Validate context expressions

languageservice/src/expression-validation/visitor.test.ts

@@ -56,6 +56,25 @@ describe("validation visitor", () => {
     ]);
   });
 
+  it("invalid context access as index", () => {
+    expect(useVisitor("github[github.foo]", ["github"])).toEqual([
+      {
+        message: "Context access might be invalid: foo",
+        range: {
+          end: {
+            column: 17,
+            line: 0
+          },
+          start: {
+            column: 7,
+            line: 0
+          }
+        },
+        severity: "warning"
+      }
+    ]);
+  });
+
   it("invalid nested context access", () => {
     expect(useVisitor("github.repo.name", ["github"])).toEqual([
       {

languageservice/src/expression-validation/visitor.ts

@@ -1,4 +1,4 @@
-import {DescriptionDictionary} from "@actions/expressions/.";
+import {DescriptionDictionary} from "@actions/expressions";
 import {
   Binary,
   ContextAccess,
@@ -76,7 +76,8 @@ export class ValidationVisitor implements ExprVisitor<void> {
     while (i) {
       if (i instanceof IndexAccess) {
         if (!(i.index instanceof Literal)) {
-          // Cannot validate
+          // Not a literal, validate independently
+          this._validate(i.index);
           return;
         }
         s.push(i.index.literal);