FIX: Declare cimported ctuples (GH-1427) (GH-3271)

Closes #1427 

Cython/Compiler/ModuleNode.py

@@ -575,15 +575,17 @@ class ModuleNode(Nodes.Node, Nodes.BlockNode):
         for entry in vtabslot_list:
             self.generate_objstruct_predeclaration(entry.type, code)
         vtabslot_entries = set(vtabslot_list)
+        ctuple_names = set()
         for module in modules:
             definition = module is env
-            if definition:
-                type_entries = module.type_entries
-            else:
-                type_entries = []
-                for entry in module.type_entries:
-                    if entry.defined_in_pxd:
+            type_entries = []
+            for entry in module.type_entries:
+                if entry.type.is_ctuple:
+                    if entry.name not in ctuple_names:
+                        ctuple_names.add(entry.name)
                         type_entries.append(entry)
+                elif definition or entry.defined_in_pxd:
+                    type_entries.append(entry)
             type_entries = [t for t in type_entries if t not in vtabslot_entries]
             self.generate_type_header_code(type_entries, code)
         for entry in vtabslot_list:

tests/compile/ctuple_cimport.pxd

+# Verify defined before function prototype
+cdef (int, int) get_a_ctuple()
+
+# Verify defined before typedef
+ctypedef (int, double) int_double
+
+# Verify typedef defined
+cdef int_double tuple_global = (1, 2.)
+
+# Verify defined before opt args
+cdef void test_opt_args((double, int) x=*)
+
+# Verify defined before class declaration
+cdef class CTupleClass:
+    cdef void get_a_ctuple(self, (double, double) x)

tests/compile/ctuple_cimport_T1427.pyx

+# ticket: 1427
+# mode: compile
+
+cimport ctuple_cimport
+
+# Verify same tuple defined in multiple pxd not redeclared
+ctypedef (int, double) int_double
+
+ctuple_cimport.get_a_ctuple()