Enable @typescript-eslint/no-use-before-define for functions

.eslintrc.json

@@ -68,7 +68,7 @@
         "@typescript-eslint/no-use-before-define": [
           "warn",
           {
-            "functions": false,
+            "functions": true,
             "classes": true,
             "variables": true,
             "enums": true,

packages/next/build/analysis/extract-const-value.ts

@@ -17,52 +17,6 @@ import type {
 
 export class NoSuchDeclarationError extends Error {}
 
-/**
- * Extracts the value of an exported const variable named `exportedName`
- * (e.g. "export const config = { runtime: 'experimental-edge' }") from swc's AST.
- * The value must be one of (or throws UnsupportedValueError):
- *   - string
- *   - boolean
- *   - number
- *   - null
- *   - undefined
- *   - array containing values listed in this list
- *   - object containing values listed in this list
- *
- * Throws NoSuchDeclarationError if the declaration is not found.
- */
-export function extractExportedConstValue(
-  module: Module,
-  exportedName: string
-): any {
-  for (const moduleItem of module.body) {
-    if (!isExportDeclaration(moduleItem)) {
-      continue
-    }
-
-    const declaration = moduleItem.declaration
-    if (!isVariableDeclaration(declaration)) {
-      continue
-    }
-
-    if (declaration.kind !== 'const') {
-      continue
-    }
-
-    for (const decl of declaration.declarations) {
-      if (
-        isIdentifier(decl.id) &&
-        decl.id.value === exportedName &&
-        decl.init
-      ) {
-        return extractValue(decl.init, [exportedName])
-      }
-    }
-  }
-
-  throw new NoSuchDeclarationError()
-}
-
 function isExportDeclaration(node: Node): node is ExportDeclaration {
   return node.type === 'ExportDeclaration'
 }
@@ -247,3 +201,49 @@ function extractValue(node: Node, path?: string[]): any {
     )
   }
 }
+
+/**
+ * Extracts the value of an exported const variable named `exportedName`
+ * (e.g. "export const config = { runtime: 'experimental-edge' }") from swc's AST.
+ * The value must be one of (or throws UnsupportedValueError):
+ *   - string
+ *   - boolean
+ *   - number
+ *   - null
+ *   - undefined
+ *   - array containing values listed in this list
+ *   - object containing values listed in this list
+ *
+ * Throws NoSuchDeclarationError if the declaration is not found.
+ */
+export function extractExportedConstValue(
+  module: Module,
+  exportedName: string
+): any {
+  for (const moduleItem of module.body) {
+    if (!isExportDeclaration(moduleItem)) {
+      continue
+    }
+
+    const declaration = moduleItem.declaration
+    if (!isVariableDeclaration(declaration)) {
+      continue
+    }
+
+    if (declaration.kind !== 'const') {
+      continue
+    }
+
+    for (const decl of declaration.declarations) {
+      if (
+        isIdentifier(decl.id) &&
+        decl.id.value === exportedName &&
+        decl.init
+      ) {
+        return extractValue(decl.init, [exportedName])
+      }
+    }
+  }
+
+  throw new NoSuchDeclarationError()
+}

packages/next/build/analysis/get-page-static-info.ts

@@ -22,79 +22,6 @@ export interface PageStaticInfo {
   middleware?: Partial<MiddlewareConfig>
 }
 
-/**
- * For a given pageFilePath and nextConfig, if the config supports it, this
- * function will read the file and return the runtime that should be used.
- * It will look into the file content only if the page *requires* a runtime
- * to be specified, that is, when gSSP or gSP is used.
- * Related discussion: https://github.com/vercel/next.js/discussions/34179
- */
-export async function getPageStaticInfo(params: {
-  nextConfig: Partial<NextConfig>
-  pageFilePath: string
-  isDev?: boolean
-  page?: string
-}): Promise<PageStaticInfo> {
-  const { isDev, pageFilePath, nextConfig, page } = params
-
-  const fileContent = (await tryToReadFile(pageFilePath, !isDev)) || ''
-  if (/runtime|getStaticProps|getServerSideProps|matcher/.test(fileContent)) {
-    const swcAST = await parseModule(pageFilePath, fileContent)
-    const { ssg, ssr } = checkExports(swcAST)
-
-    // default / failsafe value for config
-    let config: any = {}
-    try {
-      config = extractExportedConstValue(swcAST, 'config')
-    } catch (e) {
-      if (e instanceof UnsupportedValueError) {
-        warnAboutUnsupportedValue(pageFilePath, page, e)
-      }
-      // `export config` doesn't exist, or other unknown error throw by swc, silence them
-    }
-
-    if (
-      typeof config.runtime !== 'string' &&
-      typeof config.runtime !== 'undefined'
-    ) {
-      throw new Error(`Provided runtime `)
-    } else if (!isServerRuntime(config.runtime)) {
-      const options = Object.values(SERVER_RUNTIME).join(', ')
-      if (typeof config.runtime !== 'string') {
-        throw new Error(
-          `The \`runtime\` config must be a string. Please leave it empty or choose one of: ${options}`
-        )
-      } else {
-        throw new Error(
-          `Provided runtime "${config.runtime}" is not supported. Please leave it empty or choose one of: ${options}`
-        )
-      }
-    }
-
-    let runtime =
-      SERVER_RUNTIME.edge === config?.runtime
-        ? SERVER_RUNTIME.edge
-        : ssr || ssg
-        ? config?.runtime || nextConfig.experimental?.runtime
-        : undefined
-
-    if (runtime === SERVER_RUNTIME.edge) {
-      warnAboutExperimentalEdgeApiFunctions()
-    }
-
-    const middlewareConfig = getMiddlewareConfig(config, nextConfig)
-
-    return {
-      ssr,
-      ssg,
-      ...(middlewareConfig && { middleware: middlewareConfig }),
-      ...(runtime && { runtime }),
-    }
-  }
-
-  return { ssr: false, ssg: false }
-}
-
 /**
  * Receives a parsed AST from SWC and checks if it belongs to a module that
  * requires a runtime to be specified. Those are:
@@ -154,27 +81,6 @@ async function tryToReadFile(filePath: string, shouldThrow: boolean) {
   }
 }
 
-function getMiddlewareConfig(
-  config: any,
-  nextConfig: NextConfig
-): Partial<MiddlewareConfig> {
-  const result: Partial<MiddlewareConfig> = {}
-
-  if (config.matcher) {
-    result.pathMatcher = new RegExp(
-      getMiddlewareRegExpStrings(config.matcher, nextConfig).join('|')
-    )
-
-    if (result.pathMatcher.source.length > 4096) {
-      throw new Error(
-        `generated matcher config must be less than 4096 characters.`
-      )
-    }
-  }
-
-  return result
-}
-
 function getMiddlewareRegExpStrings(
   matcherOrMatchers: unknown,
   nextConfig: NextConfig
@@ -226,6 +132,27 @@ function getMiddlewareRegExpStrings(
   }
 }
 
+function getMiddlewareConfig(
+  config: any,
+  nextConfig: NextConfig
+): Partial<MiddlewareConfig> {
+  const result: Partial<MiddlewareConfig> = {}
+
+  if (config.matcher) {
+    result.pathMatcher = new RegExp(
+      getMiddlewareRegExpStrings(config.matcher, nextConfig).join('|')
+    )
+
+    if (result.pathMatcher.source.length > 4096) {
+      throw new Error(
+        `generated matcher config must be less than 4096 characters.`
+      )
+    }
+  }
+
+  return result
+}
+
 let warnedAboutExperimentalEdgeApiFunctions = false
 function warnAboutExperimentalEdgeApiFunctions() {
   if (warnedAboutExperimentalEdgeApiFunctions) {
@@ -258,3 +185,76 @@ function warnAboutUnsupportedValue(
 
   warnedUnsupportedValueMap.set(pageFilePath, true)
 }
+
+/**
+ * For a given pageFilePath and nextConfig, if the config supports it, this
+ * function will read the file and return the runtime that should be used.
+ * It will look into the file content only if the page *requires* a runtime
+ * to be specified, that is, when gSSP or gSP is used.
+ * Related discussion: https://github.com/vercel/next.js/discussions/34179
+ */
+export async function getPageStaticInfo(params: {
+  nextConfig: Partial<NextConfig>
+  pageFilePath: string
+  isDev?: boolean
+  page?: string
+}): Promise<PageStaticInfo> {
+  const { isDev, pageFilePath, nextConfig, page } = params
+
+  const fileContent = (await tryToReadFile(pageFilePath, !isDev)) || ''
+  if (/runtime|getStaticProps|getServerSideProps|matcher/.test(fileContent)) {
+    const swcAST = await parseModule(pageFilePath, fileContent)
+    const { ssg, ssr } = checkExports(swcAST)
+
+    // default / failsafe value for config
+    let config: any = {}
+    try {
+      config = extractExportedConstValue(swcAST, 'config')
+    } catch (e) {
+      if (e instanceof UnsupportedValueError) {
+        warnAboutUnsupportedValue(pageFilePath, page, e)
+      }
+      // `export config` doesn't exist, or other unknown error throw by swc, silence them
+    }
+
+    if (
+      typeof config.runtime !== 'string' &&
+      typeof config.runtime !== 'undefined'
+    ) {
+      throw new Error(`Provided runtime `)
+    } else if (!isServerRuntime(config.runtime)) {
+      const options = Object.values(SERVER_RUNTIME).join(', ')
+      if (typeof config.runtime !== 'string') {
+        throw new Error(
+          `The \`runtime\` config must be a string. Please leave it empty or choose one of: ${options}`
+        )
+      } else {
+        throw new Error(
+          `Provided runtime "${config.runtime}" is not supported. Please leave it empty or choose one of: ${options}`
+        )
+      }
+    }
+
+    let runtime =
+      SERVER_RUNTIME.edge === config?.runtime
+        ? SERVER_RUNTIME.edge
+        : ssr || ssg
+        ? config?.runtime || nextConfig.experimental?.runtime
+        : undefined
+
+    if (runtime === SERVER_RUNTIME.edge) {
+      warnAboutExperimentalEdgeApiFunctions()
+    }
+
+    const middlewareConfig = getMiddlewareConfig(config, nextConfig)
+
+    return {
+      ssr,
+      ssg,
+      ...(middlewareConfig && { middleware: middlewareConfig }),
+      ...(runtime && { runtime }),
+    }
+  }
+
+  return { ssr: false, ssg: false }
+}