Merge pull request #4028 from asger-semmle/js/scope-manager-npe

Approved by max-schaefer

Author: codeql-ci

javascript/extractor/src/com/semmle/js/extractor/ScopeManager.java

@@ -622,7 +622,9 @@ public Void visit(FunctionExpression nd, Void c) {
               nd.getReturnType().accept(this, c);
             }
             for (ITypeExpression paramType : nd.getParameterTypes()) {
-              paramType.accept(this, c);
+              if (paramType != null) {
+                paramType.accept(this, c);
+              }
             }
             // note: `infer` types may not occur in type parameter bounds.
             return null;

javascript/ql/test/library-tests/TypeScript/RegressionTests/PartialFunctionArgs/Test.expected

@@ -0,0 +1 @@
+| tst.ts:1:1:1:61 | type Fo ... : never | tst.ts:1:15:1:61 | T exten ... : never |

javascript/ql/test/library-tests/TypeScript/RegressionTests/PartialFunctionArgs/Test.ql

@@ -0,0 +1,4 @@
+import javascript
+
+from TypeAliasDeclaration decl
+select decl, decl.getDefinition()

javascript/ql/test/library-tests/TypeScript/RegressionTests/PartialFunctionArgs/tsconfig.json

@@ -0,0 +1,3 @@
+{
+    "include": ["."]
+}

javascript/ql/test/library-tests/TypeScript/RegressionTests/PartialFunctionArgs/tst.ts

@@ -0,0 +1 @@
+type Foo<T> = T extends (a, ...b: infer U) => any ? U : never