Better fused types error detection, specialized fused C++ templates

Cython/Compiler/ExprNodes.py

@@ -614,7 +614,11 @@ class ExprNode(Node):
                         src.entry.used = True
                         return self
 
+            if src_type.is_fused:
                 error(self.pos, "Type is not specific")
+            else:
+                error(self.pos, "Cannot coerce to a type that is not specialized")
+
             self.type = error_type
             return self
 

Cython/Compiler/ParseTreeTransforms.py

@@ -1726,6 +1726,28 @@ class AnalyseExpressionsTransform(CythonTransform):
         return node
 
 
+class FindInvalidUseOfFusedTypes(CythonTransform):
+
+    def visit_FuncDefNode(self, node):
+        # Errors related to use in functions with fused args will already
+        # have been detected
+        if not node.has_fused_arguments:
+            if not node.is_generator_body and node.return_type.is_fused:
+                error(node.pos, "Return type is not specified as argument type")
+            else:
+                self.visitchildren(node)
+
+        return node
+
+    def visit_ExprNode(self, node):
+        if node.type and node.type.is_fused:
+            error(node.pos, "Invalid use of fused types, type cannot be specialized")
+        else:
+            self.visitchildren(node)
+
+        return node
+
+
 class ExpandInplaceOperators(EnvTransform):
 
     def visit_InPlaceAssignmentNode(self, node):

Cython/Compiler/Pipeline.py

@@ -125,7 +125,7 @@ def create_pipeline(context, mode, exclude_classes=()):
     from Visitor import PrintTree
     from ParseTreeTransforms import WithTransform, NormalizeTree, PostParse, PxdPostParse
     from ParseTreeTransforms import ForwardDeclareTypes, AnalyseDeclarationsTransform
-    from ParseTreeTransforms import AnalyseExpressionsTransform
+    from ParseTreeTransforms import AnalyseExpressionsTransform, FindInvalidUseOfFusedTypes
     from ParseTreeTransforms import CreateClosureClasses, MarkClosureVisitor, DecoratorTransform
     from ParseTreeTransforms import InterpretCompilerDirectives, TransformBuiltinMethods
     from ParseTreeTransforms import ExpandInplaceOperators, ParallelRangeTransform
@@ -187,6 +187,7 @@ def create_pipeline(context, mode, exclude_classes=()):
         IntroduceBufferAuxiliaryVars(context),
         _check_c_declarations,
         AnalyseExpressionsTransform(context),
+        FindInvalidUseOfFusedTypes(context),
         CreateClosureClasses(context),  ## After all lookups and type inference
         ExpandInplaceOperators(context),
         OptimizeBuiltinCalls(context),  ## Necessary?

Cython/Compiler/PyrexTypes.py

@@ -50,7 +50,7 @@ class BaseType(object):
 
             for attr in subtypes:
                 list_or_subtype = getattr(self, attr)
-
+                if list_or_subtype:
                     if isinstance(list_or_subtype, BaseType):
                         list_or_subtype.get_fused_types(result, seen)
                     else:
@@ -61,7 +61,14 @@ class BaseType(object):
 
         return None
 
-    is_fused = property(get_fused_types, doc="Whether this type or any of its "
+    def _get_fused_types(self):
+        """
+        Add this indirection for the is_fused property to allow overriding
+        get_fused_types in subclasses.
+        """
+        return self.get_fused_types()
+
+    is_fused = property(_get_fused_types, doc="Whether this type or any of its "
                                              "subtypes is a fused type")
 
     def __lt__(self, other):
@@ -2864,6 +2871,8 @@ class CppClassType(CType):
     exception_check = True
     namespace = None
 
+    subtypes = ['templates']
+
     def __init__(self, name, scope, cname, base_classes, templates = None, template_type = None):
         self.name = name
         self.cname = cname

tests/errors/fused_types.pyx

@@ -57,10 +57,13 @@ _ERRORS = u"""
 fused_types.pyx:10:15: fused_type does not take keyword arguments
 fused_types.pyx:15:38: Type specified multiple times
 fused_types.pyx:17:33: Cannot fuse a fused type
+fused_types.pyx:26:4: Invalid use of fused types, type cannot be specialized
 fused_types.pyx:26:4: Not enough types specified to specialize the function, int2_t is still fused
+fused_types.pyx:27:4: Invalid use of fused types, type cannot be specialized
 fused_types.pyx:27:4: Not enough types specified to specialize the function, int2_t is still fused
 fused_types.pyx:28:16: Call with wrong number of arguments (expected 2, got 1)
 fused_types.pyx:29:16: Call with wrong number of arguments (expected 2, got 3)
+fused_types.pyx:30:4: Invalid use of fused types, type cannot be specialized
 fused_types.pyx:30:4: Keyword and starred arguments not allowed in cdef functions.
 fused_types.pyx:36:6: Invalid base type for memoryview slice: int *
 fused_types.pyx:39:0: Fused lambdas not allowed