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Breaking: check unnamed default export in func-names (fixes #12194) #12195

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merged 4 commits into from Feb 17, 2020
Merged

Breaking: check unnamed default export in func-names (fixes #12194) #12195

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18b29ac
Breaking: check unnamed default export in func-names (fixes #12194)
golopot Aug 31, 2019
036ce53
docs: add that default export functions are checked
golopot Feb 17, 2020
e03ba83
Revert "docs: add that default export functions are checked"
golopot Feb 17, 2020
2421ed9
docs: add a note that export default functions needs name
golopot Feb 17, 2020
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12 changes: 10 additions & 2 deletions docs/rules/func-names.md
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Expand Up @@ -16,8 +16,8 @@ This rule can enforce or disallow the use of named function expressions.

This rule has a string option:

* `"always"` (default) requires function expressions to have a name
* `"as-needed"` requires function expressions to have a name, if the name cannot be assigned automatically in an ES6 environment
* `"always"` (default) requires function expressions and default export functions to have a name
* `"as-needed"` requires function expressions and default export functions to have a name, if the name cannot be assigned automatically in an ES6 environment
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* `"never"` disallows named function expressions, except in recursive functions, where a name is needed

This rule has an object option:
Expand Down Expand Up @@ -45,6 +45,8 @@ const cat = {
(function() {
// ...
}())

export default function() {}
```

Examples of **correct** code for this rule with the default `"always"` option:
Expand All @@ -61,6 +63,8 @@ const cat = {
(function bar() {
// ...
}())

export default function foo() {}
```

### as-needed
Expand All @@ -77,6 +81,8 @@ Foo.prototype.bar = function() {};
(function() {
// ...
}())

export default function() {}
```

Examples of **correct** code for this rule with the `"as-needed"` option:
Expand All @@ -93,6 +99,8 @@ const cat = {
(function bar() {
// ...
}())

export default function foo() {}
```

### never
Expand Down
53 changes: 30 additions & 23 deletions lib/rules/func-names.js
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Expand Up @@ -119,7 +119,6 @@ module.exports = {
(parent.type === "VariableDeclarator" && parent.id.type === "Identifier" && parent.init === node) ||
(parent.type === "Property" && parent.value === node) ||
(parent.type === "AssignmentExpression" && parent.left.type === "Identifier" && parent.right === node) ||
(parent.type === "ExportDefaultDeclaration" && parent.declaration === node) ||
(parent.type === "AssignmentPattern" && parent.right === node);
}

Expand Down Expand Up @@ -151,33 +150,41 @@ module.exports = {
});
}

return {
"FunctionExpression:exit"(node) {
/**
* The listener for function nodes.
* @param {ASTNode} node function node
* @returns {void}
*/
function handleFunction(node) {

// Skip recursive functions.
const nameVar = context.getDeclaredVariables(node)[0];
// Skip recursive functions.
const nameVar = context.getDeclaredVariables(node)[0];

if (isFunctionName(nameVar) && nameVar.references.length > 0) {
return;
}
if (isFunctionName(nameVar) && nameVar.references.length > 0) {
return;
}

const hasName = Boolean(node.id && node.id.name);
const config = getConfigForNode(node);

if (config === "never") {
if (hasName) {
reportUnexpectedNamedFunction(node);
}
} else if (config === "as-needed") {
if (!hasName && !hasInferredName(node)) {
reportUnexpectedUnnamedFunction(node);
}
} else {
if (!hasName && !isObjectOrClassMethod(node)) {
reportUnexpectedUnnamedFunction(node);
}
const hasName = Boolean(node.id && node.id.name);
const config = getConfigForNode(node);

if (config === "never") {
if (hasName && node.type !== "FunctionDeclaration") {
reportUnexpectedNamedFunction(node);
}
} else if (config === "as-needed") {
if (!hasName && !hasInferredName(node)) {
reportUnexpectedUnnamedFunction(node);
}
} else {
if (!hasName && !isObjectOrClassMethod(node)) {
reportUnexpectedUnnamedFunction(node);
}
}
}

return {
"FunctionExpression:exit": handleFunction,
"ExportDefaultDeclaration > FunctionDeclaration": handleFunction
};
}
};
65 changes: 57 additions & 8 deletions tests/lib/rules/func-names.js
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Expand Up @@ -64,14 +64,6 @@ ruleTester.run("func-names", rule, {
code: "(foo = function(){});",
options: ["as-needed"]
},
{
code: "export default (function(){});",
options: ["as-needed"],
parserOptions: {
ecmaVersion: 6,
sourceType: "module"
}
},
{
code: "({foo = function(){}} = {});",
options: ["as-needed"],
Expand Down Expand Up @@ -127,6 +119,28 @@ ruleTester.run("func-names", rule, {
parserOptions: { ecmaVersion: 6 }
},

// export default
{
code: "export default function foo() {}",
options: ["always"],
parserOptions: { sourceType: "module", ecmaVersion: 6 }
},
{
code: "export default function foo() {}",
options: ["as-needed"],
parserOptions: { sourceType: "module", ecmaVersion: 6 }
},
{
code: "export default function foo() {}",
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How is this valid? The option is "never" but the function has a name.

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That would require more checks, foo is here a declaration and can be used from within the module. And even if that's not the case, I believe this would break some builds

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The reasoning is that, under option never, function f() is allowed, export function f() is allowed, so likewise export default function f() should be allowed.

I understand in some perspective this should be reported, so this case is controvesial. Not reporting in this case would make both sides happy.

options: ["never"],
parserOptions: { sourceType: "module", ecmaVersion: 6 }
},
{
code: "export default function() {}",
options: ["never"],
parserOptions: { sourceType: "module", ecmaVersion: 6 }
},

// generators
{
code: "var foo = bar(function *baz() {});",
Expand Down Expand Up @@ -415,6 +429,41 @@ ruleTester.run("func-names", rule, {
}]
},

// export default
{
code: "export default function() {}",
options: ["always"],
parserOptions: { sourceType: "module", ecmaVersion: 6 },
errors: [{
messageId: "unnamed",
type: "FunctionDeclaration",
column: 16,
endColumn: 24
}]
},
{
code: "export default function() {}",
options: ["as-needed"],
parserOptions: { sourceType: "module", ecmaVersion: 6 },
errors: [{
messageId: "unnamed",
type: "FunctionDeclaration",
column: 16,
endColumn: 24
}]
},
{
code: "export default (function(){});",
options: ["as-needed"],
parserOptions: { sourceType: "module", ecmaVersion: 6 },
errors: [{
messageId: "unnamed",
type: "FunctionExpression",
column: 17,
endColumn: 25
}]
},

// generators
{
code: "var foo = bar(function *() {});",
Expand Down