JS: Special-case alert message for type annotations

Author: asgerf

javascript/ql/src/LanguageFeatures/NonLinearPattern.ql

@@ -37,12 +37,25 @@ class RootDestructuringPattern extends BindingPattern {
     hasConflictingBindings(name) and
     result = min(VarDecl decl | decl = getABindingVarRef() and decl.getName() = name | decl order by decl.getLocation().getStartLine(), decl.getLocation().getStartColumn())
   }
+
+  /** Holds if variables in this pattern may resemble type annotations. */
+  predicate resemblesTypeAnnotation() {
+    hasConflictingBindings(_) and // Restrict size of predicate.
+    this instanceof Parameter and
+    this instanceof ObjectPattern and
+    not exists(getTypeAnnotation()) and
+    getFile().getFileType().isTypeScript()
+  }
 }
 
-from RootDestructuringPattern p, string n, VarDecl v, VarDecl w
+from RootDestructuringPattern p, string n, VarDecl v, VarDecl w, string message
 where
   v = p.getFirstClobberedVarDecl(n) and
   w = p.getABindingVarRef() and
   w.getName() = n and
-  v != w
-select w, "Repeated binding of pattern variable '" + n + "' previously bound $@.", v, "here"
+  v != w and
+  if p.resemblesTypeAnnotation() then
+    message = "The pattern variable '" + n + "' appears to be a type, but is a variable previously bound $@."
+  else
+    message = "Repeated binding of pattern variable '" + n + "' previously bound $@."
+select w, message, v, "here"

javascript/ql/test/query-tests/LanguageFeatures/NonLinearPattern/NonLinearPattern.expected

@@ -1,9 +1,10 @@
 | ts-test.ts:3:13:3:13 | x | Repeated binding of pattern variable 'x' previously bound $@. | ts-test.ts:3:10:3:10 | x | here |
 | ts-test.ts:8:16:8:16 | x | Repeated binding of pattern variable 'x' previously bound $@. | ts-test.ts:8:10:8:10 | x | here |
 | ts-test.ts:11:10:11:10 | x | Repeated binding of pattern variable 'x' previously bound $@. | ts-test.ts:11:7:11:7 | x | here |
-| ts-test.ts:21:8:21:13 | string | Repeated binding of pattern variable 'string' previously bound $@. | ts-test.ts:20:8:20:13 | string | here |
+| ts-test.ts:21:8:21:13 | string | The pattern variable 'string' appears to be a type, but is a variable previously bound $@. | ts-test.ts:20:8:20:13 | string | here |
 | ts-test.ts:32:16:32:16 | x | Repeated binding of pattern variable 'x' previously bound $@. | ts-test.ts:30:12:30:12 | x | here |
 | ts-test.ts:34:20:34:20 | x | Repeated binding of pattern variable 'x' previously bound $@. | ts-test.ts:30:12:30:12 | x | here |
+| ts-test.ts:40:27:40:32 | string | Repeated binding of pattern variable 'string' previously bound $@. | ts-test.ts:40:16:40:21 | string | here |
 | tst.js:3:13:3:13 | x | Repeated binding of pattern variable 'x' previously bound $@. | tst.js:3:10:3:10 | x | here |
 | tst.js:8:16:8:16 | x | Repeated binding of pattern variable 'x' previously bound $@. | tst.js:8:10:8:10 | x | here |
 | tst.js:11:10:11:10 | x | Repeated binding of pattern variable 'x' previously bound $@. | tst.js:11:7:11:7 | x | here |

javascript/ql/test/query-tests/LanguageFeatures/NonLinearPattern/ts-test.ts

@@ -36,3 +36,6 @@ function blah(arg) {
         }
     } = arg;
 }
+
+function h({x: string, y: string}: any) {  // NOT OK
+}