Require Python 3.4

I believe we previously agreed that the minimum supported Python
version should be 3.4.  This patch makes this change, harmonizing the
documentation (which was inconsistent about the minimum version) and
the code.

New in v2: rebased, and removed a pre-3.4 workaround from __init__.py.

Reviewed-By: Eli Zaretskii <[email protected]>
Approved-by: Kevin Buettner <[email protected]>
Acked-By: Tom de Vries <[email protected]>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31870

Author: tromey

gdb/NEWS

@@ -124,6 +124,8 @@ info threads [-gid] [-stopped] [-running] [ID]...
 
 * Python API
 
+  ** GDB no longer supports Python versions less than 3.4.
+
   ** New class gdb.Color for dealing with colors.
 
   ** New constant gdb.PARAM_COLOR represents color type of a

gdb/README

@@ -533,7 +533,7 @@ more obscure GDB `configure' options are not listed here.
      GDB scripting much more powerful than the restricted CLI
      scripting language.  If your host does not have Python installed,
      you can find it on `http://www.python.org/download/'.  The oldest
-     version of Python supported by GDB is 3.2.  The optional argument
+     version of Python supported by GDB is 3.4.  The optional argument
      PYTHON is used to find the Python headers and libraries.  It can
      be either the name of a Python executable, or the name of the
      directory in which Python is installed.

gdb/configure

@@ -28167,8 +28167,8 @@ int
 main ()
 {
 
-				    #if PY_MAJOR_VERSION != 3
-				    # error "We only support Python 3"
+				    #if PY_VERSION_HEX < 0x03040000
+				    # error "Minimum supported Python version is 3.4"
 				    #endif
 				    Py_Initialize ();
 

gdb/configure.ac

@@ -740,8 +740,8 @@ AC_DEFUN([AC_TRY_LIBPYTHON],
   found_usable_python=no
   AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include "Python.h"]],
                                  [[
-				    #if PY_MAJOR_VERSION != 3
-				    # error "We only support Python 3"
+				    #if PY_VERSION_HEX < 0x03040000
+				    # error "Minimum supported Python version is 3.4"
 				    #endif
 				    Py_Initialize ();
 				 ]])],

gdb/doc/gdb.texinfo

@@ -41466,7 +41466,7 @@ libpython is present and found at configure time.)  Python makes
 @value{GDBN} scripting much more powerful than the restricted CLI
 scripting language.  If your host does not have Python installed, you
 can find it on @url{http://www.python.org/download/}.  The oldest version
-of Python supported by GDB is 3.0.1.  The optional argument @var{python}
+of Python supported by GDB is 3.4.  The optional argument @var{python}
 is used to find the Python headers and libraries.  It can be either
 the name of a Python executable, or the name of the directory in which
 Python is installed.

gdb/python/lib/gdb/__init__.py

@@ -19,12 +19,7 @@
 import threading
 import traceback
 from contextlib import contextmanager
-
-# Python 3 moved "reload"
-if sys.version_info >= (3, 4):
-    from importlib import reload
-else:
-    from imp import reload
+from importlib import reload
 
 import _gdb
 

gdb/python/py-gdb-readline.c

@@ -29,11 +29,7 @@
 
 static char *
 gdbpy_readline_wrapper (FILE *sys_stdin, FILE *sys_stdout,
-#if PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 4
 			const char *prompt)
-#else
-			char *prompt)
-#endif
 {
   int n;
   const char *p = NULL;

gdb/python/python-internal.h

@@ -88,6 +88,8 @@
 #include <frameobject.h>
 #include "py-ref.h"
 
+static_assert (PY_VERSION_HEX >= 0x03040000);
+
 #define Py_TPFLAGS_CHECKTYPES 0
 
 /* If Python.h does not define WITH_THREAD, then the various
@@ -135,17 +137,6 @@ typedef unsigned long gdb_py_ulongest;
 
 #endif /* HAVE_LONG_LONG */
 
-#if PY_VERSION_HEX < 0x03020000
-typedef long Py_hash_t;
-#endif
-
-/* PyMem_RawMalloc appeared in Python 3.4.  For earlier versions, we can just
-   fall back to PyMem_Malloc.  */
-
-#if PY_VERSION_HEX < 0x03040000
-#define PyMem_RawMalloc PyMem_Malloc
-#endif
-
 /* A template variable holding the format character (as for
    Py_BuildValue) for a given type.  */
 template<typename T>