From 685c87c9463ac815e836979054bc4fd91bdcad20 Mon Sep 17 00:00:00 2001
From: Shu Ding <g@shud.in>
Date: Wed, 23 Nov 2022 19:27:06 +0100
Subject: [PATCH] Show error for invalid page props in the TS plugin (#43300)

For page entries, currently it's only allowed to have `params` and
`searchParams` in props:

<img width="677" alt="CleanShot 2022-11-23 at 16 18 57@2x"
src="https://user-images.githubusercontent.com/3676859/203583323-12c24900-8046-4b3b-ac95-b0ed1bee37e4.png">

In the future, this will cover more cases for layout entries too.

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ]
[e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

Co-authored-by: Jiachi Liu <inbox@huozhi.im>
---
 packages/next/server/next-typescript.ts | 49 ++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/packages/next/server/next-typescript.ts b/packages/next/server/next-typescript.ts
index db244af381de..9ff0c6612ac5 100644
--- a/packages/next/server/next-typescript.ts
+++ b/packages/next/server/next-typescript.ts
@@ -29,11 +29,14 @@ const DISALLOWED_SERVER_REACT_APIS: string[] = [
 
 const ALLOWED_EXPORTS = ['config', 'generateStaticParams']
 
+const ALLOWED_PAGE_PROPS = ['params', 'searchParams']
+
 const NEXT_TS_ERRORS = {
   INVALID_SERVER_API: 71001,
   INVALID_ENTRY_EXPORT: 71002,
   INVALID_OPTION_VALUE: 71003,
   MISPLACED_CLIENT_ENTRY: 71004,
+  INVALID_PAGE_PROP: 71005,
 }
 
 const API_DOCS: Record<
@@ -197,7 +200,13 @@ export function createTSPlugin(modules: {
     const isAppEntryFile = (filePath: string) => {
       return (
         filePath.startsWith(appDir) &&
-        /(page|layout)\.(mjs|js|jsx|ts|tsx)$/.test(path.basename(filePath))
+        /^(page|layout)\.(mjs|js|jsx|ts|tsx)$/.test(path.basename(filePath))
+      )
+    }
+    const isPageFile = (filePath: string) => {
+      return (
+        filePath.startsWith(appDir) &&
+        /^page\.(mjs|js|jsx|ts|tsx)$/.test(path.basename(filePath))
       )
     }
 
@@ -666,6 +675,44 @@ export function createTSPlugin(modules: {
                 }
               }
             }
+          } else if (ts.isFunctionDeclaration(node)) {
+            let hasExportKeyword = false
+            let hasDefaultKeyword = false
+
+            if (node.modifiers) {
+              for (const modifier of node.modifiers) {
+                if (modifier.kind === ts.SyntaxKind.ExportKeyword) {
+                  hasExportKeyword = true
+                } else if (modifier.kind === ts.SyntaxKind.DefaultKeyword) {
+                  hasDefaultKeyword = true
+                }
+              }
+            }
+
+            // `export default function`
+            if (hasExportKeyword && hasDefaultKeyword) {
+              if (isPageFile(fileName)) {
+                const props = node.parameters?.[0]?.name
+                // For page entries (page.js), it can only have `params` and `searchParams`
+                // as the prop names.
+                if (props && ts.isObjectBindingPattern(props)) {
+                  for (const prop of (props as ts.ObjectBindingPattern)
+                    .elements) {
+                    const propName = prop.name.getText()
+                    if (!ALLOWED_PAGE_PROPS.includes(propName)) {
+                      prior.push({
+                        file: source,
+                        category: ts.DiagnosticCategory.Error,
+                        code: NEXT_TS_ERRORS.INVALID_PAGE_PROP,
+                        messageText: `"${propName}" is not a valid page property.`,
+                        start: prop.getStart(),
+                        length: prop.getWidth(),
+                      })
+                    }
+                  }
+                }
+              }
+            }
           }
         })
       }