Fix recursive functions

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-after/exec.js

@@ -0,0 +1,9 @@
+expect(() => {
+  function f(i) {
+    if (i) f(i - 1);
+    x;
+  }
+
+  let x;
+  f(3);
+}).not.toThrow();

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-after/input.js

@@ -0,0 +1,7 @@
+function f(i) {
+  if (i) f(i - 1);
+  x;
+}
+
+let x;
+f(3);

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-after/output.js

@@ -0,0 +1,7 @@
+function f(i) {
+  if (i) f(i - 1);
+  x;
+}
+
+var x;
+f(3);

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-before/exec.js

@@ -0,0 +1,9 @@
+expect(() => {
+  function f(i) {
+    if (i) f(i - 1);
+    x;
+  }
+
+  f(3);
+  let x;
+}).toThrow(ReferenceError);

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-before/input.js

@@ -0,0 +1,7 @@
+function f(i) {
+  if (i) f(i - 1);
+  x;
+}
+
+f(3);
+let x;

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-before/output.js

@@ -0,0 +1,7 @@
+function f(i) {
+  if (i) f(i - 1);
+  babelHelpers.tdz("x");
+}
+
+f(3);
+var x;

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-reference/exec.js

@@ -0,0 +1,12 @@
+expect(() => {
+  function f(i) {
+    return () => {
+      x;
+      f(i - 1);
+    };
+  }
+
+  const g = f(1);
+  let x;
+  g();
+}).not.toThrow();

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-reference/input.js

@@ -0,0 +1,10 @@
+function f(i) {
+  return () => {
+    x;
+    f(i - 1);
+  };
+}
+
+const g = f(1);
+let x;
+g();

packages/babel-plugin-transform-block-scoping/test/fixtures/tdz/function-call-recursive-reference/output.js

@@ -0,0 +1,12 @@
+var x = babelHelpers.temporalUndefined;
+
+function f(i) {
+  return () => {
+    babelHelpers.temporalRef(x, "x");
+    f(i - 1);
+  };
+}
+
+var g = f(1);
+x = void 0;
+g();

packages/babel-traverse/src/path/introspection.js

@@ -361,6 +361,12 @@ export function _guessExecutionStatusRelativeTo(
   return keyPosition.target > keyPosition.this ? "before" : "after";
 }
 
+// Used to avoid infinite recursion in cases like
+//   function f() { if (false) f(); }
+//   f();
+// It also works with indirect recursion.
+const executionOrderCheckedNodes = new WeakSet();
+
 export function _guessExecutionStatusRelativeToDifferentFunctions(
   target: NodePath,
 ): RelativeExecutionStatus {
@@ -392,8 +398,14 @@ export function _guessExecutionStatusRelativeToDifferentFunctions(
       return "unknown";
     }
 
+    // Prevent infinte loops in recursive functions
+    if (executionOrderCheckedNodes.has(path.node)) continue;
+    executionOrderCheckedNodes.add(path.node);
+
     const status = this._guessExecutionStatusRelativeTo(path);
 
+    executionOrderCheckedNodes.delete(path.node);
+
     if (allStatus && allStatus !== status) {
       return "unknown";
     } else {