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refactor(compiler-cli): relax nullish coalescing non nullable diagnostics on indexed access #70656

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Merged
atscott merged 1 commit into from
Sep 10, 2026
Merged

refactor(compiler-cli): relax nullish coalescing non nullable diagnostics on indexed access #70656

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26 changes: 26 additions & 0 deletions packages/compiler-cli/src/ngtsc/typecheck/extended/api/api.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,12 @@ import {
ParseSourceSpan,
TmplAstNode,
TmplAstTemplate,
KeyedRead,
SafePropertyRead,
SafeKeyedRead,
SafeCall,
ParenthesizedExpression,
NonNullAssert,
} from '@angular/compiler';
import ts from 'typescript';

Expand Down Expand Up @@ -161,3 +167,23 @@ class TemplateVisitor<Code extends ErrorCode> extends CombinedRecursiveAstVisito
return this.diagnostics;
}
}

/**
* Checks if the given AST node originates from a KeyedRead (indexed access)
* by unwrapping parentheses, non-null assertions, and traversing the receivers
* of safe navigation operations (?. property access, ?.[] keyed access, ?.() calls).
*/
export function isAccessFromUncheckedIndex(node: AST): boolean {
if (node instanceof KeyedRead) {
return true;
} else if (
node instanceof SafePropertyRead ||
node instanceof SafeKeyedRead ||
node instanceof SafeCall
) {
return isAccessFromUncheckedIndex(node.receiver);
} else if (node instanceof ParenthesizedExpression || node instanceof NonNullAssert) {
return isAccessFromUncheckedIndex(node.expression);
}
return false;
}
17 changes: 15 additions & 2 deletions ...compiler-cli/src/ngtsc/typecheck/extended/checks/nullish_coalescing_not_nullable/index.ts
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Expand Up @@ -6,7 +6,7 @@
* found in the LICENSE file at https://angular.dev/license
*/

import {AST, Binary, TmplAstNode} from '@angular/compiler';
import {AST, Binary, KeyedRead, TmplAstNode} from '@angular/compiler';
import ts from 'typescript';

import {NgCompilerOptions} from '../../../../core/api';
Expand All @@ -17,6 +17,7 @@ import {
TemplateCheckWithVisitor,
TemplateContext,
formatExtendedError,
isAccessFromUncheckedIndex,
} from '../../api';

/**
Expand All @@ -28,13 +29,23 @@ import {
class NullishCoalescingNotNullableCheck extends TemplateCheckWithVisitor<ErrorCode.NULLISH_COALESCING_NOT_NULLABLE> {
override code = ErrorCode.NULLISH_COALESCING_NOT_NULLABLE as const;

constructor(private readonly noUncheckedIndexedAccess: boolean) {
super();
}

override visitNode(
ctx: TemplateContext<ErrorCode.NULLISH_COALESCING_NOT_NULLABLE>,
component: ts.ClassDeclaration,
node: TmplAstNode | AST,
): NgTemplateDiagnostic<ErrorCode.NULLISH_COALESCING_NOT_NULLABLE>[] {
if (!(node instanceof Binary) || node.operation !== '??') return [];

// When `noUncheckedIndexedAccess` is disabled, an indexed access is not checked
Comment thread
JeanMeche marked this conversation as resolved.
// and may result in `undefined`.
if (!this.noUncheckedIndexedAccess && isAccessFromUncheckedIndex(node.left)) {
return [];
}

const symbolLeft = ctx.templateTypeChecker.getSymbolOfNode(node.left, component);
if (symbolLeft === null || symbolLeft.kind !== SymbolKind.Expression) {
return [];
Expand Down Expand Up @@ -86,6 +97,8 @@ export const factory: TemplateCheckFactory<
return null;
}

return new NullishCoalescingNotNullableCheck();
const noUncheckedIndexedAccess = !!options.noUncheckedIndexedAccess;

return new NullishCoalescingNotNullableCheck(noUncheckedIndexedAccess);
},
};
3 changes: 2 additions & 1 deletion ...ges/compiler-cli/src/ngtsc/typecheck/extended/checks/optional_chain_not_nullable/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ import {
TemplateCheckWithVisitor,
TemplateContext,
formatExtendedError,
isAccessFromUncheckedIndex,
} from '../../api';

/**
Expand Down Expand Up @@ -54,7 +55,7 @@ class OptionalChainNotNullableCheck extends TemplateCheckWithVisitor<ErrorCode.O

// When `noUncheckedIndexedAccess` is disabled, an indexed access is not checked
// and may result in `undefined`.
if (node.receiver instanceof KeyedRead && !this.noUncheckedIndexedAccess) {
if (!this.noUncheckedIndexedAccess && isAccessFromUncheckedIndex(node.receiver)) {
return [];
}

Expand Down
156 changes: 151 additions & 5 deletions ...ended/test/checks/nullish_coalescing_not_nullable/nullish_coalescing_not_nullable_spec.ts
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Expand Up @@ -217,6 +217,155 @@ runInEachFileSystem(() => {
expect(diags.length).toBe(0);
});

it('should not produce nullish coalescing warning for an indexed access if noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ arr[0] ?? 'foo' }}`,
},
source: `
export class TestCmp {
arr: Array<string> = [];
}
`,
},
],
{options: {noUncheckedIndexedAccess: false}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[nullishCoalescingNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});

it('should not produce nullish coalescing warning for an indexed access if noUncheckedIndexedAccess is true', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ arr[0] ?? 'foo' }}`,
},
source: `
export class TestCmp {
arr: Array<string> = [];
}
`,
},
],
{options: {noUncheckedIndexedAccess: true}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[nullishCoalescingNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});

it('should not produce nullish coalescing warning for a SafePropertyRead off an indexed access if noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ foos[0]?.name ?? 'foo' }}`,
},
source: `
export class TestCmp {
foos: Array<{name: string}> = [];
}
`,
},
],
{options: {noUncheckedIndexedAccess: false}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[nullishCoalescingNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});

it('should not produce nullish coalescing warning for a SafeKeyedRead if noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ foos?.[0] ?? 'foo' }}`,
},
source: `
export class TestCmp {
foos: Array<string> | null = null;
}
`,
},
],
{options: {noUncheckedIndexedAccess: false}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[nullishCoalescingNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});

it('should not produce nullish coalescing warning for a parenthesized indexed access if noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ (foos[0]) ?? 'foo' }}`,
},
source: `
export class TestCmp {
foos: Array<string> = [];
}
`,
},
],
{options: {noUncheckedIndexedAccess: false}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[nullishCoalescingNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});
it('warns for pipe arguments which are likely configured incorrectly (?? operates on "format" here)', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup([
Expand Down Expand Up @@ -341,7 +490,7 @@ runInEachFileSystem(() => {
expect(diags.length).toBe(0);
});

it('should produce nullish coalescing warning for a non-nullable ElementAccessExpression', () => {
it('should not produce nullish coalescing warning for a non-nullable ElementAccessExpression when noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup([
{
Expand All @@ -362,10 +511,7 @@ runInEachFileSystem(() => {
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(1);
expect(diags[0].category).toBe(ts.DiagnosticCategory.Warning);
expect(diags[0].code).toBe(ngErrorCode(ErrorCode.NULLISH_COALESCING_NOT_NULLABLE));
expect(getSourceCodeForDiagnostic(diags[0])).toBe(`myDict[key] ?? 'foo'`);
expect(diags.length).toBe(0);
});

it('should respect configured diagnostic category', () => {
Expand Down
30 changes: 30 additions & 0 deletions ...heck/extended/test/checks/optional_chain_not_nullable/optional_chain_not_nullable_spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,36 @@ runInEachFileSystem(() => {
expect(diags.length).toBe(0);
});

it('should not produce optional chain warning for a chained safe property read off an indexed access if noUncheckedIndexedAccess is false', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
[
{
fileName,
templates: {
'TestCmp': `{{ arr[0]?.bar?.length }}`,
},
source: `
export class TestCmp {
arr: Array<{ bar: string }> = [];
}
`,
},
],
{options: {noUncheckedIndexedAccess: false}},
);
const sf = getSourceFileOrError(program, fileName);
const component = getClass(sf, 'TestCmp');
const extendedTemplateChecker = new ExtendedTemplateCheckerImpl(
templateTypeChecker,
program.getTypeChecker(),
[optionalChainNotNullableFactory],
{strictNullChecks: true} /* options */,
);
const diags = extendedTemplateChecker.getDiagnosticsForComponent(component);
expect(diags.length).toBe(0);
});

it('should produce optional chain warning for an indexed access if noUncheckedIndexedAccess is true', () => {
const fileName = absoluteFrom('/main.ts');
const {program, templateTypeChecker} = setup(
Expand Down