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[ts-next-plugin] fix: warn only if no type for separate export #78629

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Merged
devjiwonchoi merged 3 commits into from
Apr 29, 2025
Merged

[ts-next-plugin] fix: warn only if no type for separate export #78629

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6e4fcd0
[ts-next-plugin] fix: warn only if no type for separate export
devjiwonchoi Apr 28, 2025
1b4201d
update if early return
devjiwonchoi Apr 28, 2025
dda3708
update readability
devjiwonchoi Apr 28, 2025
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122 changes: 60 additions & 62 deletions packages/next/src/server/typescript/rules/metadata.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -166,95 +166,93 @@ const metadata = {
continue
}
const exportName = e.name.getText()
if (exportName !== 'generateMetadata' && exportName !== 'metadata') {
if (exportName !== 'metadata' && exportName !== 'generateMetadata') {
continue
}

// Get the symbol and type for the export
const symbol = typeChecker.getSymbolAtLocation(e.name)
if (!symbol) continue
if (!symbol) {
continue
}

const originalSymbol = typeChecker.getAliasedSymbol(symbol)
const declarations = originalSymbol.getDeclarations()
if (!declarations) {
continue
}

const type = typeChecker.getTypeOfSymbolAtLocation(symbol, e.name)
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@devjiwonchoi devjiwonchoi Apr 28, 2025

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This is unnecessary as is providing typeof value.

if (!type) continue
const declaration = declarations[0]
if (hasType(declaration)) {
continue
}

if (exportName === 'generateMetadata') {
let isAsync = false

// For export declarations, we need to get the actual declaration through the type checker
const originalSymbol = typeChecker.getAliasedSymbol(symbol)
const declaration = originalSymbol?.declarations?.[0]
// async function() {}
if (ts.isFunctionDeclaration(declaration)) {
isAsync =
declaration.modifiers?.some(
(m) => m.kind === ts.SyntaxKind.AsyncKeyword
) ?? false
}

if (declaration) {
if (ts.isFunctionDeclaration(declaration)) {
// foo = async function() {}
// foo = async () => {}
if (
ts.isVariableDeclaration(declaration) &&
declaration.initializer
) {
const initializer = declaration.initializer
const isFunction =
ts.isArrowFunction(initializer) ||
ts.isFunctionExpression(initializer)

if (isFunction) {
isAsync =
declaration.modifiers?.some(
initializer.modifiers?.some(
(m) => m.kind === ts.SyntaxKind.AsyncKeyword
) ?? false
} else if (
ts.isVariableDeclaration(declaration) &&
declaration.initializer
) {
if (
ts.isArrowFunction(declaration.initializer) ||
ts.isFunctionExpression(declaration.initializer)
) {
isAsync =
declaration.initializer.modifiers?.some(
(m) => m.kind === ts.SyntaxKind.AsyncKeyword
) ?? false
}
}
}

if (
declaration &&
ts.isFunctionDeclaration(declaration) &&
!hasType(declaration)
) {
diagnostics.push({
file: source,
category: ts.DiagnosticCategory.Warning,
code: NEXT_TS_ERRORS.INVALID_METADATA_EXPORT,
messageText: `The "generateMetadata" export should have a return type of ${isAsync ? '"Promise<Metadata>"' : '"Metadata"'} from "next".`,
start: e.name.getStart(),
length: e.name.getWidth(),
})
}
diagnostics.push({
file: source,
category: ts.DiagnosticCategory.Warning,
code: NEXT_TS_ERRORS.INVALID_METADATA_EXPORT,
messageText: `The Next.js "generateMetadata" export should have a return type of ${isAsync ? '"Promise<Metadata>"' : '"Metadata"'} from "next".`,
start: e.name.getStart(),
length: e.name.getWidth(),
})
} else {
// must be 'metadata' at this point
const declaration = symbol.declarations?.[0]
if (
declaration &&
ts.isVariableDeclaration(declaration) &&
!hasType(declaration)
) {
diagnostics.push({
file: source,
category: ts.DiagnosticCategory.Warning,
code: NEXT_TS_ERRORS.INVALID_METADATA_EXPORT,
messageText: `The Next.js "metadata" export should be type of "Metadata" from "next".`,
start: e.name.getStart(),
length: e.name.getWidth(),
})
}
diagnostics.push({
file: source,
category: ts.DiagnosticCategory.Warning,
code: NEXT_TS_ERRORS.INVALID_METADATA_EXPORT,
messageText: `The Next.js "metadata" export should be type of "Metadata" from "next".`,
start: e.name.getStart(),
length: e.name.getWidth(),
})
}
}
}

return diagnostics
},
},
}

function hasType(
node:
| tsModule.FunctionDeclaration
| tsModule.VariableDeclaration
| tsModule.FunctionExpression
| tsModule.ArrowFunction
): boolean {
function hasType(node: tsModule.Declaration): boolean {
const ts = getTs()

if (
!ts.isVariableDeclaration(node) &&
!ts.isFunctionDeclaration(node) &&
!ts.isArrowFunction(node) &&
!ts.isFunctionExpression(node)
) {
return false
}

// For function declarations, expressions, and arrow functions, check if they have return type
if (
ts.isFunctionDeclaration(node) ||
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