bpo-40179: Fix translation of #elif in Argument Clinic

[serhiy-storchaka]

https://bugs.python.org/issue40179

[ZackerySpytz]

It seems that some of the code added in this PR does not adhere to PEP 8.

[serhiy-storchaka]

Do you mean that some line is 84 characters long? It is slightly longer that the limit recommended by PEP 8. But there are much longer lines in the surrounded code (up to 104 characters), and I prefer to keep the consistent style.

[ammaraskar]

Should we consider adding a direct test for this in clinic.test with something like:

/*[clinic input]
output push
output preset buffer
[clinic start generated code]*/

#ifdef CONDITION_A
/*[clinic input]
test_preprocessor_guarded_condition_a
[clinic start generated code]*/
#elif CONDITION_B
/*[clinic input]
test_preprocessor_guarded_elif_condition_b
[clinic start generated code]*/
#else
/*[clinic input]
test_preprocessor_guarded_else
[clinic start generated code]*/
#endif

/*[clinic input]
dump buffer
output pop
[clinic start generated code]*/

Fully expands to:

/*[clinic input]
output push
output preset buffer
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=5bff3376ee0df0b5]*/

#ifdef CONDITION_A
/*[clinic input]
test_preprocessor_guarded_condition_a
[clinic start generated code]*/

static PyObject *
test_preprocessor_guarded_condition_a_impl(PyObject *module)
/*[clinic end generated code: output=ad012af18085add6 input=8edb8706a98cda7e]*/
#elif CONDITION_B
/*[clinic input]
test_preprocessor_guarded_elif_condition_b
[clinic start generated code]*/

static PyObject *
test_preprocessor_guarded_elif_condition_b_impl(PyObject *module)
/*[clinic end generated code: output=615f2dee82b138d1 input=53777cebbf7fee32]*/
#else
/*[clinic input]
test_preprocessor_guarded_else
[clinic start generated code]*/

static PyObject *
test_preprocessor_guarded_else_impl(PyObject *module)
/*[clinic end generated code: output=13af7670aac51b12 input=6657ab31d74c29fc]*/
#endif

/*[clinic input]
dump buffer
output pop
[clinic start generated code]*/

#if defined(CONDITION_A)

PyDoc_STRVAR(test_preprocessor_guarded_condition_a__doc__,
"test_preprocessor_guarded_condition_a($module, /)\n"
"--\n"
"\n");

#define TEST_PREPROCESSOR_GUARDED_CONDITION_A_METHODDEF    \
    {"test_preprocessor_guarded_condition_a", (PyCFunction)test_preprocessor_guarded_condition_a, METH_NOARGS, test_preprocessor_guarded_condition_a__doc__},

static PyObject *
test_preprocessor_guarded_condition_a(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    return test_preprocessor_guarded_condition_a_impl(module);
}

#endif /* defined(CONDITION_A) */

#if !defined(CONDITION_A) && (CONDITION_B)

PyDoc_STRVAR(test_preprocessor_guarded_elif_condition_b__doc__,
"test_preprocessor_guarded_elif_condition_b($module, /)\n"
"--\n"
"\n");

#define TEST_PREPROCESSOR_GUARDED_ELIF_CONDITION_B_METHODDEF    \
    {"test_preprocessor_guarded_elif_condition_b", (PyCFunction)test_preprocessor_guarded_elif_condition_b, METH_NOARGS, test_preprocessor_guarded_elif_condition_b__doc__},

static PyObject *
test_preprocessor_guarded_elif_condition_b(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    return test_preprocessor_guarded_elif_condition_b_impl(module);
}

#endif /* !defined(CONDITION_A) && (CONDITION_B) */

#if !defined(CONDITION_A) && !(CONDITION_B)

PyDoc_STRVAR(test_preprocessor_guarded_else__doc__,
"test_preprocessor_guarded_else($module, /)\n"
"--\n"
"\n");

#define TEST_PREPROCESSOR_GUARDED_ELSE_METHODDEF    \
    {"test_preprocessor_guarded_else", (PyCFunction)test_preprocessor_guarded_else, METH_NOARGS, test_preprocessor_guarded_else__doc__},

static PyObject *
test_preprocessor_guarded_else(PyObject *module, PyObject *Py_UNUSED(ignored))
{
    return test_preprocessor_guarded_else_impl(module);
}

#endif /* !defined(CONDITION_A) && !(CONDITION_B) */

#ifndef TEST_PREPROCESSOR_GUARDED_CONDITION_A_METHODDEF
    #define TEST_PREPROCESSOR_GUARDED_CONDITION_A_METHODDEF
#endif /* !defined(TEST_PREPROCESSOR_GUARDED_CONDITION_A_METHODDEF) */

#ifndef TEST_PREPROCESSOR_GUARDED_ELIF_CONDITION_B_METHODDEF
    #define TEST_PREPROCESSOR_GUARDED_ELIF_CONDITION_B_METHODDEF
#endif /* !defined(TEST_PREPROCESSOR_GUARDED_ELIF_CONDITION_B_METHODDEF) */

#ifndef TEST_PREPROCESSOR_GUARDED_ELSE_METHODDEF
    #define TEST_PREPROCESSOR_GUARDED_ELSE_METHODDEF
#endif /* !defined(TEST_PREPROCESSOR_GUARDED_ELSE_METHODDEF) */
/*[clinic end generated code: output=3804bb18d454038c input=3fc80c9989d2f2e1]*/

[serhiy-storchaka]

Great idea @ammaraskar! I tried to add tests, but without output preset buffer Argument Clinic did not produce useful output. Thank you for your tests!

[serhiy-storchaka]

@larryhastings could you please take a look? It is a blocker for #19360.

[miss-islington]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.7, 3.8.
🐍🍒⛏🤖

[miss-islington]

Sorry, @serhiy-storchaka, I could not cleanly backport this to 3.8 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 12446e6a605f066d837d3a595d0a73e4f3b43b65 3.8

[miss-islington]

Sorry @serhiy-storchaka, I had trouble checking out the 3.7 backport branch.
Please backport using cherry_picker on command line.
cherry_picker 12446e6a605f066d837d3a595d0a73e4f3b43b65 3.7

[bedevere-bot]

GH-19583 is a backport of this pull request to the 3.8 branch.

[bedevere-bot]

GH-19584 is a backport of this pull request to the 3.7 branch.