ValidateNoCapitalizedCalls checks capitalized methods

compiler/packages/babel-plugin-react-forget/src/Validation/ValidateNoCapitalizedCalls.ts

@@ -27,6 +27,7 @@ export function validateNoCapitalizedCalls(fn: HIRFunction): void {
   };
 
   const capitalLoadGlobals = new Map<IdentifierId, string>();
+  const capitalizedProperties = new Map<IdentifierId, string>();
   for (const [, block] of fn.body.blocks) {
     for (const { lvalue, value } of block.instructions) {
       switch (value.kind) {
@@ -54,6 +55,27 @@ export function validateNoCapitalizedCalls(fn: HIRFunction): void {
               suggestions: null,
             });
           }
+          break;
+        }
+        case "PropertyLoad": {
+          // Start conservative and disallow all capitalized method calls
+          if (/^[A-Z]/.test(value.property)) {
+            capitalizedProperties.set(lvalue.identifier.id, value.property);
+          }
+          break;
+        }
+        case "MethodCall": {
+          const propertyIdentifier = value.property.identifier.id;
+          const propertyName = capitalizedProperties.get(propertyIdentifier);
+          if (propertyName != null) {
+            CompilerError.throwInvalidReact({
+              reason: `Capitalized method calls may be calling components that use hooks, which make them dangerous to memoize. Ensure there are no hook calls in the function and rename it to begin with a lowercase letter to fix this error`,
+              description: `${propertyName} may be a component.`,
+              loc: value.loc,
+              suggestions: null,
+            });
+          }
+          break;
         }
       }
     }

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.capitalized-method-call.expect.md

@@ -0,0 +1,27 @@
+
+## Input
+
+```javascript
+// @validateNoCapitalizedCalls
+function Component() {
+  const x = someGlobal.SomeFunc();
+
+  return x;
+}
+
+```
+
+
+## Error
+
+```
+  1 | // @validateNoCapitalizedCalls
+  2 | function Component() {
+> 3 |   const x = someGlobal.SomeFunc();
+    |             ^^^^^^^^^^^^^^^^^^^^^ InvalidReact: Capitalized method calls may be calling components that use hooks, which make them dangerous to memoize. Ensure there are no hook calls in the function and rename it to begin with a lowercase letter to fix this error. SomeFunc may be a component. (3:3)
+  4 |
+  5 |   return x;
+  6 | }
+```
+          
+      

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/error.capitalized-method-call.js

@@ -0,0 +1,6 @@
+// @validateNoCapitalizedCalls
+function Component() {
+  const x = someGlobal.SomeFunc();
+
+  return x;
+}