From faaf189961cf9850bc4b246e14f0bf5f8ce503a5 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Sat, 13 Jun 2015 13:50:56 +0300
Subject: [PATCH] Add support for Attribute.

---
 artiq/py2llvm/builtins.py              |  2 ++
 artiq/py2llvm/types.py                 |  4 +--
 artiq/py2llvm/typing.py                | 35 ++++++++++++++++++++------
 lit-test/py2llvm/typing/error_unify.py |  3 +++
 4 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/artiq/py2llvm/builtins.py b/artiq/py2llvm/builtins.py
index c547ef374..84229cc6c 100644
--- a/artiq/py2llvm/builtins.py
+++ b/artiq/py2llvm/builtins.py
@@ -26,6 +26,8 @@ class TFloat(types.TMono):
 class TTuple(types.Type):
     """A tuple type."""
 
+    attributes = {}
+
     def __init__(self, elts=[]):
         self.elts = elts
 
diff --git a/artiq/py2llvm/types.py b/artiq/py2llvm/types.py
index 2397ea61f..cce235ed8 100644
--- a/artiq/py2llvm/types.py
+++ b/artiq/py2llvm/types.py
@@ -37,8 +37,6 @@ class TVar(Type):
     folded into this class.
     """
 
-    attributes = ()
-
     def __init__(self):
         self.parent = self
 
@@ -71,6 +69,8 @@ class TVar(Type):
 class TMono(Type):
     """A monomorphic type, possibly parametric."""
 
+    attributes = {}
+
     def __init__(self, name, params={}):
         self.name, self.params = name, params
 
diff --git a/artiq/py2llvm/typing.py b/artiq/py2llvm/typing.py
index 33e8c4dc2..a35b763f6 100644
--- a/artiq/py2llvm/typing.py
+++ b/artiq/py2llvm/typing.py
@@ -224,6 +224,13 @@ class ASTTypedRewriter(algorithm.Transformer):
                               elts=node.elts, ctx=node.ctx, loc=node.loc)
         return self.visit(node)
 
+    def visit_Attribute(self, node):
+        node = self.generic_visit(node)
+        node = asttyped.AttributeT(type=types.TVar(),
+                                   value=node.value, attr=node.attr, ctx=node.ctx,
+                                   dot_loc=node.dot_loc, attr_loc=node.attr_loc, loc=node.loc)
+        return self.visit(node)
+
     def visit_Subscript(self, node):
         node = self.generic_visit(node)
         node = asttyped.SubscriptT(type=types.TVar(),
@@ -231,13 +238,6 @@ class ASTTypedRewriter(algorithm.Transformer):
                                    loc=node.loc)
         return self.visit(node)
 
-    def visit_IfExp(self, node):
-        node = self.generic_visit(node)
-        node = asttyped.IfExpT(type=types.TVar(),
-                               test=node.test, body=node.body, orelse=node.orelse,
-                               if_loc=node.if_loc, else_loc=node.else_loc, loc=node.loc)
-        return self.visit(node)
-
     def visit_BoolOp(self, node):
         node = self.generic_visit(node)
         node = asttyped.BoolOpT(type=types.TVar(),
@@ -266,6 +266,13 @@ class ASTTypedRewriter(algorithm.Transformer):
                                  loc=node.loc)
         return self.visit(node)
 
+    def visit_IfExp(self, node):
+        node = self.generic_visit(node)
+        node = asttyped.IfExpT(type=types.TVar(),
+                               test=node.test, body=node.body, orelse=node.orelse,
+                               if_loc=node.if_loc, else_loc=node.else_loc, loc=node.loc)
+        return self.visit(node)
+
     # Unsupported visitors
     #
     def visit_unsupported(self, node):
@@ -275,7 +282,6 @@ class ASTTypedRewriter(algorithm.Transformer):
         self.engine.process(diag)
 
     # expr
-    visit_Attribute = visit_unsupported
     visit_BinOp = visit_unsupported
     visit_Call = visit_unsupported
     visit_Compare = visit_unsupported
@@ -373,6 +379,19 @@ class Inferencer(algorithm.Visitor):
             self._unify(node.type["elt"], elt.type,
                         node.loc, elt.loc, self._makenotes_elts(node.elts, "a list element"))
 
+    def visit_AttributeT(self, node):
+        object_type = node.value.type.find()
+        if not types.is_var(object_type):
+            if node.attr in object_type.attributes:
+                # assumes no free type variables in .attributes
+                node.type = object_type.attributes[node.attr]
+            else:
+                diag = diagnostic.Diagnostic("error",
+                    "type {type} does not have an attribute '{attr}'",
+                    {"type": types.TypePrinter().name(object_type), "attr": node.attr},
+                    node.attr_loc, [node.value.loc])
+                self.engine.process(diag)
+
     def visit_SubscriptT(self, node):
         # TODO: support more than just lists
         self._unify(builtins.TList(node.type), node.value.type,
diff --git a/lit-test/py2llvm/typing/error_unify.py b/lit-test/py2llvm/typing/error_unify.py
index 73641b8c6..d268837e1 100644
--- a/lit-test/py2llvm/typing/error_unify.py
+++ b/lit-test/py2llvm/typing/error_unify.py
@@ -22,3 +22,6 @@ a = b
 
 # CHECK-L: ${LINE:+1}: error: expected ~ operand to be of integer type, not float
 ~1.0
+
+# CHECK-L: ${LINE:+1}: error: type int(width='a) does not have an attribute 'x'
+(1).x