--- a/mercurial/registrar.py	Mon Mar 19 20:39:06 2018 +0900
+++ b/mercurial/registrar.py	Sun Mar 18 15:14:58 2018 +0900
@@ -324,7 +324,7 @@
 
         templatefilter = registrar.templatefilter()
 
-        @templatefilter('myfilter')
+        @templatefilter('myfilter', intype=bytes)
         def myfilterfunc(text):
             '''Explanation of this template filter ....
             '''
@@ -332,6 +332,9 @@
 
     The first string argument is used also in online help.
 
+    Optional argument 'intype' defines the type of the input argument,
+    which should be (bytes, int, or None for any.)
+
     'templatefilter' instance in example above can be used to
     decorate multiple functions.
 
@@ -342,6 +345,9 @@
     Otherwise, explicit 'templatefilters.loadkeyword()' is needed.
     """
 
+    def _extrasetup(self, name, func, intype=None):
+        func._intype = intype
+
 class templatefunc(_templateregistrarbase):
     """Decorator to register template function
 

--- a/mercurial/templatefilters.py	Mon Mar 19 20:39:06 2018 +0900
+++ b/mercurial/templatefilters.py	Sun Mar 18 15:14:58 2018 +0900
@@ -354,12 +354,12 @@
 def stringescape(text):
     return stringutil.escapestr(text)
 
-@templatefilter('stringify')
+@templatefilter('stringify', intype=bytes)
 def stringify(thing):
     """Any type. Turns the value into text by converting values into
     text and concatenating them.
     """
-    return templateutil.stringify(thing)
+    return thing  # coerced by the intype
 
 @templatefilter('stripdir')
 def stripdir(text):

--- a/mercurial/templateutil.py	Mon Mar 19 20:39:06 2018 +0900
+++ b/mercurial/templateutil.py	Sun Mar 18 15:14:58 2018 +0900
@@ -342,6 +342,7 @@
     return stringify(thing)
 
 _unwrapfuncbytype = {
+    None: _unwrapvalue,
     bytes: stringify,
     int: unwrapinteger,
 }
@@ -400,8 +401,9 @@
 
 def runfilter(context, mapping, data):
     arg, filt = data
-    thing = evalfuncarg(context, mapping, arg)
+    thing = evalrawexp(context, mapping, arg)
     try:
+        thing = unwrapastype(thing, getattr(filt, '_intype', None))
         return filt(thing)
     except (ValueError, AttributeError, TypeError):
         sym = findsymbolicname(arg)