diff --git a/mercurial/templatefuncs.py b/mercurial/templatefuncs.py --- a/mercurial/templatefuncs.py +++ b/mercurial/templatefuncs.py @@ -113,6 +113,13 @@ def extdata(context, mapping, args): raise error.ParseError(_('extdata expects one argument')) source = evalstring(context, mapping, args['source']) + if not source: + sym = templateutil.findsymbolicname(args['source']) + if sym: + raise error.ParseError(_('empty data source specified'), + hint=_("did you mean extdata('%s')?") % sym) + else: + raise error.ParseError(_('empty data source specified')) cache = context.resource(mapping, 'cache').setdefault('extdata', {}) ctx = context.resource(mapping, 'ctx') if source in cache: diff --git a/tests/test-extdata.t b/tests/test-extdata.t --- a/tests/test-extdata.t +++ b/tests/test-extdata.t @@ -82,6 +82,13 @@ test bad extdata() template source $ hg log -T "{extdata('unknown')}\n" abort: unknown extdata source 'unknown' [255] + $ hg log -T "{extdata(unknown)}\n" + hg: parse error: empty data source specified + (did you mean extdata('unknown')?) + [255] + $ hg log -T "{extdata('{unknown}')}\n" + hg: parse error: empty data source specified + [255] we don't fix up relative file URLs, but we do run shell commands in repo root