add support for flow declarations in scope tracking

src/babel/messages.js

@@ -7,8 +7,6 @@ export const MESSAGES = {
   classesIllegalSuperCall: "Direct super call is illegal in non-constructor, use super.$1() instead",
   classesIllegalConstructorKind: "Illegal kind for constructor method",
   scopeDuplicateDeclaration: "Duplicate declaration $1",
-  undeclaredVariable: "Reference to undeclared variable $1",
-  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
   settersInvalidParamLength: "Setters must have exactly one parameter",
   settersNoRest: "Setters aren't allowed to have a rest",
   noAssignmentsInForHead: "No assignments allowed in for-in/of head",
@@ -24,6 +22,10 @@ export const MESSAGES = {
   illegalMethodName: "Illegal method name $1",
   lostTrackNodePath: "We lost track of this nodes position, likely because the AST was directly manipulated",
 
+  undeclaredVariable: "Reference to undeclared variable $1",
+  undeclaredVariableType: "Referencing a type alias outside of a type annotation",
+  undeclaredVariableSuggestion: "Reference to undeclared variable $1 - did you mean $2?",
+
   traverseNeedsParent: "Must pass a scope and parentPath unless traversing a Program/File got a $1 node",
   traverseVerifyRootFunction: "You passed `traverse()` a function when it expected a visitor object, are you sure you didn't mean `{ enter: Function }`?",
   traverseVerifyVisitorProperty: "You passed `traverse()` a visitor object with the property $1 that has the invalid property $2",

src/babel/transformation/transformers/validation/undeclared-variable-check.js

@@ -6,6 +6,11 @@ export var metadata = {
 };
 
 export function ReferencedIdentifier(node, parent, scope, file) {
+  var binding = scope.getBinding(node.name);
+  if (binding && binding.kind === "type" && !this.parentPath.isFlow()) {
+    throw this.errorWithNode(messages.get("undeclaredVariableType", node.name), ReferenceError);
+  }
+
   if (scope.hasBinding(node.name)) return;
 
   // get the closest declaration to offer as a suggestion
@@ -34,5 +39,5 @@ export function ReferencedIdentifier(node, parent, scope, file) {
 
   //
 
-  throw file.errorWithNode(node, msg, ReferenceError);
+  throw this.errorWithNode(msg, ReferenceError);
 }

src/babel/traversal/scope/index.js

@@ -447,6 +447,8 @@ export default class Scope {
       this.registerBinding("let", path);
     } else if (t.isImportDeclaration(node) || t.isExportDeclaration(node)) {
       this.registerBinding("module", path);
+    } else if (t.isFlowDeclaration()) {
+      this.registerBinding("type", path);
     } else {
       this.registerBinding("unknown", path);
     }
@@ -494,7 +496,13 @@ export default class Scope {
 
       var local = this.getOwnBindingInfo(name);
       if (local) {
+        // don't ever let a type alias shadow a local binding
+        if (kind === "type") continue;
+
+        // same identifier so continue safely as we're likely trying to register it
+        // multiple times
         if (local.identifier === id) continue;
+
         this.checkBlockScopedCollisions(local, kind, name, id);
       }
 

src/babel/types/alias-keys.json

@@ -83,15 +83,15 @@
   "ArrayTypeAnnotation":         ["Flow"],
   "BooleanTypeAnnotation":       ["Flow", "FlowBaseAnnotation"],
   "ClassImplements":             ["Flow"],
-  "DeclareClass":                ["Flow", "FlowStatement", "Statement", "FlowDeclaration"],
-  "DeclareFunction":             ["Flow", "FlowStatement", "Statement", "FlowDeclaration"],
-  "DeclareModule":               ["Flow", "FlowStatement", "Statement", "FlowDeclaration"],
-  "DeclareVariable":             ["Flow", "FlowStatement", "Statement", "FlowDeclaration"],
+  "DeclareClass":                ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  "DeclareFunction":             ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  "DeclareModule":               ["Flow", "FlowDeclaration", "Statement"],
+  "DeclareVariable":             ["Flow", "FlowDeclaration", "Statement", "Declaration"],
   "FunctionTypeAnnotation":      ["Flow"],
   "FunctionTypeParam":           ["Flow"],
   "GenericTypeAnnotation":       ["Flow"],
   "InterfaceExtends":            ["Flow"],
-  "InterfaceDeclaration":        ["Flow", "FlowStatement", "Statement", "Declaration"],
+  "InterfaceDeclaration":        ["Flow", "FlowDeclaration", "Statement", "Declaration"],
   "IntersectionTypeAnnotation":  ["Flow"],
   "MixedTypeAnnotation":         ["Flow", "FlowBaseAnnotation"],
   "NullableTypeAnnotation":      ["Flow"],
@@ -100,7 +100,7 @@
   "StringTypeAnnotation":        ["Flow", "FlowBaseAnnotation"],
   "TupleTypeAnnotation":         ["Flow"],
   "TypeofTypeAnnotation":        ["Flow"],
-  "TypeAlias":                   ["Flow", "FlowStatement", "Statement"],
+  "TypeAlias":                   ["Flow", "FlowDeclaration", "Statement", "Declaration"],
   "TypeAnnotation":              ["Flow"],
   "TypeCastExpression":          ["Flow"],
   "TypeParameterDeclaration":    ["Flow"],

src/babel/types/retrievers.js

@@ -30,6 +30,13 @@ export function getBindingIdentifiers(node: Object): Object {
 }
 
 getBindingIdentifiers.keys = {
+  DeclareClass: "id",
+  DeclareFunction: "id",
+  DeclareModule: "id",
+  DeclareVariable: "id",
+  InterfaceDeclaration: "id",
+  TypeAlias: "id",
+
   ComprehensionExpression: "blocks",
   ComprehensionBlock: "left",