Fix fbt (again)

compiler/forget/src/ReactiveScopes/MemoizeFbtOperandsInSameScope.ts

@@ -65,20 +65,20 @@ class Transform extends ReactiveFunctionVisitor<void> {
       (value.kind === "CallExpression" &&
         this.fbtValues.has(value.callee.identifier.id))
     ) {
+      const fbtScope = lvalue.identifier.scope;
+      if (fbtScope === null) {
+        return;
+      }
+
       // if the JSX element's tag was `fbt`, mark all its operands
       // to ensure that they end up in the same scope as the jsx element
       // itself.
       for (const operand of eachReactiveValueOperand(value)) {
-        operand.identifier.scope = lvalue.identifier.scope;
-        operand.identifier.mutableRange.end =
-          lvalue.identifier.mutableRange.end;
+        operand.identifier.scope = fbtScope;
 
         // Expand the jsx element's range to account for its operands
-        lvalue.identifier.mutableRange.start = makeInstructionId(
-          Math.min(
-            lvalue.identifier.mutableRange.start,
-            operand.identifier.mutableRange.start
-          )
+        fbtScope.range.start = makeInstructionId(
+          Math.min(fbtScope.range.start, operand.identifier.mutableRange.start)
         );
       }
     }

compiler/forget/src/__tests__/fixtures/compiler/fbt-template-string-same-scope.expect.md

@@ -0,0 +1,61 @@
+
+## Input
+
+```javascript
+import fbt from "fbt";
+
+export function Component(props) {
+  let count = 0;
+  if (props.items) {
+    count = props.items.length;
+  }
+  return (
+    <View>
+      {fbt(
+        `for ${fbt.param("count", count)} experiences`,
+        `Label for the number of items`,
+        { project: "public" }
+      )}
+    </View>
+  );
+}
+
+```
+
+## Code
+
+```javascript
+import { unstable_useMemoCache as useMemoCache } from "react";
+import fbt from "fbt";
+
+export function Component(props) {
+  const $ = useMemoCache(4);
+  let count = 0;
+  if (props.items) {
+    count = props.items.length;
+  }
+  const c_0 = $[0] !== count;
+  let t0;
+  if (c_0) {
+    t0 = fbt._("for {count} experiences", [fbt._param("count", count)], {
+      hk: "nmYpm",
+    });
+    $[0] = count;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  const c_2 = $[2] !== t0;
+  let t1;
+  if (c_2) {
+    t1 = <View>{t0}</View>;
+    $[2] = t0;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  return t1;
+}
+
+```
+      

compiler/forget/src/__tests__/fixtures/compiler/fbt-template-string-same-scope.js

@@ -0,0 +1,17 @@
+import fbt from "fbt";
+
+export function Component(props) {
+  let count = 0;
+  if (props.items) {
+    count = props.items.length;
+  }
+  return (
+    <View>
+      {fbt(
+        `for ${fbt.param("count", count)} experiences`,
+        `Label for the number of items`,
+        { project: "public" }
+      )}
+    </View>
+  );
+}