fix(vercel#38743): config.runtime support template literal

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

@@ -11,6 +11,7 @@ import type {
   ObjectExpression,
   RegExpLiteral,
   StringLiteral,
+  TemplateLiteral,
   VariableDeclaration,
 } from '@swc/core'
 
@@ -124,6 +125,10 @@ function isRegExpLiteral(node: Node): node is RegExpLiteral {
   return node.type === 'RegExpLiteral'
 }
 
+function isTemplateLiteral(node: Node): node is TemplateLiteral {
+  return node.type === 'TemplateLiteral'
+}
+
 class UnsupportedValueError extends Error {}
 class NoSuchDeclarationError extends Error {}
 
@@ -191,6 +196,33 @@ function extractValue(node: Node): any {
     }
 
     return obj
+  } else if (isTemplateLiteral(node)) {
+    // e.g. `abc`
+    if (node.expressions.length !== 0) {
+      // TODO: should we add support for `${'e'}d${'g'}'e'`?
+      throw new UnsupportedValueError()
+    }
+
+    // When TemplateLiteral has 0 expressions, the length of quasis is always 1.
+    // Because when parsing TemplateLiteral, the parser yields the first quasi,
+    // then the first expression, then the next quasi, then the next expression, etc.,
+    // until the last quasi.
+    // Thus if there is no expression, the parser ends at the frst and also last quasis
+    const firstQuasis = node.quasis[0]
+
+    // A "cooked" interpretation where backslashes have special meaning, while a
+    // "raw" interpretation where backslashes do not have special meaning
+    // https://exploringjs.com/impatient-js/ch_template-literals.html#template-strings-cooked-vs-raw
+    const { cooked } = firstQuasis
+
+    // FIXME: The type definition of "cooked" and "raw" (from swc) are outdated.
+    // Both of them should be string | null | undefined, not StringLiteral.
+    // It is a temporary type guard to make TypeScript happy.
+    // https://github.com/swc-project/swc/issues/4501
+    if (cooked == null || typeof cooked === 'string') {
+      return cooked
+    }
+    return extractValue(cooked)
   } else {
     throw new UnsupportedValueError()
   }

test/e2e/switchable-runtime/index.test.ts

@@ -115,11 +115,15 @@ describe('Switchable runtime', () => {
         )
       })
 
-      it('should build /api/hello as an api route with edge runtime', async () => {
-        const response = await fetchViaHTTP(context.appPort, '/api/hello')
-        const text = await response.text()
+      it('should build /api/hello and /api/edge as an api route with edge runtime', async () => {
+        let response = await fetchViaHTTP(context.appPort, '/api/hello')
+        let text = await response.text()
         expect(text).toMatch(/Hello from .+\/api\/hello/)
 
+        response = await fetchViaHTTP(context.appPort, '/api/edge')
+        text = await response.text()
+        expect(text).toMatch(/Returned by Edge API Route .+\/api\/edge/)
+
         if (!(global as any).isNextDeploy) {
           const manifest = await readJson(
             join(context.appDir, '.next/server/middleware-manifest.json')
@@ -137,6 +141,17 @@ describe('Switchable runtime', () => {
                 regexp: '^/api/hello$',
                 wasm: [],
               },
+              '/api/edge': {
+                env: [],
+                files: [
+                  'server/edge-runtime-webpack.js',
+                  'server/pages/api/edge.js',
+                ],
+                name: 'pages/api/hello',
+                page: '/api/edge',
+                regexp: '^/api/edge$',
+                wasm: [],
+              },
             },
           })
         }
@@ -235,11 +250,15 @@ describe('Switchable runtime', () => {
         })
       })
 
-      it('should build /api/hello as an api route with edge runtime', async () => {
-        const response = await fetchViaHTTP(context.appPort, '/api/hello')
-        const text = await response.text()
+      it('should build /api/hello and /api/edge as an api route with edge runtime', async () => {
+        let response = await fetchViaHTTP(context.appPort, '/api/hello')
+        let text = await response.text()
         expect(text).toMatch(/Hello from .+\/api\/hello/)
 
+        response = await fetchViaHTTP(context.appPort, '/api/edge')
+        text = await response.text()
+        expect(text).toMatch(/Returned by Edge API Route .+\/api\/edge/)
+
         if (!(global as any).isNextDeploy) {
           const manifest = await readJson(
             join(context.appDir, '.next/server/middleware-manifest.json')
@@ -257,6 +276,17 @@ describe('Switchable runtime', () => {
                 regexp: '^/api/hello$',
                 wasm: [],
               },
+              '/api/edge': {
+                env: [],
+                files: [
+                  'server/edge-runtime-webpack.js',
+                  'server/pages/api/edge.js',
+                ],
+                name: 'pages/api/edge',
+                page: '/api/edge',
+                regexp: '^/api/edge$',
+                wasm: [],
+              },
             },
           })
         }

test/e2e/switchable-runtime/pages/api/edge.js

@@ -0,0 +1,7 @@
+export default (req) => {
+  return new Response(`Returned by Edge API Route ${req.url}`)
+}
+
+export const config = {
+  runtime: `experimental-edge`,
+}