Fix negative utility generation and detection when using a prefix

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Correctly parse shadow lengths without a leading zero ([#7289](https://github.com/tailwindlabs/tailwindcss/pull/7289))
 - Don't crash when scanning extremely long class candidates ([#7331](https://github.com/tailwindlabs/tailwindcss/pull/7331))
 - Use less hacky fix for urls detected as custom properties ([#7275](https://github.com/tailwindlabs/tailwindcss/pull/7275))
+- Correctly generate negative utilities when dash is before the prefix ([#7295](https://github.com/tailwindlabs/tailwindcss/pull/7295))
+- Detect prefixed negative utilities in the safelist ([#7295](https://github.com/tailwindlabs/tailwindcss/pull/7295))
 
 ## [3.0.18] - 2022-01-28
 

src/lib/generateRules.js

@@ -63,9 +63,23 @@ function applyPrefix(matches, context) {
     let [meta] = match
     if (meta.options.respectPrefix) {
       let container = postcss.root({ nodes: [match[1].clone()] })
+      let classCandidate = match[1].raws.tailwind.classCandidate
+
       container.walkRules((r) => {
-        r.selector = prefixSelector(context.tailwindConfig.prefix, r.selector)
+        // If this is a negative utility with a dash *before* the prefix we
+        // have to ensure that the generated selector matches the candidate
+
+        // Not doing this will cause `-tw-top-1` to generate the class `.tw--top-1`
+        // The disconnect between candidate <-> class can cause @apply to hard crash.
+        let shouldPrependNegative = classCandidate.startsWith('-')
+
+        r.selector = prefixSelector(
+          context.tailwindConfig.prefix,
+          r.selector,
+          shouldPrependNegative
+        )
       })
+
       match[1] = container.nodes[0]
     }
   }
@@ -371,6 +385,14 @@ function splitWithSeparator(input, separator) {
   return input.split(new RegExp(`\\${separator}(?![^[]*\\])`, 'g'))
 }
 
+function* recordCandidates(matches, classCandidate) {
+  for (const match of matches) {
+    match[1].raws.tailwind = { classCandidate }
+
+    yield match
+  }
+}
+
 function* resolveMatches(candidate, context) {
   let separator = context.tailwindConfig.separator
   let [classCandidate, ...variants] = splitWithSeparator(candidate, separator).reverse()
@@ -482,7 +504,9 @@ function* resolveMatches(candidate, context) {
       continue
     }
 
-    matches = applyPrefix(matches.flat(), context)
+    matches = matches.flat()
+    matches = Array.from(recordCandidates(matches, classCandidate))
+    matches = applyPrefix(matches, context)
 
     if (important) {
       matches = applyImportant(matches, context)

src/lib/setupContextUtils.js

@@ -666,17 +666,30 @@ function registerPlugins(plugins, context) {
 
     if (checks.length > 0) {
       let patternMatchingCount = new Map()
+      let prefixLength = context.tailwindConfig.prefix.length
 
       for (let util of classList) {
         let utils = Array.isArray(util)
           ? (() => {
               let [utilName, options] = util
-              let classes = Object.keys(options?.values ?? {}).map((value) =>
-                formatClass(utilName, value)
-              )
+              let values = Object.keys(options?.values ?? {})
+              let classes = values.map((value) => formatClass(utilName, value))
 
               if (options?.supportsNegativeValues) {
+                // This is the normal negated version
+                // e.g. `-inset-1` or `-tw-inset-1`
                 classes = [...classes, ...classes.map((cls) => '-' + cls)]
+
+                // This is the negated version *after* the prefix
+                // e.g. `tw--inset-1`
+                // The prefix is already attached to util name
+                // So we add the negative after the prefix
+                classes = [
+                  ...classes,
+                  ...classes.map(
+                    (cls) => cls.slice(0, prefixLength) + '-' + cls.slice(prefixLength)
+                  ),
+                ]
               }
 
               return classes

src/util/prefixSelector.js

@@ -1,12 +1,14 @@
 import parser from 'postcss-selector-parser'
-import { tap } from './tap'
 
-export default function (prefix, selector) {
+export default function (prefix, selector, prependNegative = false) {
   return parser((selectors) => {
     selectors.walkClasses((classSelector) => {
-      tap(classSelector.value, (baseClass) => {
-        classSelector.value = `${prefix}${baseClass}`
-      })
+      let baseClass = classSelector.value
+      let shouldPlaceNegativeBeforePrefix = prependNegative && baseClass.startsWith('-')
+
+      classSelector.value = shouldPlaceNegativeBeforePrefix
+        ? `-${prefix}${baseClass.slice(1)}`
+        : `${prefix}${baseClass}`
     })
   }).processSync(selector)
 }

tests/getClassList.test.js

@@ -5,22 +5,57 @@ it('should generate every possible class, without variants', () => {
   let config = {}
 
   let context = createContext(resolveConfig(config))
-  expect(context.getClassList()).toBeInstanceOf(Array)
+  let classes = context.getClassList()
+  expect(classes).toBeInstanceOf(Array)
 
   // Verify we have a `container` for the 'components' section.
-  expect(context.getClassList()).toContain('container')
+  expect(classes).toContain('container')
 
   // Verify we handle the DEFAULT case correctly
-  expect(context.getClassList()).toContain('border')
+  expect(classes).toContain('border')
 
   // Verify we handle negative values correctly
-  expect(context.getClassList()).toContain('-inset-1/4')
-  expect(context.getClassList()).toContain('-m-0')
-  expect(context.getClassList()).not.toContain('-uppercase')
-  expect(context.getClassList()).not.toContain('-opacity-50')
-  expect(
-    createContext(
-      resolveConfig({ theme: { extend: { margin: { DEFAULT: '5px' } } } })
-    ).getClassList()
-  ).not.toContain('-m-DEFAULT')
+  expect(classes).toContain('-inset-1/4')
+  expect(classes).toContain('-m-0')
+  expect(classes).not.toContain('-uppercase')
+  expect(classes).not.toContain('-opacity-50')
+
+  config = { theme: { extend: { margin: { DEFAULT: '5px' } } } }
+  context = createContext(resolveConfig(config))
+  classes = context.getClassList()
+
+  expect(classes).not.toContain('-m-DEFAULT')
+})
+
+it('should generate every possible class while handling negatives and prefixes', () => {
+  let config = { prefix: 'tw-' }
+  let context = createContext(resolveConfig(config))
+  let classes = context.getClassList()
+  expect(classes).toBeInstanceOf(Array)
+
+  // Verify we have a `container` for the 'components' section.
+  expect(classes).toContain('tw-container')
+
+  // Verify we handle the DEFAULT case correctly
+  expect(classes).toContain('tw-border')
+
+  // Verify we handle negative values correctly
+  expect(classes).toContain('-tw-inset-1/4')
+  expect(classes).toContain('-tw-m-0')
+  expect(classes).not.toContain('-tw-uppercase')
+  expect(classes).not.toContain('-tw-opacity-50')
+
+  // These utilities do work but there's no reason to generate
+  // them alongside the `-{prefix}-{utility}` versions
+  expect(classes).not.toContain('tw--inset-1/4')
+  expect(classes).not.toContain('tw--m-0')
+
+  config = {
+    prefix: 'tw-',
+    theme: { extend: { margin: { DEFAULT: '5px' } } },
+  }
+  context = createContext(resolveConfig(config))
+  classes = context.getClassList()
+
+  expect(classes).not.toContain('-tw-m-DEFAULT')
 })