[compiler] Validate static components

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Pipeline.ts

@@ -102,6 +102,7 @@ import {optimizePropsMethodCalls} from '../Optimization/OptimizePropsMethodCalls
 import {transformFire} from '../Transform';
 import {validateNoImpureFunctionsInRender} from '../Validation/ValiateNoImpureFunctionsInRender';
 import {CompilerError} from '..';
+import {validateStaticComponents} from '../Validation/ValidateStaticComponents';
 
 export type CompilerPipelineValue =
   | {kind: 'ast'; name: string; value: CodegenFunction}
@@ -293,6 +294,10 @@ function runWithEnvironment(
   });
 
   if (env.isInferredMemoEnabled) {
+    if (env.config.validateStaticComponents) {
+      env.logErrors(validateStaticComponents(hir));
+    }
+
     /**
      * Only create reactive scopes (which directly map to generated memo blocks)
      * if inferred memoization is enabled. This makes all later passes which

compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts

@@ -330,6 +330,11 @@ const EnvironmentConfigSchema = z.object({
    */
   validateNoJSXInTryStatements: z.boolean().default(false),
 
+  /**
+   * Validates against dynamically creating components during render.
+   */
+  validateStaticComponents: z.boolean().default(false),
+
   /**
    * Validates that the dependencies of all effect hooks are memoized. This helps ensure
    * that Forget does not introduce infinite renders caused by a dependency changing,
@@ -932,6 +937,19 @@ export class Environment {
     return makeScopeId(this.#nextScope++);
   }
 
+  logErrors(errors: Result<void, CompilerError>): void {
+    if (errors.isOk() || this.logger == null) {
+      return;
+    }
+    for (const error of errors.unwrapErr().details) {
+      this.logger.logEvent(this.filename, {
+        kind: 'CompileError',
+        detail: error,
+        fnLoc: null,
+      });
+    }
+  }
+
   isContextIdentifier(node: t.Identifier): boolean {
     return this.#contextIdentifiers.has(node);
   }

compiler/packages/babel-plugin-react-compiler/src/Validation/ValidateStaticComponents.ts

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {CompilerError, ErrorSeverity} from '../CompilerError';
+import {HIRFunction, IdentifierId, SourceLocation} from '../HIR';
+import {Err, Ok, Result} from '../Utils/Result';
+
+/**
+ * Validates against components that are created dynamically and whose identity is not guaranteed
+ * to be stable (which would cause the component to reset on each re-render).
+ */
+export function validateStaticComponents(
+  fn: HIRFunction,
+): Result<void, CompilerError> {
+  const error = new CompilerError();
+  const knownDynamicComponents = new Map<IdentifierId, SourceLocation>();
+  for (const block of fn.body.blocks.values()) {
+    phis: for (const phi of block.phis) {
+      for (const operand of phi.operands.values()) {
+        const loc = knownDynamicComponents.get(operand.identifier.id);
+        if (loc != null) {
+          knownDynamicComponents.set(phi.place.identifier.id, loc);
+          continue phis;
+        }
+      }
+    }
+    for (const instr of block.instructions) {
+      const {lvalue, value} = instr;
+      switch (value.kind) {
+        case 'FunctionExpression':
+        case 'NewExpression':
+        case 'MethodCall':
+        case 'CallExpression': {
+          knownDynamicComponents.set(lvalue.identifier.id, value.loc);
+          break;
+        }
+        case 'LoadLocal': {
+          const loc = knownDynamicComponents.get(value.place.identifier.id);
+          if (loc != null) {
+            knownDynamicComponents.set(lvalue.identifier.id, loc);
+          }
+          break;
+        }
+        case 'StoreLocal': {
+          const loc = knownDynamicComponents.get(value.value.identifier.id);
+          if (loc != null) {
+            knownDynamicComponents.set(lvalue.identifier.id, loc);
+            knownDynamicComponents.set(value.lvalue.place.identifier.id, loc);
+          }
+          break;
+        }
+        case 'JsxExpression': {
+          if (value.tag.kind === 'Identifier') {
+            const location = knownDynamicComponents.get(
+              value.tag.identifier.id,
+            );
+            if (location != null) {
+              error.push({
+                reason: `Components created during render will reset their state each time they are created. Declare components outside of render. `,
+                severity: ErrorSeverity.InvalidReact,
+                loc: value.tag.loc,
+                description: null,
+                suggestions: null,
+              });
+              error.push({
+                reason: `The component may be created during render`,
+                severity: ErrorSeverity.InvalidReact,
+                loc: location,
+                description: null,
+                suggestions: null,
+              });
+            }
+          }
+        }
+      }
+    }
+  }
+  if (error.hasErrors()) {
+    return Err(error);
+  } else {
+    return Ok(undefined);
+  }
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-conditionally-assigned-dynamically-constructed-component-in-render.expect.md

@@ -0,0 +1,59 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  let Component;
+  if (props.cond) {
+    Component = createComponent();
+  } else {
+    Component = DefaultComponent;
+  }
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(3);
+  let Component;
+  if (props.cond) {
+    let t0;
+    if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+      t0 = createComponent();
+      $[0] = t0;
+    } else {
+      t0 = $[0];
+    }
+    Component = t0;
+  } else {
+    Component = DefaultComponent;
+  }
+  let t0;
+  if ($[1] !== Component) {
+    t0 = <Component />;
+    $[1] = Component;
+    $[2] = t0;
+  } else {
+    t0 = $[2];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":9,"column":10,"index":194},"end":{"line":9,"column":19,"index":203},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":5,"column":16,"index":116},"end":{"line":5,"column":33,"index":133},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":10,"column":1,"index":209},"filename":"invalid-conditionally-assigned-dynamically-constructed-component-in-render.ts"},"fnName":"Example","memoSlots":3,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-conditionally-assigned-dynamically-constructed-component-in-render.js

@@ -0,0 +1,10 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  let Component;
+  if (props.cond) {
+    Component = createComponent();
+  } else {
+    Component = DefaultComponent;
+  }
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-construct-component-in-render.expect.md

@@ -0,0 +1,41 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = createComponent();
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const Component = createComponent();
+    t0 = <Component />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":10,"index":112},"end":{"line":4,"column":19,"index":121},"filename":"invalid-dynamically-construct-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":20,"index":83},"end":{"line":3,"column":37,"index":100},"filename":"invalid-dynamically-construct-component-in-render.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":5,"column":1,"index":127},"filename":"invalid-dynamically-construct-component-in-render.ts"},"fnName":"Example","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-construct-component-in-render.js

@@ -0,0 +1,5 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = createComponent();
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-function.expect.md

@@ -0,0 +1,46 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  function Component() {
+    return <div />;
+  }
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    const Component = function Component() {
+      return <div />;
+    };
+
+    t0 = <Component />;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":6,"column":10,"index":122},"end":{"line":6,"column":19,"index":131},"filename":"invalid-dynamically-constructed-component-function.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":2,"index":65},"end":{"line":5,"column":3,"index":111},"filename":"invalid-dynamically-constructed-component-function.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":7,"column":1,"index":137},"filename":"invalid-dynamically-constructed-component-function.ts"},"fnName":"Example","memoSlots":1,"memoBlocks":1,"memoValues":1,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-function.js

@@ -0,0 +1,7 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  function Component() {
+    return <div />;
+  }
+  return <Component />;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-method-call.expect.md

@@ -0,0 +1,50 @@
+
+## Input
+
+```javascript
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = props.foo.bar();
+  return <Component />;
+}
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react/compiler-runtime"; // @logger @validateStaticComponents
+function Example(props) {
+  const $ = _c(4);
+  let t0;
+  if ($[0] !== props.foo) {
+    t0 = props.foo.bar();
+    $[0] = props.foo;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  const Component = t0;
+  let t1;
+  if ($[2] !== Component) {
+    t1 = <Component />;
+    $[2] = Component;
+    $[3] = t1;
+  } else {
+    t1 = $[3];
+  }
+  return t1;
+}
+
+```
+
+## Logs
+
+```
+{"kind":"CompileError","detail":{"options":{"reason":"Components created during render will reset their state each time they are created. Declare components outside of render. ","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":4,"column":10,"index":110},"end":{"line":4,"column":19,"index":119},"filename":"invalid-dynamically-constructed-component-method-call.ts"}}},"fnLoc":null}
+{"kind":"CompileError","detail":{"options":{"reason":"The component may be created during render","description":null,"severity":"InvalidReact","suggestions":null,"loc":{"start":{"line":3,"column":20,"index":83},"end":{"line":3,"column":35,"index":98},"filename":"invalid-dynamically-constructed-component-method-call.ts"}}},"fnLoc":null}
+{"kind":"CompileSuccess","fnLoc":{"start":{"line":2,"column":0,"index":37},"end":{"line":5,"column":1,"index":125},"filename":"invalid-dynamically-constructed-component-method-call.ts"},"fnName":"Example","memoSlots":4,"memoBlocks":2,"memoValues":2,"prunedMemoBlocks":0,"prunedMemoValues":0}
+```
+
+### Eval output
+(kind: exception) Fixture not implemented

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/static-components/invalid-dynamically-constructed-component-method-call.js

@@ -0,0 +1,5 @@
+// @logger @validateStaticComponents
+function Example(props) {
+  const Component = props.foo.bar();
+  return <Component />;
+}