From ca585be25e2df6291ac6fd747c1152187d2669d6 Mon Sep 17 00:00:00 2001
From: alex-xnor <alex@xnor.ai>
Date: Wed, 16 Oct 2019 11:48:51 -0700
Subject: [PATCH] Make sure not to emit duplicate typedefs for fused nodes
 (GH-3112)

---
 Cython/Compiler/FusedNode.py            | 14 +++++----
 tests/compile/fused_redeclare_T3111.pyx | 39 +++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 6 deletions(-)
 create mode 100644 tests/compile/fused_redeclare_T3111.pyx

diff --git a/Cython/Compiler/FusedNode.py b/Cython/Compiler/FusedNode.py
index 011290e954a..87a9ae2b343 100644
--- a/Cython/Compiler/FusedNode.py
+++ b/Cython/Compiler/FusedNode.py
@@ -507,20 +507,22 @@ def _buffer_declarations(self, pyx_code, decl_code, all_buffer_types, pythran_ty
                 ndarray = __Pyx_ImportNumPyArrayTypeIfAvailable()
             """)
 
+        seen_typedefs = set()
         seen_int_dtypes = set()
         for buffer_type in all_buffer_types:
             dtype = buffer_type.dtype
+            dtype_name = self._dtype_name(dtype)
             if dtype.is_typedef:
-                 #decl_code.putln("ctypedef %s %s" % (dtype.resolve(),
-                 #                                    self._dtype_name(dtype)))
-                decl_code.putln('ctypedef %s %s "%s"' % (dtype.resolve(),
-                                                         self._dtype_name(dtype),
-                                                         dtype.empty_declaration_code()))
+                if dtype_name not in seen_typedefs:
+                    seen_typedefs.add(dtype_name)
+                    decl_code.putln(
+                        'ctypedef %s %s "%s"' % (dtype.resolve(), dtype_name,
+                                                 dtype.empty_declaration_code()))
 
             if buffer_type.dtype.is_int:
                 if str(dtype) not in seen_int_dtypes:
                     seen_int_dtypes.add(str(dtype))
-                    pyx_code.context.update(dtype_name=self._dtype_name(dtype),
+                    pyx_code.context.update(dtype_name=dtype_name,
                                             dtype_type=self._dtype_type(dtype))
                     pyx_code.local_variable_declarations.put_chunk(
                         u"""
diff --git a/tests/compile/fused_redeclare_T3111.pyx b/tests/compile/fused_redeclare_T3111.pyx
new file mode 100644
index 00000000000..3dfed9f38b0
--- /dev/null
+++ b/tests/compile/fused_redeclare_T3111.pyx
@@ -0,0 +1,39 @@
+# ticket: 3111
+# mode: compile
+# tag: warnings
+
+ctypedef unsigned char npy_uint8
+ctypedef unsigned short npy_uint16
+
+
+ctypedef fused dtype_t:
+    npy_uint8
+
+ctypedef fused dtype_t_out:
+    npy_uint8
+    npy_uint16
+
+
+def foo(dtype_t[:] a, dtype_t_out[:, :] b):
+    pass
+
+
+# The primary thing we're trying to test here is the _absence_ of the warning
+# "__pyxutil:16:4: '___pyx_npy_uint8' redeclared".  The remaining warnings are
+# unrelated to this test.
+_WARNINGS = """
+22:10: 'cpdef_method' redeclared
+33:10: 'cpdef_cname_method' redeclared
+446:72: Argument evaluation order in C function call is undefined and may not be as expected
+446:72: Argument evaluation order in C function call is undefined and may not be as expected
+749:34: Argument evaluation order in C function call is undefined and may not be as expected
+749:34: Argument evaluation order in C function call is undefined and may not be as expected
+943:27: Ambiguous exception value, same as default return value: 0
+943:27: Ambiguous exception value, same as default return value: 0
+974:29: Ambiguous exception value, same as default return value: 0
+974:29: Ambiguous exception value, same as default return value: 0
+1002:46: Ambiguous exception value, same as default return value: 0
+1002:46: Ambiguous exception value, same as default return value: 0
+1092:29: Ambiguous exception value, same as default return value: 0
+1092:29: Ambiguous exception value, same as default return value: 0
+"""