rego.v1: Improving support for rules with chained bodies (open-policy…

…-agent#6374)

Fixes: open-policy-agent#6370
Signed-off-by: Johan Fylling <johan.dev@fylling.se>

ast/parser.go

@@ -724,14 +724,12 @@ func (p *Parser) parseRules() []*Rule {
 		// rule's head AST but have their location
 		// set to the rule body.
 		next.Head = rule.Head.Copy()
+		next.Head.keywords = rule.Head.keywords
 		for i := range next.Head.Args {
 			if v, ok := next.Head.Args[i].Value.(Var); ok && v.IsWildcard() {
 				next.Head.Args[i].Value = Var(p.genwildcard())
 			}
 		}
-		if hasIf {
-			next.Head.keywords = append(next.Head.keywords, tokens.If)
-		}
 		setLocRecursive(next.Head, loc)
 
 		rules = append(rules, &next)

ast/parser_test.go

@@ -1787,6 +1787,113 @@ f(x) := x {
 }`,
 			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
 		},
+		{
+			note: "rule with chained bodies, no `if`",
+			module: `package test
+import rego.v1
+p {
+	input.x == 1
+} {
+	input.x == 2
+} {
+	input.x == 3
+}`,
+			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
+		},
+		{
+			note: "rule with chained bodies, `if` on first body",
+			module: `package test
+import rego.v1
+p if {
+	input.x == 1
+} {
+	input.x == 2
+} {
+	input.x == 3
+}`,
+		},
+		{
+			note: "rule with chained bodies, `if` on second body",
+			module: `package test
+import rego.v1
+p if {
+	input.x == 1
+} if {
+	input.x == 2
+} {
+	input.x == 3
+}`,
+			expectedErrors: []string{`5:3: rego_parse_error: unexpected if keyword
+	} if {
+	  ^`},
+		},
+		{
+			note: "rule with chained bodies, `if` on third/last body",
+			module: `package test
+import rego.v1
+p if {
+	input.x == 1
+} {
+	input.x == 2
+} if {
+	input.x == 3
+}`,
+			expectedErrors: []string{`7:3: rego_parse_error: unexpected if keyword
+	} if {
+	  ^`},
+		},
+		{
+			note: "rule with chained bodies, `if` and `contains` on first body",
+			module: `package test
+import rego.v1
+p contains x if {
+	x == 1
+} {
+	x == 2
+} {
+	x == 3
+}`,
+		},
+		{
+			note: "function with chained bodies, no `if`",
+			module: `package test
+import rego.v1
+f(x) {
+	x == 1
+} {
+	x == 2
+} {
+	x == 3
+}`,
+			expectedErrors: []string{"rego_parse_error: `if` keyword is required before rule body"},
+		},
+		{
+			note: "function with chained bodies, `if` on first body",
+			module: `package test
+import rego.v1
+f(x) if {
+	x == 1
+} {
+	x == 2
+} {
+	x == 3
+}`,
+		},
+		{
+			note: "function with chained bodies, `if` on other than first body",
+			module: `package test
+import rego.v1
+f(x) if {
+	x == 1
+} if {
+	x == 2
+} {
+	x == 3
+}`,
+			expectedErrors: []string{`5:3: rego_parse_error: unexpected if keyword
+	} if {
+	  ^`},
+		},
 	}
 
 	for _, tc := range tests {