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fix(eslint-plugin): [no-base-to-string] don't crash for recursive array or tuple types #10633

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Merged
merged 5 commits into from
Jan 20, 2025
Merged

fix(eslint-plugin): [no-base-to-string] don't crash for recursive array or tuple types #10633

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fbeb999
don't crash for recursive array or tuple types
ronami Jan 7, 2025
5b74c62
testing adjustments
ronami Jan 8, 2025
ea7e77c
change test
ronami Jan 8, 2025
24da033
change test
ronami Jan 8, 2025
75d2265
simplify passing of 'visited' for array-join
ronami Jan 19, 2025
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60 changes: 44 additions & 16 deletions packages/eslint-plugin/src/rules/no-base-to-string.ts
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ export default createRule<Options, MessageIds>({
}
const certainty = collectToStringCertainty(
type ?? services.getTypeAtLocation(node),
new Set(),
);
if (certainty === Usefulness.Always) {
return;
Expand All @@ -93,7 +94,7 @@ export default createRule<Options, MessageIds>({
node: TSESTree.Node,
type: ts.Type,
): void {
const certainty = collectJoinCertainty(type);
const certainty = collectJoinCertainty(type, new Set());

if (certainty === Usefulness.Always) {
return;
Expand Down Expand Up @@ -140,9 +141,14 @@ export default createRule<Options, MessageIds>({
return Usefulness.Never;
}

function collectTupleCertainty(type: ts.TypeReference): Usefulness {
function collectTupleCertainty(
type: ts.TypeReference,
visited: Set<ts.Type>,
): Usefulness {
const typeArgs = checker.getTypeArguments(type);
const certainties = typeArgs.map(t => collectToStringCertainty(t));
const certainties = typeArgs.map(t =>
collectToStringCertainty(t, visited),
);
if (certainties.some(certainty => certainty === Usefulness.Never)) {
return Usefulness.Never;
}
Expand All @@ -154,39 +160,57 @@ export default createRule<Options, MessageIds>({
return Usefulness.Always;
}

function collectArrayCertainty(type: ts.Type): Usefulness {
function collectArrayCertainty(
type: ts.Type,
visited: Set<ts.Type>,
): Usefulness {
const elemType = nullThrows(
type.getNumberIndexType(),
'array should have number index type',
);
return collectToStringCertainty(elemType);
return collectToStringCertainty(elemType, visited);
}

function collectJoinCertainty(type: ts.Type): Usefulness {
function collectJoinCertainty(
type: ts.Type,
visited: Set<ts.Type>,
): Usefulness {
if (tsutils.isUnionType(type)) {
return collectUnionTypeCertainty(type, collectJoinCertainty);
return collectUnionTypeCertainty(type, t =>
collectJoinCertainty(t, visited),
);
}

if (tsutils.isIntersectionType(type)) {
return collectIntersectionTypeCertainty(type, collectJoinCertainty);
return collectIntersectionTypeCertainty(type, t =>
collectJoinCertainty(t, visited),
);
}

if (checker.isTupleType(type)) {
return collectTupleCertainty(type);
return collectTupleCertainty(type, visited);
}

if (checker.isArrayType(type)) {
return collectArrayCertainty(type);
return collectArrayCertainty(type, visited);
}

return Usefulness.Always;
}

function collectToStringCertainty(type: ts.Type): Usefulness {
function collectToStringCertainty(
type: ts.Type,
visited: Set<ts.Type>,
): Usefulness {
if (visited.has(type)) {
// don't report if this is a self referencing array or tuple type
return Usefulness.Always;
}

if (tsutils.isTypeParameter(type)) {
const constraint = type.getConstraint();
if (constraint) {
return collectToStringCertainty(constraint);
return collectToStringCertainty(constraint, visited);
}
// unconstrained generic means `unknown`
return Usefulness.Always;
Expand All @@ -205,19 +229,23 @@ export default createRule<Options, MessageIds>({
}

if (type.isIntersection()) {
return collectIntersectionTypeCertainty(type, collectToStringCertainty);
return collectIntersectionTypeCertainty(type, t =>
collectToStringCertainty(t, visited),
);
}

if (type.isUnion()) {
return collectUnionTypeCertainty(type, collectToStringCertainty);
return collectUnionTypeCertainty(type, t =>
collectToStringCertainty(t, visited),
);
}

if (checker.isTupleType(type)) {
return collectTupleCertainty(type);
return collectTupleCertainty(type, new Set([...visited, type]));
}

if (checker.isArrayType(type)) {
return collectArrayCertainty(type);
return collectArrayCertainty(type, new Set([...visited, type]));
}

const toString =
Expand Down
94 changes: 94 additions & 0 deletions packages/eslint-plugin/tests/rules/no-base-to-string.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -483,6 +483,34 @@ function foo<T>(x: T) {
declare const u: unknown;
String(u);
`,
`
type Value = string | Value[];
declare const v: Value;

String(v);
`,
`
type Value = (string | Value)[];
declare const v: Value;

String(v);
`,
`
type Value = Value[];
declare const v: Value;

String(v);
Comment on lines +499 to +502
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@ronami ronami Jan 8, 2025 •
edited
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To my understanding, types like this are valid to stringify.

`,
`
type Value = [Value];
declare const v: Value;

String(v);
`,
`
declare const v: ('foo' | 'bar')[][];
String(v);
`,
],
invalid: [
{
Expand Down Expand Up @@ -1811,5 +1839,71 @@ foo.toString();
},
],
},
{
code: `
type Value = { foo: string } | Value[];
declare const v: Value;

String(v);
`,
errors: [
{
data: {
certainty: 'may',
name: 'v',
},
messageId: 'baseToString',
},
],
},
{
code: `
type Value = ({ foo: string } | Value)[];
declare const v: Value;

String(v);
`,
errors: [
{
data: {
certainty: 'may',
name: 'v',
},
messageId: 'baseToString',
},
],
},
{
code: `
type Value = [{ foo: string }, Value];
declare const v: Value;

String(v);
`,
errors: [
{
data: {
certainty: 'will',
name: 'v',
},
messageId: 'baseToString',
},
],
},
{
code: `
declare const v: { foo: string }[][];
v.join();
`,
errors: [
{
data: {
certainty: 'will',
name: 'v',
},
messageId: 'baseArrayJoin',
},
],
},
],
});
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