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

Lib/test/clinic.test

@@ -3260,3 +3260,108 @@ exit:
 static PyObject *
 test_keyword_only_parameter_impl(PyObject *module, PyBytesObject *co_lnotab)
 /*[clinic end generated code: output=f25914b402039493 input=303df5046c7e37a3]*/
+
+
+/*[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]*/

Misc/NEWS.d/next/Tools-Demos/2020-04-04-19-35-22.bpo-40179.u9FH10.rst

@@ -0,0 +1 @@
+Fixed translation of ``#elif`` in Argument Clinic.

Tools/clinic/cpp.py

@@ -141,23 +141,15 @@ def pop_stack():
         token = fields[0].lower()
         condition = ' '.join(fields[1:]).strip()
 
-        if_tokens = {'if', 'ifdef', 'ifndef'}
-        all_tokens = if_tokens | {'elif', 'else', 'endif'}
-
-        if token not in all_tokens:
-            return
-
-        # cheat a little here, to reuse the implementation of if
-        if token == 'elif':
-            pop_stack()
-            token = 'if'
-
-        if token in if_tokens:
+        if token in {'if', 'ifdef', 'ifndef', 'elif'}:
             if not condition:
                 self.fail("Invalid format for #" + token + " line: no argument!")
-            if token == 'if':
+            if token in {'if', 'elif'}:
                 if not self.is_a_simple_defined(condition):
                     condition = "(" + condition + ")"
+                if token == 'elif':
+                    previous_token, previous_condition = pop_stack()
+                    self.stack.append((previous_token, negate(previous_condition)))
             else:
                 fields = condition.split()
                 if len(fields) != 1:
@@ -166,18 +158,21 @@ def pop_stack():
                 condition = 'defined(' + symbol + ')'
                 if token == 'ifndef':
                     condition = '!' + condition
+                token = 'if'
 
-            self.stack.append(("if", condition))
-            if self.verbose:
-                print(self.status())
-            return
+            self.stack.append((token, condition))
 
-        previous_token, previous_condition = pop_stack()
+        elif token == 'else':
+            previous_token, previous_condition = pop_stack()
+            self.stack.append((previous_token, negate(previous_condition)))
 
-        if token == 'else':
-            self.stack.append(('else', negate(previous_condition)))
         elif token == 'endif':
-            pass
+            while pop_stack()[0] != 'if':
+                pass
+
+        else:
+            return
+
         if self.verbose:
             print(self.status())