From cb1fef44f056461c08a4b5db4efafde99da096cc Mon Sep 17 00:00:00 2001
From: Eli White <github@eli-white.com>
Date: Wed, 5 Feb 2025 18:08:14 -0800
Subject: [PATCH] Adding a test for nested ternaries

---
 .../src/Optimization/ConstantPropagation.ts   | 11 ++-
 ...propagation-ternary-nested-unary.expect.md | 83 +++++++++++++++++++
 ...nstant-propagation-ternary-nested-unary.js | 32 +++++++
 3 files changed, 120 insertions(+), 6 deletions(-)
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.expect.md
 create mode 100644 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.js

diff --git a/compiler/packages/babel-plugin-react-compiler/src/Optimization/ConstantPropagation.ts b/compiler/packages/babel-plugin-react-compiler/src/Optimization/ConstantPropagation.ts
index a447b0f71f..82e23e57e8 100644
--- a/compiler/packages/babel-plugin-react-compiler/src/Optimization/ConstantPropagation.ts
+++ b/compiler/packages/babel-plugin-react-compiler/src/Optimization/ConstantPropagation.ts
@@ -175,14 +175,13 @@ function applyConstantPropagation(
         if (testValue !== null && testValue.kind === 'Primitive') {
           hasChanges = true;
           const targetBlockId = testValue.value
-            ? /*
-               * Do I need to change these from being value blocks?
-               * Currently getting
-               * Invariant: Expected a fallthrough for value block (6:6)
-               */
-              branchBlock.terminal.consequent
+            ? branchBlock.terminal.consequent
             : branchBlock.terminal.alternate;
+
+          // I think I can only set this if the block isn't
+          // used in a value position by its predecessor
           block.kind = 'block';
+
           block.terminal = {
             kind: 'goto',
             variant: GotoVariant.Break,
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.expect.md b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.expect.md
new file mode 100644
index 0000000000..15e91fb923
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.expect.md
@@ -0,0 +1,83 @@
+
+## Input
+
+```javascript
+// @enableTernaryConstantPropagation
+import {Stringify} from 'shared-runtime';
+
+function foo() {
+  let _b;
+  const b = true;
+  _b = !b ? 'bar' : b ? 'foo' : 'baz';
+
+  return (
+    <Stringify
+      value={{
+        _b,
+        b0: !true,
+        n0: !0,
+        n1: !1,
+        n2: !2,
+        n3: !-1,
+        s0: !'',
+        s1: !'a',
+        s2: !'ab',
+        u: !undefined,
+        n: !null,
+      }}
+    />
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: foo,
+  params: [],
+  isComponent: false,
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @enableTernaryConstantPropagation
+import { Stringify } from "shared-runtime";
+
+function foo() {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = (
+      <Stringify
+        value={{
+          _b: "foo",
+          b0: false,
+          n0: true,
+          n1: false,
+          n2: false,
+          n3: !-1,
+          s0: true,
+          s1: false,
+          s2: false,
+          u: !undefined,
+          n: true,
+        }}
+      />
+    );
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: foo,
+  params: [],
+  isComponent: false,
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>{"value":{"_b":"foo","b0":false,"n0":true,"n1":false,"n2":false,"n3":false,"s0":true,"s1":false,"s2":false,"u":true,"n":true}}</div>
\ No newline at end of file
diff --git a/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.js b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.js
new file mode 100644
index 0000000000..3ef5c72b5d
--- /dev/null
+++ b/compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/constant-propagation-ternary-nested-unary.js
@@ -0,0 +1,32 @@
+// @enableTernaryConstantPropagation
+import {Stringify} from 'shared-runtime';
+
+function foo() {
+  let _b;
+  const b = true;
+  _b = !b ? 'bar' : b ? 'foo' : 'baz';
+
+  return (
+    <Stringify
+      value={{
+        _b,
+        b0: !true,
+        n0: !0,
+        n1: !1,
+        n2: !2,
+        n3: !-1,
+        s0: !'',
+        s1: !'a',
+        s2: !'ab',
+        u: !undefined,
+        n: !null,
+      }}
+    />
+  );
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: foo,
+  params: [],
+  isComponent: false,
+};