[binutils-gdb/gdb-8.1-branch] Fix build issue with Python 3.7

[Paul Koning <pkoning at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=863d5065467b16304f6b5c80a186e3bcc68c48a6

commit 863d5065467b16304f6b5c80a186e3bcc68c48a6
Author: Paul Koning <paul_koning@dell.com>
Date:   Sat Jun 9 13:24:34 2018 -0400

    Fix build issue with Python 3.7
    
    Originally reported in
    https://bugzilla.redhat.com/show_bug.cgi?id=1577396 -- gdb build fails
    with Python 3.7 due to references to a Python internal function whose
    declaration changed in 3.7.
    
    gdb/ChangeLog
    2018-06-09  Paul Koning  <paul_koning@dell.com>
    
    	    PR gdb/23252
    
    	    * python/python.c (do_start_initialization):
    	    Avoid call to internal Python API.
    	    (init__gdb_module): New function.

Diff:
---
 gdb/ChangeLog       |  8 ++++++++
 gdb/python/python.c | 18 +++++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7986a62..860062c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2018-06-09  Paul Koning  <paul_koning@dell.com>
+
+	PR gdb/23252
+
+	* python/python.c (do_start_initialization):
+	Avoid call to internal Python API.
+	(init__gdb_module): New function.
+
 2018-05-31  Omair Javaid  <omair.javaid@linaro.org>
 
 	PR gdb/23210
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 4844c86..bb0a46d 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1656,6 +1656,17 @@ finalize_python (void *ignore)
   restore_active_ext_lang (previous_active);
 }
 
+#ifdef IS_PY3K
+/* This is called via the PyImport_AppendInittab mechanism called
+   during initialization, to make the built-in _gdb module known to
+   Python.  */
+PyMODINIT_FUNC
+init__gdb_module (void)
+{
+  return PyModule_Create (&python_GdbModuleDef);
+}
+#endif
+
 static bool
 do_start_initialization ()
 {
@@ -1696,6 +1707,9 @@ do_start_initialization ()
      remain alive for the duration of the program's execution, so
      it is not freed after this call.  */
   Py_SetProgramName (progname_copy);
+
+  /* Define _gdb as a built-in module.  */
+  PyImport_AppendInittab ("_gdb", init__gdb_module);
 #else
   Py_SetProgramName (progname.release ());
 #endif
@@ -1705,9 +1719,7 @@ do_start_initialization ()
   PyEval_InitThreads ();
 
 #ifdef IS_PY3K
-  gdb_module = PyModule_Create (&python_GdbModuleDef);
-  /* Add _gdb module to the list of known built-in modules.  */
-  _PyImport_FixupBuiltin (gdb_module, "_gdb");
+  gdb_module = PyImport_ImportModule ("_gdb");
 #else
   gdb_module = Py_InitModule ("_gdb", python_GdbMethods);
 #endif