if: emit error on too many args

Signed-off-by: Julien Danjou <julien@danjou.info>

hy/compiler.py

@@ -176,8 +176,10 @@ class HyASTCompiler(object):
             raise TypeError("if expects at least 2 arguments, got 1")
         body = self._code_branch(self.compile(body))
         orel = []
-        if len(expr) > 0:
+        if len(expr) == 1:
             orel = self._code_branch(self.compile(expr.pop(0)))
+        elif len(expr) > 1:
+            raise TypeError("if expects 2 or 3 arguments, got %d" % (len(expr) + 2))
 
         return ast.If(test=test,
                       body=body,

tests/compilers/test_ast.py

@@ -61,6 +61,15 @@ def test_ast_bad_if_1_arg():
         pass
 
 
+def test_ast_bad_if_too_much_arg():
+    "Make sure AST can't compile invalid if"
+    try:
+        hy_compile(tokenize("(if 1 2 3 4 5)"))
+        assert False
+    except TypeError:
+        pass
+
+
 def test_ast_valid_if():
     "Make sure AST can't compile invalid if"
     hy_compile(tokenize("(if foo bar)"))