Inconsistency between sjsonnet and jsonnet

[ieluw]

I happened to use jsonnet to compile Runbot's jsonnet file, which was failing but passed for sjsonnect.

The command I used:

/usr/local/Cellar/jsonnet/0.18.0/bin/jsonnet /Users/Lei.Wu/databricks/universe/ci/runbot/staging/runbot-app.jsonnet

and the error message from jsonnet is:

RUNTIME ERROR: couldn't manifest function in JSON output.
	std.jsonnet:36:49	function <anonymous>
	std.jsonnet:592:9-26	function <format_code>
	std.jsonnet:768:15-50	thunk <s>
	std.jsonnet:773:24	thunk <str>
	std.jsonnet:480:30-33
	std.jsonnet:480:19-34	thunk <w>
	std.jsonnet:476:11	thunk <w>
	std.jsonnet:472:12	function <aux>
	std.jsonnet:476:7-17	function <padding>
	std.jsonnet:480:7-38	function <pad_left>
	...
	std.jsonnet:774:11-60	function <format_codes_obj>
	std.jsonnet:774:11-60	function <format_codes_obj>
	std.jsonnet:779:7-43	function <anonymous>
	std.jsonnet:237:7-23	function <anonymous>
	/Users/Lei.Wu/databricks/universe/ci/runbot/staging/../builds/dust/utils.jsonnet.TEMPLATE:(168:5)-(188:6)	thunk <array_element>
	/Users/Lei.Wu/databricks/universe/ci/runbot/staging/../builds/dust/testshard-jobs.jsonnet.TEMPLATE:186:28-46	thunk <array_element>
	/Users/Lei.Wu/databricks/universe/ci/runbot/staging/../builds/dust/testshard-jobs.jsonnet.TEMPLATE:(185:22)-(189:6)	object <anonymous>
	/Users/Lei.Wu/databricks/universe/ci/runbot/staging/runbot-app.jsonnet.TEMPLATE:(187:5)-(203:6)	thunk <array_element>
	/Users/Lei.Wu/databricks/universe/ci/runbot/staging/runbot-app.jsonnet.TEMPLATE:(16:11)-(901:4)	object <anonymous>
	During manifestation

[szeiger]

This is a bug in the Jsonnet files. They pass a function value to a %s interpolation which is supposed to fail:

$ echo '"%1s" % function() "foo"' | jsonnet -
RUNTIME ERROR: couldn't manifest function in JSON output.
	std.jsonnet:36:49	function <anonymous>
	std.jsonnet:592:9-26	function <format_code>
	std.jsonnet:722:15-60	thunk <s>
	std.jsonnet:727:24	thunk <str>
	std.jsonnet:480:30-33
	std.jsonnet:480:19-34	thunk <w>
	std.jsonnet:476:11	thunk <w>
	std.jsonnet:472:12	function <aux>
	std.jsonnet:476:7-17	function <padding>
	std.jsonnet:480:7-38	function <pad_left>
	std.jsonnet:727:15-39	thunk <s_padded>
	std.jsonnet:733:55-63	thunk <v>
	std.jsonnet:733:11-64	function <format_codes_arr>
	std.jsonnet:733:11-64	function <format_codes_arr>
	std.jsonnet:781:7-48	function <anonymous>
	std.jsonnet:237:7-23	function <anonymous>
	<stdin>:1:1-25

Sjsonnet erroneously accepts this and silently evaluates a nullary function, just like in #120.

[szeiger]

The specification defers to Python for std.format, which shows yet another behavior:

$ python -c '"%1s" % (lambda : "foo")'

The function value is accepted and converted to a string, but it's an empty string, the function is not evaluated.

[szeiger]

The error message by jsonnet is misleading. Functions are disallowed as values in std.format but they can be manifested:

$ echo "function() 42" | jsonnet -
42