gdb/python: break dependencies between gdbpy_initialize_* functions

In a later commit in this series I will propose removing all of the
explicit gdbpy_initialize_* calls from python.c and replace these
calls with a more generic mechanism.

One of the side effects of this generic mechanism is that the order in
which the various Python sub-systems within GDB are initialized is no
longer guaranteed.

On the whole I don't think this matters, most of the sub-systems are
independent of each other, though testing did reveal a few places
where we did have dependencies, though I don't think those
dependencies were explicitly documented in a comment anywhere.

This commit removes the first dependency issue, with this and the next
commit, all of the implicit inter-sub-system dependencies will be
replaced by explicit dependencies, which will allow me to, I think,
clean up how the sub-systems are initialized.

The dependency is around the py_insn_type.  This type is setup in
gdbpy_initialize_instruction and used in gdbpy_initialize_record.
Rather than depend on the calls to these two functions being in a
particular order, in this commit I propose adding a new function
py_insn_get_insn_type.  This function will take care of setting up the
py_insn_type type and calling PyType_Ready.  This helper function can
be called from gdbpy_initialize_record and
gdbpy_initialize_instruction, and the py_insn_type will be initialized
just once.

To me this is better, the dependency is now really obvious, but also,
we no longer care in which order gdbpy_initialize_record and
gdbpy_initialize_instruction are called.

There should be no user visible changes after this commit.

1 files changed, 9 insertions, 4 deletions

diff --git a/gdb/python/py-instruction.h b/gdb/python/py-instruction.h
index 59f0893..1e60263 100644
--- a/gdb/python/py-instruction.h
+++ b/gdb/python/py-instruction.h
@@ -22,9 +22,14 @@
 
 #include "python-internal.h"
 
-/* Python type object for the abstract gdb.Instruction class.  This class
-   contains getters for four elements: "pc" (int), "data" (buffer), "decode"
-   (str) and "size" (int) that must be overridden by sub classes.  */
-extern PyTypeObject py_insn_type;
+/* Return a pointer to the py_insn_type object (see py-instruction.c), but
+   ensure that PyType_Ready has been called for the type first.  If the
+   PyType_Ready call is successful then subsequent calls to this function
+   will not call PyType_Ready, the type pointer will just be returned.
+
+   If the PyType_Ready call is not successful then nullptr is returned and
+   subsequent calls to this function will call PyType_Ready again.  */
+
+extern PyTypeObject *py_insn_get_insn_type ();
 
 #endif /* PYTHON_PY_INSTRUCTION_H */