Fix block scoped vars shadowing globals

packages/babel-plugin-transform-block-scoping/src/index.ts

@@ -202,6 +202,7 @@ function transformBlockScopedVariable(
         // a nested scope and thus we don't need to assume that it
         // may be declared (but not registered yet) in an upper one.
         blockScope.parent.hasBinding(name, { noUids: true }) ||
+        blockScope.parent.hasGlobal(name) ||
         (isProgramScope && varScope.hasGlobal(name))
       ) {
         newName = blockScope.generateUid(name);

packages/babel-plugin-transform-block-scoping/test/fixtures/general/block-not-shadow-global/input.js

@@ -0,0 +1,15 @@
+{ a; }
+{ let a; }
+
+(function () {
+  { b; }
+  { let b; }
+})();
+
+{ c = 0; }
+{ let c; }
+
+(function () {
+  { d = 0; }
+  { let d; }
+})

packages/babel-plugin-transform-block-scoping/test/fixtures/general/block-not-shadow-global/output.js

@@ -0,0 +1,28 @@
+{
+  a;
+}
+{
+  var _a;
+}
+(function () {
+  {
+    b;
+  }
+  {
+    var _b;
+  }
+})();
+{
+  c = 0;
+}
+{
+  var _c;
+}
+(function () {
+  {
+    d = 0;
+  }
+  {
+    var _d;
+  }
+});