Fix peg_generator compiler warnings under MSVC

[ammaraskar]

This fixes the following warnings:

Tools\peg_generator\peg_extension\peg_extension.c(127): warning C4477: 'printf' : format string '%4ld' requires an argument of type 'long', but variadic argument 1 has type 'Py_ssize_t'
Tools\peg_generator\peg_extension\peg_extension.c(137): warning C4113: 'PyObject *(__cdecl *)()' differs in parameter lists from 'PyCFunction'
Tools\peg_generator\peg_extension\peg_extension.c(138): warning C4113: 'PyObject *(__cdecl *)()' differs in parameter lists from 'PyCFunction'
Tools\peg_generator\peg_extension\peg_extension.c(139): warning C4113: 'PyObject *(__cdecl *)()' differs in parameter lists from 'PyCFunction'

Parser\tokenizer.c(35): warning C4273: 'PyOS_Readline': inconsistent dll linkage
include\pythonrun.h(184): note: see previous definition of 'PyOS_Readline'

The changes to peg_extension.c are pretty simple.

---

For the tokenizer.c change, looking through the blame, it looks like PyOS_Readline was extern'd so it could be included in both the old C pgen executable and the interpreter:

• When it was added: f4b1a64
• Before Pablo removed the C version of pgen in bpo-35808, we still used to link with tokenizer.o and myreadline.o: https://github.com/python/cpython/blob/3.7/Makefile.pre.in#L311)

Unfortunately right now this causes a warning due when building the peg_generator module since it uses tokenizer.c as a source file. This causes a mismatch between the extern'd PyOS_Readline and the PyAPI_FUNC'd version of the functions.

Since we're building an extension, this causes pyport.h to set the function as a __declspec(dllimport) which doesn't match the extern definition without the import declaration. See the page on the warning for more details: https://docs.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4273?view=vs-2019

As far as I know, the only supported way of using tokenizer.c is with a Python runtime (since the #ifndef PGEN guards were removed) so this extern should be safe to remove now.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @pablogsal for commit 7f546f8 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[pablogsal]

LGTM

[miss-islington]

Thanks @ammaraskar for the PR, and @pablogsal for merging it 🌮🎉.. I'm working now to backport this PR to: 3.9.
🐍🍒⛏🤖

[bedevere-bot]

GH-20408 is a backport of this pull request to the 3.9 branch.

[pablogsal]

Thank you very much for fixing these and for the detailed analysis 🚀