From c1e7a82e975d97e054b769d615c36efb287d7488 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Thu, 16 Jul 2015 14:58:40 +0300
Subject: [PATCH] Add IndexError and ValueError builtins.

---
 artiq/compiler/builtins.py              | 16 +++++++++++++++-
 artiq/compiler/prelude.py               |  2 ++
 artiq/compiler/transforms/inferencer.py | 20 +++++++++++++++++++-
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/artiq/compiler/builtins.py b/artiq/compiler/builtins.py
index 4675c458c..c349baac5 100644
--- a/artiq/compiler/builtins.py
+++ b/artiq/compiler/builtins.py
@@ -43,8 +43,16 @@ class TRange(types.TMono):
         ])
 
 class TException(types.TMono):
+    def __init__(self, name="Exception"):
+        super().__init__(name)
+
+class TIndexError(types.TMono):
     def __init__(self):
-        super().__init__("Exception")
+        super().__init__("IndexError")
+
+class TValueError(types.TMono):
+    def __init__(self):
+        super().__init__("ValueError")
 
 def fn_bool():
     return types.TConstructor("bool")
@@ -61,6 +69,12 @@ def fn_list():
 def fn_Exception():
     return types.TExceptionConstructor("Exception")
 
+def fn_IndexError():
+    return types.TExceptionConstructor("IndexError")
+
+def fn_ValueError():
+    return types.TExceptionConstructor("ValueError")
+
 def fn_range():
     return types.TBuiltinFunction("range")
 
diff --git a/artiq/compiler/prelude.py b/artiq/compiler/prelude.py
index d024c2423..98432b753 100644
--- a/artiq/compiler/prelude.py
+++ b/artiq/compiler/prelude.py
@@ -13,6 +13,8 @@ def globals():
         "list":         builtins.fn_list(),
         "range":        builtins.fn_range(),
         "Exception":    builtins.fn_Exception(),
+        "IndexError":   builtins.fn_IndexError(),
+        "ValueError":   builtins.fn_ValueError(),
         "len":          builtins.fn_len(),
         "round":        builtins.fn_round(),
         "syscall":      builtins.fn_syscall(),
diff --git a/artiq/compiler/transforms/inferencer.py b/artiq/compiler/transforms/inferencer.py
index 5400da937..9e927d60f 100644
--- a/artiq/compiler/transforms/inferencer.py
+++ b/artiq/compiler/transforms/inferencer.py
@@ -432,7 +432,25 @@ class Inferencer(algorithm.Visitor):
                 node.func.loc, notes=valid_forms)
             self.engine.process(diag)
 
-        if types.is_builtin(typ, "bool"):
+        if types.is_exn_constructor(typ):
+            exns = {
+                "IndexError": builtins.TIndexError,
+                "ValueError": builtins.TValueError,
+            }
+            for exn in exns:
+                if types.is_exn_constructor(typ, exn):
+                    valid_forms = lambda: [
+                        valid_form("{exn}() -> {exn}".format(exn=exn))
+                    ]
+
+                    if len(node.args) == 0 and len(node.keywords) == 0:
+                        pass # False
+                    else:
+                        diagnose(valid_forms())
+
+                    self._unify(node.type, exns[exn](),
+                                node.loc, None)
+        elif types.is_builtin(typ, "bool"):
             valid_forms = lambda: [
                 valid_form("bool() -> bool"),
                 valid_form("bool(x:'a) -> bool")