# HG changeset patch
# User Yuya Nishihara <yuya@tcha.org>
# Date 1471505362 -32400
# Node ID 034412ca28c3b32ee08ff5afa252aa94a223a31b
# Parent  0d5cc0c18b4eddda13d78e5af8448f2975f09f2e
templater: fix if() to not evaluate False as bool('False')

Before, False was True. This patch fixes the issue by processing True/False
transparently. The other values (including integer 0) are tested as strings
for backward compatibility, which means "if(latesttagdistance)" never be False.

Should we change the behavior of "if(0)" as well?

diff -r 0d5cc0c18b4e -r 034412ca28c3 mercurial/templater.py
--- a/mercurial/templater.py	Thu Aug 18 15:55:07 2016 +0900
+++ b/mercurial/templater.py	Thu Aug 18 16:29:22 2016 +0900
@@ -289,6 +289,15 @@
         thing = stringify(thing)
     return thing
 
+def evalboolean(context, mapping, arg):
+    func, data = arg
+    thing = func(context, mapping, data)
+    if isinstance(thing, bool):
+        return thing
+    # other objects are evaluated as strings, which means 0 is True, but
+    # empty dict/list should be False as they are expected to be ''
+    return bool(stringify(thing))
+
 def evalinteger(context, mapping, arg, err):
     v = evalfuncarg(context, mapping, arg)
     try:
@@ -560,7 +569,7 @@
         # i18n: "if" is a keyword
         raise error.ParseError(_("if expects two or three arguments"))
 
-    test = evalstring(context, mapping, args[0])
+    test = evalboolean(context, mapping, args[0])
     if test:
         yield args[1][0](context, mapping, args[1][1])
     elif len(args) == 3:
diff -r 0d5cc0c18b4e -r 034412ca28c3 tests/test-branches.t
--- a/tests/test-branches.t	Thu Aug 18 15:55:07 2016 +0900
+++ b/tests/test-branches.t	Thu Aug 18 16:29:22 2016 +0900
@@ -516,6 +516,8 @@
    }
   ]
 
+  $ hg branches --closed -T '{if(closed, "{branch}\n")}'
+  c
 
 Tests of revision branch name caching