strict return types

.eslintrc.json

@@ -37,7 +37,8 @@
 			"rules": {
 				"no-shadow": "off",
 				"@typescript-eslint/no-shadow": "error",
-				"@typescript-eslint/array-type": ["error", { "default": "generic" }]
+				"@typescript-eslint/array-type": ["error", { "default": "generic" }],
+				"@typescript-eslint/explicit-function-return-type": "error"
 			}
 		}
 	]

cli/csstools-cli/src/cli.ts

@@ -48,7 +48,7 @@ import postcssTrigonometricFunctions from './plugins/postcss-trigonometric-funct
 import postcssUnsetValue from './plugins/postcss-unset-value';
 
 main();
-function main() {
+function main(): void {
 	switch (process.argv[2] ?? false) {
 		case 'css-blank-pseudo':
 			cssBlankPseudo();

cli/csstools-cli/src/plugins/css-blank-pseudo.ts

@@ -1,7 +1,7 @@
 import plugin from 'css-blank-pseudo';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function cssBlankPseudo() {
+export default function cssBlankPseudo(): void {
 	cli(
 		plugin,
 		['preserve', 'replaceWith'],

cli/csstools-cli/src/plugins/css-has-pseudo.ts

@@ -1,7 +1,7 @@
 import plugin from 'css-has-pseudo';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function cssHasPseudo() {
+export default function cssHasPseudo(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/css-prefers-color-scheme.ts

@@ -1,7 +1,7 @@
 import plugin from 'css-prefers-color-scheme';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function cssPrefersColorScheme() {
+export default function cssPrefersColorScheme(): void {
 	cli(
 		plugin,
 		['preserve', 'mediaQuery'],

cli/csstools-cli/src/plugins/postcss-attribute-case-insensitive.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-attribute-case-insensitive';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssAttributeCaseInsensitive() {
+export default function postcssAttributeCaseInsensitive(): void {
 	cli(
 		plugin,
 		[],

cli/csstools-cli/src/plugins/postcss-cascade-layers.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-cascade-layers';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssCascadeLayers() {
+export default function postcssCascadeLayers(): void {
 	cli(
 		plugin,
 		[],

cli/csstools-cli/src/plugins/postcss-color-function.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-color-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssColorFunction() {
+export default function postcssColorFunction(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties'],

cli/csstools-cli/src/plugins/postcss-color-functional-notation.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-color-functional-notation';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssColorFunctionalNotation() {
+export default function postcssColorFunctionalNotation(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-color-hex-alpha.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-color-hex-alpha';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssColorHexAlpha() {
+export default function postcssColorHexAlpha(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-color-mix-function.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-color-mix-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssColorMixFunction() {
+export default function postcssColorMixFunction(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties'],

cli/csstools-cli/src/plugins/postcss-color-rebeccapurple.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-color-rebeccapurple';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssColorRebeccaPurple() {
+export default function postcssColorRebeccaPurple(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-custom-media.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-custom-media';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssCustomMedia() {
+export default function postcssCustomMedia(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-custom-properties.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-custom-properties';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssCustomProperties() {
+export default function postcssCustomProperties(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-custom-selectors.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-custom-selectors';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssCustomSelectors() {
+export default function postcssCustomSelectors(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-dir-pseudo-class.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-dir-pseudo-class';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssDirPseudoClass() {
+export default function postcssDirPseudoClass(): void {
 	cli(
 		plugin,
 		['dir', 'preserve', 'shadow'],

cli/csstools-cli/src/plugins/postcss-double-position-gradients.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-double-position-gradients';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssDoublePositionGradients() {
+export default function postcssDoublePositionGradients(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties'],

cli/csstools-cli/src/plugins/postcss-exponential-functions.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-exponential-functions';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssExponentialFunctions() {
+export default function postcssExponentialFunctions(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-focus-visible.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-focus-visible';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssFocusVisible() {
+export default function postcssFocusVisible(): void {
 	cli(
 		plugin,
 		['preserve', 'replaceWith'],

cli/csstools-cli/src/plugins/postcss-focus-within.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-focus-within';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssFocusWithin() {
+export default function postcssFocusWithin(): void {
 	cli(
 		plugin,
 		['preserve', 'replaceWith'],

cli/csstools-cli/src/plugins/postcss-font-format-keywords.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-font-format-keywords';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssFontFormatKeywords() {
+export default function postcssFontFormatKeywords(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-gap-properties.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-gap-properties';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssGapProperties() {
+export default function postcssGapProperties(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-gradients-interpolation-method.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-gradients-interpolation-method';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssGradientsInterpolationMethod() {
+export default function postcssGradientsInterpolationMethod(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties'],

cli/csstools-cli/src/plugins/postcss-hwb-function.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-hwb-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssHWBFunction() {
+export default function postcssHWBFunction(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-ic-unit.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-ic-unit';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssICUnit() {
+export default function postcssICUnit(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties'],

cli/csstools-cli/src/plugins/postcss-image-set-function.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-image-set-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssImageSetFunction() {
+export default function postcssImageSetFunction(): void {
 	cli(
 		plugin,
 		['oninvalid', 'preserve'],

cli/csstools-cli/src/plugins/postcss-is-pseudo-class.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-is-pseudo-class';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssIsPseudoClass() {
+export default function postcssIsPseudoClass(): void {
 	cli(
 		plugin,
 		['onComplexSelector', 'preserve', 'specificityMatchingName'],

cli/csstools-cli/src/plugins/postcss-lab-function.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-lab-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLabFunction() {
+export default function postcssLabFunction(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties', 'subFeatures'],

cli/csstools-cli/src/plugins/postcss-light-dark-function.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-light-dark-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLightDarkFunction() {
+export default function postcssLightDarkFunction(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-logical-float-and-clear.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-logical-float-and-clear';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLogical() {
+export default function postcssLogical(): void {
 	cli(
 		plugin,
 		['inlineDirection', 'blockDirection'],

cli/csstools-cli/src/plugins/postcss-logical-resize.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-logical-resize';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLogicalResize() {
+export default function postcssLogicalResize(): void {
 	cli(
 		plugin,
 		['inlineDirection'],

cli/csstools-cli/src/plugins/postcss-logical-viewport-units.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-logical-viewport-units';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLogicalViewportUnits() {
+export default function postcssLogicalViewportUnits(): void {
 	cli(
 		plugin,
 		['inlineDirection', 'preserve'],

cli/csstools-cli/src/plugins/postcss-logical.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-logical';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssLogical() {
+export default function postcssLogical(): void {
 	cli(
 		plugin,
 		['inlineDirection', 'blockDirection'],

cli/csstools-cli/src/plugins/postcss-media-minmax.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-media-minmax';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssMediaMinMax() {
+export default function postcssMediaMinMax(): void {
 	cli(
 		plugin,
 		[],

cli/csstools-cli/src/plugins/postcss-media-queries-aspect-ratio-number-values.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-media-queries-aspect-ratio-number-values';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssMediaQueriesAspectRatioNumberValues() {
+export default function postcssMediaQueriesAspectRatioNumberValues(): void {
 	cli(
 		plugin,
 		[],

cli/csstools-cli/src/plugins/postcss-nested-calc.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-nested-calc';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssNestedCalc() {
+export default function postcssNestedCalc(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-nesting.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-nesting';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssNesting() {
+export default function postcssNesting(): void {
 	cli(
 		plugin,
 		['noIsPseudoSelector'],

cli/csstools-cli/src/plugins/postcss-normalize-display-values.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-normalize-display-values';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssNormalizeDisplayValues() {
+export default function postcssNormalizeDisplayValues(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-oklab-function.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-oklab-function';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssOKLabFunction() {
+export default function postcssOKLabFunction(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties', 'subFeatures'],

cli/csstools-cli/src/plugins/postcss-overflow-shorthand.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-overflow-shorthand';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssOverflowShorthand() {
+export default function postcssOverflowShorthand(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-place.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-place';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssPlace() {
+export default function postcssPlace(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-preset-env.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-preset-env';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssPresetEnv() {
+export default function postcssPresetEnv(): void {
 	cli(
 		plugin,
 		[

cli/csstools-cli/src/plugins/postcss-pseudo-class-any-link.ts

@@ -1,7 +1,7 @@
 import plugin from 'postcss-pseudo-class-any-link';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssPseudoClassAnyLink() {
+export default function postcssPseudoClassAnyLink(): void {
 	cli(
 		plugin,
 		['preserve'],

cli/csstools-cli/src/plugins/postcss-relative-color-syntax.ts

@@ -1,7 +1,7 @@
 import plugin from '@csstools/postcss-relative-color-syntax';
 import { cli, helpTextLogger } from '@csstools/base-cli';
 
-export default function postcssRelativeColorSyntax() {
+export default function postcssRelativeColorSyntax(): void {
 	cli(
 		plugin,
 		['preserve', 'enableProgressiveCustomProperties', 'subFeatures'],