Implement BinOp coercion rules for AugAssign.

artiq/py2llvm/typing.py

@@ -461,7 +461,7 @@ class Inferencer(algorithm.Visitor):
             self.visit(node)
             return node
 
-    def _coerce_numeric(self, return_type, left, right):
+    def _coerce_numeric(self, left, right):
         # Implements the coercion protocol.
         # See https://docs.python.org/3/library/stdtypes.html#numeric-types-int-float-complex.
         if builtins.is_float(left.type) or builtins.is_float(right.type):
@@ -474,7 +474,7 @@ class Inferencer(algorithm.Visitor):
             else:
                 typ = builtins.TInt()
         elif types.is_var(left.type) or types.is_var(right.type): # not enough info yet
-            return left, right
+            return
         else: # conflicting types
             printer = types.TypePrinter()
             note1 = diagnostic.Diagnostic("note",
@@ -489,15 +489,9 @@ class Inferencer(algorithm.Visitor):
                 left.loc, [right.loc],
                 [note1, note2])
             self.engine.process(diag)
-            return left, right
+            return
 
-        # On 1st invocation, return_type is always a type variable.
-        # On further invocations, coerce will only ever refine the type,
-        # so this should never fail.
-        return_type.unify(typ)
-
-        return self._coerce_one(typ, left, other_node=right), \
-               self._coerce_one(typ, right, other_node=left)
+        return typ, typ, typ
 
     def _order_by_pred(self, pred, left, right):
         if pred(left.type):
@@ -507,28 +501,26 @@ class Inferencer(algorithm.Visitor):
         else:
             assert False
 
-    def visit_BinOpT(self, node):
-        self.generic_visit(node)
-        if isinstance(node.op, (ast.BitAnd, ast.BitOr, ast.BitXor,
+    def _coerce_binop(self, op, left, right):
+        if isinstance(op, (ast.BitAnd, ast.BitOr, ast.BitXor,
                                 ast.LShift, ast.RShift)):
             # bitwise operators require integers
-            for operand in (node.left, node.right):
+            for operand in (left, right):
                 if not types.is_var(operand.type) and not builtins.is_int(operand.type):
                     diag = diagnostic.Diagnostic("error",
                         "expected '{op}' operand to be of integer type, not {type}",
-                        {"op": node.op.loc.source(),
+                        {"op": op.loc.source(),
                          "type": types.TypePrinter().name(operand.type)},
-                        node.op.loc, [operand.loc])
+                        op.loc, [operand.loc])
                     self.engine.process(diag)
                     return
 
-            node.left, node.right = \
-                self._coerce_numeric(node.type, node.left, node.right)
-        elif isinstance(node.op, ast.Add):
+            return self._coerce_numeric(left, right)
+        elif isinstance(op, ast.Add):
             # add works on numbers and also collections
-            if builtins.is_collection(node.left.type) or builtins.is_collection(node.right.type):
+            if builtins.is_collection(left.type) or builtins.is_collection(right.type):
                 collection, other = \
-                    self._order_by_pred(builtins.is_collection, node.left, node.right)
+                    self._order_by_pred(builtins.is_collection, left, right)
                 if types.is_tuple(collection.type):
                     pred, kind = types.is_tuple, "tuple"
                 elif builtins.is_list(collection.type):
@@ -548,32 +540,32 @@ class Inferencer(algorithm.Visitor):
                     diag = diagnostic.Diagnostic("error",
                         "expected every '+' operand to be a {kind} in this context",
                         {"kind": kind},
-                        node.op.loc, [other.loc, collection.loc],
+                        op.loc, [other.loc, collection.loc],
                         [note1, note2])
                     self.engine.process(diag)
                     return
 
                 if types.is_tuple(collection.type):
                     # should never fail
-                    node.type.unify(types.TTuple(node.left.type.find().elts +
-                                                    node.right.type.find().elts))
+                    return types.TTuple(left.type.find().elts +
+                                        right.type.find().elts), left.type, right.type
                 elif builtins.is_list(collection.type):
-                    self._unify(node.left.type, node.right.type,
-                                node.left.loc, node.right.loc)
-                    node.type.unify(node.left.type) # should never fail
+                    self._unify(left.type, right.type,
+                                left.loc, right.loc)
+                    return left.type, left.type, right.type
             else:
-                node.left, node.right = \
-                    self._coerce_numeric(node.type, node.left, node.right)
-        elif isinstance(node.op, ast.Mult):
+                return self._coerce_numeric(left, right)
+        elif isinstance(op, ast.Mult):
             # mult works on numbers and also number & collection
-            if types.is_tuple(node.left.type) or types.is_tuple(node.right.type):
-                tuple_, other = self._order_by_pred(types.is_tuple, node.left, node.right)
+            if types.is_tuple(left.type) or types.is_tuple(right.type):
+                tuple_, other = self._order_by_pred(types.is_tuple, left, right)
                 diag = diagnostic.Diagnostic("error",
                     "py2llvm does not support passing tuples to '*'", {},
-                    node.op.loc, [tuple_.loc])
+                    op.loc, [tuple_.loc])
                 self.engine.process(diag)
-            elif builtins.is_list(node.left.type) or builtins.is_list(node.right.type):
-                list_, other = self._order_by_pred(builtins.is_list, node.left, node.right)
+                return
+            elif builtins.is_list(left.type) or builtins.is_list(right.type):
+                list_, other = self._order_by_pred(builtins.is_list, left, right)
                 if not builtins.is_int(other.type):
                     printer = types.TypePrinter()
                     note1 = diagnostic.Diagnostic("note",
@@ -586,25 +578,33 @@ class Inferencer(algorithm.Visitor):
                         other.loc)
                     diag = diagnostic.Diagnostic("error",
                         "expected '*' operands to be a list and an integer in this context", {},
-                        node.op.loc, [list_.loc, other.loc],
+                        op.loc, [list_.loc, other.loc],
                         [note1, note2])
                     self.engine.process(diag)
                     return
-                node.type.unify(list_.type)
+
+                return list_.type, left.type, right.type
             else:
-                node.left, node.right = \
-                    self._coerce_numeric(node.type, node.left, node.right)
-        elif isinstance(node.op, (ast.Div, ast.FloorDiv, ast.Mod, ast.Pow, ast.Sub)):
+                return self._coerce_numeric(left, right)
+        elif isinstance(op, (ast.Div, ast.FloorDiv, ast.Mod, ast.Pow, ast.Sub)):
             # numeric operators work on any kind of number
-            node.left, node.right = \
-                self._coerce_numeric(node.type, node.left, node.right)
+            return self._coerce_numeric(left, right)
         else: # MatMult
             diag = diagnostic.Diagnostic("error",
-                "operator '{op}' is not supported", {"op": node.op.loc.source()},
-                node.op.loc)
+                "operator '{op}' is not supported", {"op": op.loc.source()},
+                op.loc)
             self.engine.process(diag)
             return
 
+    def visit_BinOpT(self, node):
+        self.generic_visit(node)
+        coerced = self._coerce_binop(node.op, node.left, node.right)
+        if coerced:
+            return_type, left_type, right_type = coerced
+            node.left  = self._coerce_one(left_type, node.left, other_node=node.right)
+            node.right = self._coerce_one(right_type, node.right, other_node=node.left)
+            node.type.unify(return_type) # should never fail
+
     def visit_Assign(self, node):
         self.generic_visit(node)
         if len(node.targets) > 1:
@@ -616,8 +616,45 @@ class Inferencer(algorithm.Visitor):
 
     def visit_AugAssign(self, node):
         self.generic_visit(node)
-        self._unify(node.target.type, node.value.type,
-                    node.target.loc, node.value.loc)
+        coerced = self._coerce_binop(node.op, node.target, node.value)
+        if coerced:
+            return_type, target_type, value_type = coerced
+
+            try:
+                node.target.type.unify(target_type)
+            except types.UnificationError as e:
+                printer = types.TypePrinter()
+                note = diagnostic.Diagnostic("note",
+                    "expression of type {typec}",
+                    {"typec": printer.name(node.value.type)},
+                    node.value.loc)
+                diag = diagnostic.Diagnostic("error",
+                    "expression of type {typea} has to be coerced to {typeb}, "
+                    "which makes assignment invalid",
+                    {"typea": printer.name(node.target.type),
+                     "typeb": printer.name(target_type)},
+                    node.op.loc, [node.target.loc], [note])
+                self.engine.process(diag)
+                return
+
+            try:
+                node.target.type.unify(return_type)
+            except types.UnificationError as e:
+                printer = types.TypePrinter()
+                note = diagnostic.Diagnostic("note",
+                    "expression of type {typec}",
+                    {"typec": printer.name(node.value.type)},
+                    node.value.loc)
+                diag = diagnostic.Diagnostic("error",
+                    "the result of this operation has type {typeb}, "
+                    "which makes assignment to a slot of type {typea} invalid",
+                    {"typea": printer.name(node.target.type),
+                     "typeb": printer.name(return_type)},
+                    node.op.loc, [node.target.loc], [note])
+                self.engine.process(diag)
+                return
+
+            node.value = self._coerce_one(value_type, node.value, other_node=node.target)
 
     def visit_For(self, node):
         old_in_loop, self.in_loop = self.in_loop, True

lit-test/py2llvm/typing/coerce.py

@@ -24,3 +24,6 @@
 
 1 + 1.0
 # CHECK-L: 1:int(width='q):float + 1.0:float:float
+
+a = []; a += [1]
+# CHECK-L: a:list(elt=int(width='r)) = []:list(elt=int(width='r)); a:list(elt=int(width='r)) += [1:int(width='r)]:list(elt=int(width='r))

lit-test/py2llvm/typing/error_coerce.py

@@ -33,3 +33,11 @@
 # CHECK-L: ${LINE:+2}: error: cannot coerce list(elt='a) to float
 # CHECK-L: ${LINE:+1}: note: expression that required coercion to float
 [] - 1.0
+
+# CHECK-L: ${LINE:+2}: error: expression of type int(width='a) has to be coerced to float, which makes assignment invalid
+# CHECK-L: ${LINE:+1}: note: expression of type float
+a = 1; a += 1.0
+
+# CHECK-L: ${LINE:+2}: error: the result of this operation has type (int(width='a), float), which makes assignment to a slot of type (int(width='a),) invalid
+# CHECK-L: ${LINE:+1}: note: expression of type (float,)
+b = (1,); b += (1.0,)