feat(no-sync)!: move ts-declaration-location to peerDependencies

- Add `typescript` as an optional peer dependency for the `n/no-sync` rule, used on `lib/util/get-full-type-name.js`.
- Set `ts-declaration-location` as an optional peer dependency for the `n/no-sync` rule.
- Move `ts-declaration-location` to `devDependencies` for development and testing.
- Update the `n/no-sync` documentation to refer the updated peer dependency requirement.
- Update `n/no-sync` rule to conditionally require `ts-declaration-location` only when advanced ignores are used.
- Remove unused eslint-disable directive n/no-unpublished-require on `lib/util/get-full-type-name.js`, as `typescript` is now an optional peer dependency.

Author: risantos

docs/rules/no-sync.md

@@ -79,6 +79,13 @@ Examples of **correct** code for this rule with the `{ ignores: ['readFileSync']
 fs.readFileSync(somePath);
 ```
 
+> [!WARNING]
+> Advanced `ignores` options (object specifiers) require TypeScript and the [`ts-declaration-location`](https://www.npmjs.com/package/ts-declaration-location) package. This package is an **optional peer dependency** for the `n/no-sync` rule. If you want to use advanced TypeScript-based ignores, please install it in your project:
+>
+> ```sh
+> npm install --save-dev ts-declaration-location
+> ```
+
 ##### Advanced (TypeScript only)
 
 You can provide a list of specifiers to ignore. Specifiers are typed as follows:
@@ -102,6 +109,9 @@ type Specifier =
   }
 ```
 
+> [!NOTE]
+> To use advanced TypeScript-based ignores, you must have `ts-declaration-location` installed as a dependency in your project.
+
 ###### From a file
 
 Examples of **correct** code for this rule with the ignore file specifier:

lib/rules/no-sync.js

@@ -8,14 +8,6 @@ let typeMatchesSpecifier =
     /** @type {import('ts-declaration-location').default | undefined} */
     (undefined)
 
-try {
-    typeMatchesSpecifier =
-        /** @type {import('ts-declaration-location').default} */ (
-            /** @type {unknown} */ (require("ts-declaration-location"))
-        )
-
-    // eslint-disable-next-line no-empty -- Deliberately left empty.
-} catch {}
 const getTypeOfNode = require("../util/get-type-of-node")
 const getParserServices = require("../util/get-parser-services")
 const getFullTypeName = require("../util/get-full-type-name")
@@ -124,6 +116,27 @@ module.exports = {
         const selector = options.allowAtRootLevel
             ? selectors.map(selector => `:function ${selector}`)
             : selectors
+
+        const hasAdvancedIgnores = ignores.some(
+            ignore => typeof ignore !== "string"
+        )
+
+        // Only require `ts-declaration-location` if needed and not already required.
+        if (hasAdvancedIgnores) {
+            try {
+                typeMatchesSpecifier ||=
+                    /** @type {import('ts-declaration-location').default} */ (
+                        /** @type {unknown} */ (
+                        require("ts-declaration-location")
+                    )
+                )
+            } catch {
+                throw new Error(
+                    'ts-declaration-location not available. Rule "n/no-sync" is configured to use "ignores" option with a non-string value. This requires ts-declaration-location to be available.'
+                )
+            }
+        }
+
         return {
             /**
              * @param {import('estree').Identifier & {parent: import('estree').Node}} node
@@ -160,12 +173,6 @@ module.exports = {
                         )
                     }
 
-                    if (typeMatchesSpecifier === undefined) {
-                        throw new Error(
-                            'ts-declaration-location not available. Rule "n/no-sync" is configured to use "ignores" option with a non-string value. This requires ts-declaration-location to be available.'
-                        )
-                    }
-
                     type =
                         type === undefined
                             ? getTypeOfNode(node, parserServices)
@@ -177,7 +184,7 @@ module.exports = {
                             : fullName
 
                     if (
-                        typeMatchesSpecifier(
+                        typeMatchesSpecifier && typeMatchesSpecifier(
                             parserServices.program,
                             ignore,
                             type

lib/util/get-full-type-name.js

@@ -2,7 +2,6 @@
 
 const ts = (() => {
     try {
-        // eslint-disable-next-line n/no-unpublished-require
         return require("typescript")
     } catch {
         return null

package.json

@@ -14,7 +14,17 @@
         "types/index.d.ts"
     ],
     "peerDependencies": {
-        "eslint": ">=8.23.0"
+        "eslint": ">=8.23.0",
+        "ts-declaration-location": "^1.0.6",
+        "typescript": ">=4.8.4"
+    },
+    "peerDependenciesMeta": {
+        "ts-declaration-location": {
+            "optional": true
+        },
+        "typescript": {
+            "optional": true
+        }
     },
     "dependencies": {
         "@eslint-community/eslint-utils": "^4.5.0",
@@ -24,8 +34,7 @@
         "globals": "^15.11.0",
         "ignore": "^5.3.2",
         "minimatch": "^9.0.5",
-        "semver": "^7.6.3",
-        "ts-declaration-location": "^1.0.6"
+        "semver": "^7.6.3"
     },
     "devDependencies": {
         "@eslint/js": "^9.14.0",
@@ -51,6 +60,7 @@
         "punycode": "^2.3.1",
         "release-it": "^17.10.0",
         "rimraf": "^5.0.10",
+        "ts-declaration-location": "^1.0.6",
         "ts-ignore-import": "^4.0.1",
         "type-fest": "^4.26.1",
         "typescript": "~5.6"