ast: Improve error reporting for attachment error

Previously the parser would panic if the annotation was unattached because no scope can be unattached currently. Signed-off-by: Torin Sandall <[email protected]>
open-policy-agent · Apr 27, 2021 · 6f502bf · 6f502bf
1 parent 6d56317
commit 6f502bf
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Showing 2 changed files with 19 additions and 7 deletions.
diff --git a/ast/parser_ext.go b/ast/parser_ext.go
@@ -691,19 +691,23 @@ func validateAnnotationScopeAttachment(a *Annotations) *Error {
 		if _, ok := a.node.(*Rule); ok {
 			return nil
 		}
-		return newScopeAttachmentErr(a)
+		return newScopeAttachmentErr(a, "rule")
 	case annotationScopePackage, annotationScopeSubpackages:
 		if _, ok := a.node.(*Package); ok {
 			return nil
 		}
-		return newScopeAttachmentErr(a)
+		return newScopeAttachmentErr(a, "package")
 	}
 
 	return NewError(ParseErr, a.Loc(), "invalid annotation scope '%v'", a.Scope)
 }
 
-func newScopeAttachmentErr(a *Annotations) *Error {
-	return NewError(ParseErr, a.Loc(), "annotation scope '%v' cannot be applied to %v statement", a.Scope, TypeName(a.node))
+func newScopeAttachmentErr(a *Annotations, want string) *Error {
+	var have string
+	if a.node != nil {
+		have = fmt.Sprintf(" (have %v)", TypeName(a.node))
+	}
+	return NewError(ParseErr, a.Loc(), "annotation scope '%v' must be applied to %v%v", a.Scope, want, have)
 }
 
 func setRuleModule(rule *Rule, module *Module) {

diff --git a/ast/parser_test.go b/ast/parser_test.go
@@ -3061,23 +3061,31 @@ package test
 
 p := 7`,
 			expNumComments: 2,
-			expError:       "annotation scope 'rule' cannot be applied to package statement",
+			expError:       "test.rego:2: rego_parse_error: annotation scope 'rule' must be applied to rule (have package)",
 		},
 		{
 			note: "Scope attachment error: document on import",
 			module: `package test
 # METADATA
 # scope: document
 import data.foo.bar`,
-			expError: "test.rego:2: rego_parse_error: annotation scope 'document' cannot be applied to import statement",
+			expError: "test.rego:2: rego_parse_error: annotation scope 'document' must be applied to rule (have import)",
+		},
+		{
+			note: "Scope attachment error: unattached",
+			module: `package test
+
+# METADATA
+# scope: package`,
+			expError: "test.rego:3: rego_parse_error: annotation scope 'package' must be applied to package",
 		},
 		{
 			note: "Scope attachment error: package on non-package",
 			module: `package test
 # METADATA
 # scope: package
 import data.foo`,
-			expError: "test.rego:2: rego_parse_error: annotation scope 'package' cannot be applied to import statement",
+			expError: "test.rego:2: rego_parse_error: annotation scope 'package' must be applied to package (have import)",
 		},
 		{
 			note: "Inline schema definition",