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refactor(linter): add fixer for typescript-eslint/no-non-null-asserted-optional-chain #9993

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graphite-app merged 1 commit into from
Mar 24, 2025
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refactor(linter): add fixer for typescript-eslint/no-non-null-asserted-optional-chain #9993

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24 changes: 18 additions & 6 deletions crates/oxc_language_server/src/linter/snapshots/fixtures_linter_issue_9958_issue.ts.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -15,14 +15,26 @@ tags: None

code: "typescript-eslint(no-non-null-asserted-optional-chain)"
code_description.href: "https://oxc.rs/docs/guide/usage/linter/rules/typescript_eslint/no-non-null-asserted-optional-chain"
message: "non-null assertions after an optional chain expression\nhelp: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion."
range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 18 } }
related_information[0].message: ""
message: "Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.\nhelp: Remove the non-null assertion."
range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 19 } }
related_information[0].message: "non-null assertion made after optional chain"
related_information[0].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
related_information[0].location.range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 18 } }
related_information[1].message: ""
related_information[0].location.range: Range { start: Position { line: 11, character: 21 }, end: Position { line: 11, character: 22 } }
related_information[1].message: "optional chain used"
related_information[1].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
related_information[1].location.range: Range { start: Position { line: 11, character: 21 }, end: Position { line: 11, character: 21 } }
related_information[1].location.range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 19 } }
severity: Some(Error)
source: Some("oxc")
tags: None


code: "None"
code_description.href: "None"
message: "non-null assertion made after optional chain"
range: Range { start: Position { line: 11, character: 21 }, end: Position { line: 11, character: 22 } }
related_information[0].message: "original diagnostic"
related_information[0].location.uri: "file://<variable>/fixtures/linter/issue_9958/issue.ts"
related_information[0].location.range: Range { start: Position { line: 11, character: 18 }, end: Position { line: 11, character: 19 } }
severity: Some(Hint)
source: Some("oxc")
tags: None
62 changes: 49 additions & 13 deletions crates/oxc_linter/src/rules/typescript/no_non_null_asserted_optional_chain.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,10 +12,14 @@ use crate::{
rule::Rule,
};

fn no_non_null_asserted_optional_chain_diagnostic(span: Span, span1: Span) -> OxcDiagnostic {
OxcDiagnostic::warn("non-null assertions after an optional chain expression")
.with_help("Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.")
.with_labels([span, span1])
fn no_non_null_asserted_optional_chain_diagnostic(
chain_span: Span,
assertion_span: Span,
) -> OxcDiagnostic {
OxcDiagnostic::warn("Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.")
.with_help("Remove the non-null assertion.")
.with_label(assertion_span.primary_label("non-null assertion made after optional chain"))
.and_label(chain_span.label("optional chain used"))
}

#[derive(Debug, Default, Clone)]
Expand All @@ -27,20 +31,35 @@ declare_oxc_lint!(
/// Disallow non-null assertions after an optional chain expression.
///
/// ### Why is this bad?
/// `?.` optional chain expressions provide undefined if an object is null or undefined.
/// Using a `!` non-null assertion to assert the result of an `?.` optional chain expression is non-nullable is likely wrong.
///
/// Most of the time, either the object was not nullable and did not need the `?.` for its property lookup, or the `!` is incorrect and introducing a type safety hole.
/// By design, optional chain expressions (`?.`) provide `undefined` as the expression's value, if the object being
/// accessed is `null` or `undefined`, instead of throwing an error. Using a non-null assertion (`!`) to assert the
/// result of an optional chain expression is contradictory and likely wrong, as it indicates the code is both expecting
/// the value to be potentially `null` or `undefined` and non-null at the same time.
///
/// In most cases, either:
/// 1. The object is not nullable and did not need the `?.` for its property lookup
/// 2. The non-null assertion is incorrect and introduces a type safety hole.
///
/// ### Examples
///
/// Examples of **incorrect** code for this rule:
///
/// ### Example
/// ```ts
/// foo?.bar!;
/// foo?.bar()!;
/// ```
///
/// Examples of **correct** code for this rule:
///
/// ```ts
/// foo?.bar;
/// foo.bar!;
/// ```
NoNonNullAssertedOptionalChain,
typescript,
correctness,
pending
fix
);

impl Rule for NoNonNullAssertedOptionalChain {
Expand Down Expand Up @@ -90,10 +109,14 @@ impl Rule for NoNonNullAssertedOptionalChain {
if let Some(chain_span) = chain_span {
let chain_span_end = chain_span.end;
let non_null_end = non_null_expr.span.end - 1;
ctx.diagnostic(no_non_null_asserted_optional_chain_diagnostic(
Span::new(chain_span_end, chain_span_end),
Span::new(non_null_end, non_null_end),
));
let diagnostic = no_non_null_asserted_optional_chain_diagnostic(
Span::sized(chain_span_end, 1),
Span::sized(non_null_end, 1),
);
// ctx.diagnostic(diagnostic);
ctx.diagnostic_with_fix(diagnostic, |fixer| {
fixer.delete_range(Span::sized(non_null_end, 1))
});
}
}

Expand Down Expand Up @@ -143,11 +166,24 @@ fn test() {
"(foo?.bar!)()",
];

let fix = vec![
("foo?.bar!", "foo?.bar"),
("foo?.['bar']!", "foo?.['bar']"),
("foo?.bar()!", "foo?.bar()"),
("(foo?.bar)!.baz", "(foo?.bar).baz"),
("(foo?.bar)!().baz", "(foo?.bar)().baz"),
("(foo?.bar)!", "(foo?.bar)"),
("(foo?.bar)!()", "(foo?.bar)()"),
("(foo?.bar!)", "(foo?.bar)"),
("(foo?.bar!)()", "(foo?.bar)()"),
];

Tester::new(
NoNonNullAssertedOptionalChain::NAME,
NoNonNullAssertedOptionalChain::PLUGIN,
pass,
fail,
)
.expect_fix(fix)
.test_and_snapshot();
}
100 changes: 60 additions & 40 deletions crates/oxc_linter/src/snapshots/typescript_no_non_null_asserted_optional_chain.snap
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@@ -1,72 +1,92 @@
---
source: crates/oxc_linter/src/tester.rs
---
⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:4]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:9]
1 │ foo?.bar!;
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:4]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:13]
1 │ foo?.['bar']!;
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:4]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:11]
1 │ foo?.bar()!;
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:8]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:12]
1 │ foo.bar?.()!;
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:11]
1 │ (foo?.bar)!.baz
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:11]
1 │ (foo?.bar)!().baz
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:11]
1 │ (foo?.bar)!
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:11]
1 │ (foo?.bar)!()
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:10]
1 │ (foo?.bar!)
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.

⚠ typescript-eslint(no-non-null-asserted-optional-chain): non-null assertions after an optional chain expression
╭─[no_non_null_asserted_optional_chain.tsx:1:5]
⚠ typescript-eslint(no-non-null-asserted-optional-chain): Optional chain expressions can return undefined by design: using a non-null assertion is unsafe and wrong.
╭─[no_non_null_asserted_optional_chain.tsx:1:10]
1 │ (foo?.bar!)()
· ▲ ▲
· ┬ ┬
· │ ╰── non-null assertion made after optional chain
· ╰── optional chain used
╰────
help: Optional chain expressions can return undefined by design - using a non-null assertion is unsafe and wrong. You should remove the non-null assertion.
help: Remove the non-null assertion.