.
 	This option cannot be set from a |modeline| or in the |sandbox|, for
+	security reasons.
+
+						*'pythonhome'*
+'pythonhome'		string	(default "")
+			global
+			{not in Vi}
+			{only available when compiled with the |+python/dyn|
+			feature}
+	Specifies the name of the Python 2.x home directory. When 'pythonhome'
+	and the PYTHONHOME environment variable are not set, PYTHON_HOME,
+	which was specified at compile time, will be used for the Python 2.x
+	home directory.
+	Environment variables are expanded |:set_env|.
+	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
 
 						*'pythonthreedll'*
@@ -5977,6 +5991,20 @@ A jump table for the options with a short description can be found at |Q_op|.
 	DYNAMIC_PYTHON3_DLL, which was specified at compile time.
 	Environment variables are expanded |:set_env|.
 	This option cannot be set from a |modeline| or in the |sandbox|, for
+	security reasons.
+
+						*'pythonthreehome'*
+'pythonthreehome'	string	(default "")
+			global
+			{not in Vi}
+			{only available when compiled with the |+python3/dyn|
+			feature}
+	Specifies the name of the Python 3 home directory. When
+	'pythonthreehome' and the PYTHONHOME environment variable are not set,
+	PYTHON3_HOME, which was specified at compile time, will be used for
+	the Python 3 home directory.
+	Environment variables are expanded |:set_env|.
+	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
 
 						*'pyxversion'* *'pyx'*

runtime/doc/quickref.txt

@@ -839,7 +839,9 @@ Short explanation of each option:		*option-list*
 'prompt'	  'prompt'  enable prompt in Ex mode
 'pumheight'	  'ph'	    maximum height of the popup menu
 'pythondll'		    name of the Python 2 dynamic library
+'pythonhome'		    name of the Python 2 home directory
 'pythonthreedll'	    name of the Python 3 dynamic library
+'pythonthreehome'	    name of the Python 3 home directory
 'pyxversion'	  'pyx'	    Python version used for pyx* commands
 'quoteescape'	  'qe'	    escape characters used in a string
 'readonly'	  'ro'	    disallow writing the buffer

runtime/optwin.vim

@@ -1354,10 +1354,18 @@ if exists("&pythondll")
   call append("$", "pythondll\tname of the Python 2 dynamic library")
   call <SID>OptionG("pythondll", &pythondll)
 endif
+if exists("&pythonhome")
+  call append("$", "pythonhome\tname of the Python 2 home directory")
+  call <SID>OptionG("pythonhome", &pythonhome)
+endif
 if exists("&pythonthreedll")
   call append("$", "pythonthreedll\tname of the Python 3 dynamic library")
   call <SID>OptionG("pythonthreedll", &pythonthreedll)
 endif
+if exists("&pythonthreehome")
+  call append("$", "pythonthreehome\tname of the Python 3 home directory")
+  call <SID>OptionG("pythonthreehome", &pythonthreehome)
+endif
 if exists("&rubydll")
   call append("$", "rubydll\tname of the Ruby dynamic library")
   call <SID>OptionG("rubydll", &rubydll)

src/if_python.c

@@ -912,6 +912,8 @@ python_loaded(void)
 }
 #endif
 
+static char *py_home_buf = NULL;
+
     static int
 Python_Init(void)
 {
@@ -929,10 +931,15 @@ Python_Init(void)
 	}
 #endif
 
+	if (*p_pyhome != NUL)
+	{
+	    /* The string must not change later, make a copy in static memory. */
+	    py_home_buf = (char *)vim_strsave(p_pyhome);
+	    if (py_home_buf != NULL)
+		Py_SetPythonHome(py_home_buf);
+	}
 #ifdef PYTHON_HOME
-# ifdef DYNAMIC_PYTHON
+	else if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
-	if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
-# endif
 	    Py_SetPythonHome(PYTHON_HOME);
 #endif
 

src/if_python3.c

@@ -842,6 +842,8 @@ python3_loaded(void)
 }
 #endif
 
+static wchar_t *py_home_buf = NULL;
+
     static int
 Python3_Init(void)
 {
@@ -857,11 +859,18 @@ Python3_Init(void)
 
 	init_structs();
 
+	if (*p_py3home != NUL)
+	{
+	    size_t len = mbstowcs(NULL, (char *)p_py3home, 0) + 1;
 
+	    /* The string must not change later, make a copy in static memory. */
+	    py_home_buf = (wchar_t *)alloc(len * sizeof(wchar_t));
+	    if (py_home_buf != NULL && mbstowcs(
+			    py_home_buf, (char *)p_py3home, len) != (size_t)-1)
+		Py_SetPythonHome(py_home_buf);
+	}
 #ifdef PYTHON3_HOME
-# ifdef DYNAMIC_PYTHON3
+	else if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
-	if (mch_getenv((char_u *)"PYTHONHOME") == NULL)
-# endif
 	    Py_SetPythonHome(PYTHON3_HOME);
 #endif
 

src/option.c

@@ -2246,6 +2246,15 @@ static struct vimoption options[] =
 #else
 			    (char_u *)NULL, PV_NONE,
 			    {(char_u *)NULL, (char_u *)0L}
+#endif
+			    SCRIPTID_INIT},
+    {"pythonthreehome", NULL,   P_STRING|P_EXPAND|P_VI_DEF|P_SECURE,
+#if defined(FEAT_PYTHON3)
+			    (char_u *)&p_py3home, PV_NONE,
+			    {(char_u *)"", (char_u *)0L}
+#else
+			    (char_u *)NULL, PV_NONE,
+			    {(char_u *)NULL, (char_u *)0L}
 #endif
 			    SCRIPTID_INIT},
     {"pythondll",   NULL,   P_STRING|P_EXPAND|P_VI_DEF|P_SECURE,
@@ -2255,6 +2264,15 @@ static struct vimoption options[] =
 #else
 			    (char_u *)NULL, PV_NONE,
 			    {(char_u *)NULL, (char_u *)0L}
+#endif
+			    SCRIPTID_INIT},
+    {"pythonhome",  NULL,   P_STRING|P_EXPAND|P_VI_DEF|P_SECURE,
+#if defined(FEAT_PYTHON)
+			    (char_u *)&p_pyhome, PV_NONE,
+			    {(char_u *)"", (char_u *)0L}
+#else
+			    (char_u *)NULL, PV_NONE,
+			    {(char_u *)NULL, (char_u *)0L}
 #endif
 			    SCRIPTID_INIT},
     {"pyxversion", "pyx",   P_NUM|P_VI_DEF|P_SECURE,

src/option.h

@@ -696,9 +696,15 @@ EXTERN char_u	*p_perldll;	/* 'perldll' */
 #if defined(DYNAMIC_PYTHON3)
 EXTERN char_u	*p_py3dll;	/* 'pythonthreedll' */
 #endif
+#ifdef FEAT_PYTHON3
+EXTERN char_u	*p_py3home;	/* 'pythonthreehome' */
+#endif
 #if defined(DYNAMIC_PYTHON)
 EXTERN char_u	*p_pydll;	/* 'pythondll' */
 #endif
+#ifdef FEAT_PYTHON
+EXTERN char_u	*p_pyhome;	/* 'pythonhome' */
+#endif
 #if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3)
 EXTERN long	p_pyx;		/* 'pyxversion' */
 #endif

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1451,
 /**/
     1450,
 /**/