OPA fails to load bundle when optimizations are enabled

[torsrex]

OPA fails to load bundle when optimizations are enabled.

Expected Behavior

First running opa build -O=1 . -e rules/main/allowed and then opa run -s -b bundle.tar.gz should successfully start the server.

Actual Behavior

The exceptions shown in the image below are thrown:

Here is the corresponding un-optimized rego code:

bearer_token(auth_header) = t {
	startswith(auth_header, "Bearer ")
	parts := split(auth_header, " ")
	count(parts) == 2
	t := parts[1]
}

And the optimized rego code:

bearer_token(__local15__6) = __local17__6 {
	startswith(
		__local15__6,
		"Bearer ",
	)
	split(
		__local15__6, __local57__6,
		" ",
	)
	__local16__6 = __local57__6
	count(__local16__6, __local58__6)
	__local58__6 = 2
	__local17__6 = __local16__6[1]
}

Creating the same bundle without optimizations by using opa build . -e rules/main/allowed allows the server to be started normally:

Steps to Reproduce the Problem

• OPA version:

Version: 0.34.2
Build Commit: 9f11f21
Build Timestamp: 2021-11-10T18:33:08Z
Build Hostname: Mac-1636569091949.local
Go Version: go1.17.3
WebAssembly: available

[srenatus]

Interesting, thanks for bringing this up. I wonder what's going on there.

	split(
		__local15__6, __local57__6,
		" ",
	)

should be

	split(
		__local15__6, 	" ",
		__local57__6,
	)

This could be an issue in the formatter, too, perhaps an unintended side-effect of #3864 🤔

[srenatus]

Yep definitely related to that formatter change. The formatter is used when a bundle is created to put "pretty" code into the bundle. Here, there are new variables used, and the algorithm that's determining how the arguments are supposed to be laid out breaks when it sees one "real" argument (" ") and a bunch of synthetic ones.