Merge pull request #1575 from Kodiologist/fix-macroexpand-nan

Fix bug in macro-expanding NaN

NEWS.rst

@@ -42,6 +42,7 @@ Bug Fixes
 * Fixed a case where `->` and `->>` duplicated an argument
 * Fixed bugs that caused `defclass` to drop statements or crash
 * Fixed a REPL crash caused by illegle unicode escape string inputs
+* `NaN` can no longer create an infinite loop during macro-expansion
 
 Misc. Improvements
 ----------------------------

hy/compiler.py

@@ -423,6 +423,8 @@ class HyASTCompiler(object):
             # pass in `atom_type`.
             atom_compiler = _compile_table[atom_type]
             arity = hy.inspect.get_arity(atom_compiler)
+            # Compliation methods may mutate the atom, so copy it first.
+            atom = copy.copy(atom)
             ret = (atom_compiler(self, atom, atom_type)
                    if arity == 3
                    else atom_compiler(self, atom))

hy/core/bootstrap.hy

@@ -41,6 +41,7 @@
                   (if ~@(cut args 2))))))
 
 (defmacro deftag [tag-name lambda-list &rest body]
+  (import hy.models)
   (if (and (not (isinstance tag-name hy.models.HySymbol))
            (not (isinstance tag-name hy.models.HyString)))
       (raise (hy.errors.HyTypeError

hy/core/language.hy

@@ -297,16 +297,12 @@ Return series of accumulated sums (or other binary function results)."
 (defn macroexpand [form]
   "Return the full macro expansion of `form`."
   (import hy.macros)
-
+  (hy.macros.macroexpand form (HyASTCompiler (calling-module-name))))
-  (setv name (calling-module-name))
-  (hy.macros.macroexpand form (HyASTCompiler name)))
 
 (defn macroexpand-1 [form]
   "Return the single step macro expansion of `form`."
   (import hy.macros)
-
+  (hy.macros.macroexpand-1 form (HyASTCompiler (calling-module-name))))
-  (setv name (calling-module-name))
-  (hy.macros.macroexpand-1 form (HyASTCompiler name)))
 
 (defn merge-with [f &rest maps]
   "Return the map of `maps` joined onto the first via the function `f`.

hy/macros.py

@@ -156,55 +156,42 @@ def make_empty_fn_copy(fn):
     return empty_fn
 
 
-def macroexpand(tree, compiler):
+def macroexpand(tree, compiler, once=False):
     """Expand the toplevel macros for the `tree`.
 
     Load the macros from the given `module_name`, then expand the (top-level)
-    macros in `tree` until it stops changing.
+    macros in `tree` until we no longer can.
 
     """
     load_macros(compiler.module_name)
-    old = None
+    while True:
-    while old != tree:
-        old = tree
-        tree = macroexpand_1(tree, compiler)
-    return tree
 
-
+        if not isinstance(tree, HyExpression) or tree == []:
-def macroexpand_1(tree, compiler):
-    """Expand the toplevel macro from `tree` once, in the context of
-    `module_name`."""
-    if isinstance(tree, HyExpression):
-        if tree == []:
             return tree
 
         fn = tree[0]
-        if fn in ("quote", "quasiquote"):
+        if fn in ("quote", "quasiquote") or not isinstance(fn, HySymbol):
+            return tree
+
+        fn = mangle(fn)
+        m = _hy_macros[compiler.module_name].get(fn) or _hy_macros[None].get(fn)
+        if not m:
             return tree
-        ntree = HyExpression(tree[:])
-        ntree.replace(tree)
 
         opts = {}
-
-        if isinstance(fn, HySymbol):
-            fn = mangle(str_type(fn))
-            m = _hy_macros[compiler.module_name].get(fn)
-            if m is None:
-                m = _hy_macros[None].get(fn)
-            if m is not None:
         if m._hy_macro_pass_compiler:
             opts['compiler'] = compiler
 
         try:
             m_copy = make_empty_fn_copy(m)
-                    m_copy(compiler.module_name, *ntree[1:], **opts)
+            m_copy(compiler.module_name, *tree[1:], **opts)
         except TypeError as e:
             msg = "expanding `" + str(tree[0]) + "': "
             msg += str(e).replace("<lambda>()", "", 1).strip()
             raise HyMacroExpansionError(tree, msg)
 
         try:
-                    obj = m(compiler.module_name, *ntree[1:], **opts)
+            obj = m(compiler.module_name, *tree[1:], **opts)
         except HyTypeError as e:
             if e.expression is None:
                 e.expression = tree
@@ -212,12 +199,18 @@ def macroexpand_1(tree, compiler):
         except Exception as e:
             msg = "expanding `" + str(tree[0]) + "': " + repr(e)
             raise HyMacroExpansionError(tree, msg)
-                replace_hy_obj(obj, tree)
+        tree = replace_hy_obj(obj, tree)
-                return obj
+
-        return ntree
+        if once:
             return tree
 
 
+def macroexpand_1(tree, compiler):
+    """Expand the toplevel macro from `tree` once, in the context of
+    `compiler`."""
+    return macroexpand(tree, compiler, once=True)
+
+
 def tag_macroexpand(tag, tree, compiler):
     """Expand the tag macro "tag" with argument `tree`."""
     load_macros(compiler.module_name)

tests/macros/test_macro_processor.py

@@ -5,7 +5,7 @@
 from hy.macros import macro, macroexpand
 from hy.lex import tokenize
 
-from hy.models import HyString, HyList, HySymbol, HyExpression
+from hy.models import HyString, HyList, HySymbol, HyExpression, HyFloat
 from hy.errors import HyMacroExpansionError
 
 from hy.compiler import HyASTCompiler
@@ -53,3 +53,12 @@ def test_preprocessor_exceptions():
     except HyMacroExpansionError as e:
         assert "_hy_anon_fn_" not in str(e)
         assert "TypeError" not in str(e)
+
+
+def test_macroexpand_nan():
+   # https://github.com/hylang/hy/issues/1574
+   import math
+   NaN = float('nan')
+   x = macroexpand(HyFloat(NaN), HyASTCompiler(__name__))
+   assert type(x) is HyFloat
+   assert math.isnan(x)

tests/native_tests/quote.hy

@@ -2,7 +2,7 @@
 ;; This file is part of Hy, which is free software licensed under the Expat
 ;; license. See the LICENSE.
 
-(import [hy [HyExpression HySymbol HyString HyBytes]])
+(import [hy [HyExpression HySymbol HyString HyBytes HyDict]])
 
 
 (defn test-quote []
@@ -43,7 +43,7 @@
   (assert (= (get q 1) (quote bar)))
   (assert (= (get q 2) (quote baz)))
   (assert (= (get q 3) (quote quux)))
-  (assert (= (type q) hy.HyDict)))
+  (assert (= (type q) HyDict)))
 
 
 (defn test-quote-expr-in-dict []