[TheeCoderAhmed]

Fixes #1821

not: {} generates any. No value can satisfy that schema, so never describes it better. With the schema from the issue, a union that allows exactly one of two properties comes out with externalId?: any and internalId?: any, so TypeScript accepts objects that set both.

Changing that output can break existing code, so after review it's now behind a new option: emptyNotAsNever in generateApi, --empty-not-as-never on the CLI. It is off by default and generated output doesn't change unless you turn it on.

With it on, not: {} and not: true generate never. true is not in the issue, but it accepts every value just like {}. Any other not still generates any, including annotation-only schemas such as not: { description: "..." }. The changeset is now a minor bump.

What I ran, on Node 22:

• tests/spec/not-empty-schema has two tests. With the old parser, the option-on test fails at expect(content).toContain("externalId?: never;"). The default-off test passes with both.
• vitest run: 306 tests in 101 files pass, with no snapshot changes.
• biome check on the changed files reports one error, organizeImports at types/index.ts:1:1. This PR doesn't touch those lines.

What I did not run: bun run build, or Node 20, 24 and 25.

---

Summary by cubic

Fixes #1821 by adding an opt-in emptyNotAsNever option (--empty-not-as-never) that generates never instead of any for not: {} and not: true schemas, which accept every value and so can never be satisfied. Previously NotSchemaParser always returned any, letting TypeScript accept objects in the "exactly one of these properties" pattern that set both. The option is off by default, so existing generated output is unchanged unless it's enabled. Other not schemas still generate any because TypeScript cannot express them. Adds a changeset and a spec test.

^{Written for commit ca0f680. Summary will update on new commits.}

[changeset-bot]

🦋 Changeset detected

Latest commit: ca0f680

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
swagger-typescript-api	Minor

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[cubic-dev-ai]

1 issue found across 4 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/schema-parser/complex-schema-parsers/not.ts">

<violation number="1" location="src/schema-parser/complex-schema-parsers/not.ts:8">
P2: This exact-equality check misses annotation-only schemas such as `not: { description: "..." }`. Annotations impose no validation constraints, so their negation is also impossible, yet this returns `any` and allows invalid values; detect schemas with no validation keywords rather than only `{}`.</violation>
</file>

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[cubic-dev-ai]

P2: This exact-equality check misses annotation-only schemas such as not: { description: "..." }. Annotations impose no validation constraints, so their negation is also impossible, yet this returns any and allows invalid values; detect schemas with no validation keywords rather than only {}.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At src/schema-parser/complex-schema-parsers/not.ts, line 8:

<comment>This exact-equality check misses annotation-only schemas such as `not: { description: "..." }`. Annotations impose no validation constraints, so their negation is also impossible, yet this returns `any` and allows invalid values; detect schemas with no validation keywords rather than only `{}`.</comment>

<file context>
@@ -1,7 +1,14 @@
-    return this.config.Ts.Keyword.Any;
+    // `{}` and `true` accept every value, so negating them leaves no valid value.
+    const allowsNothing =
+      this.schema.not === true || isEqual(this.schema.not, {});
+
+    return allowsNothing
</file context>

[js2me]

Thank you!