Update to PostCSS 8.

packages/next/build/webpack/config/blocks/css/loaders/global.ts

@@ -1,12 +1,12 @@
-import postcss from 'postcss'
+import { AcceptedPlugin } from 'postcss'
 import webpack from 'webpack'
 import { ConfigurationContext } from '../../../utils'
 import { getClientStyleLoader } from './client'
 import { cssFileResolve } from './file-resolve'
 
 export function getGlobalCssLoader(
   ctx: ConfigurationContext,
-  postCssPlugins: readonly postcss.AcceptedPlugin[],
+  postCssPlugins: readonly AcceptedPlugin[],
   preProcessors: readonly webpack.RuleSetUseItem[] = []
 ): webpack.RuleSetUseItem[] {
   const loaders: webpack.RuleSetUseItem[] = []

packages/next/build/webpack/config/blocks/css/loaders/modules.ts

@@ -1,4 +1,4 @@
-import postcss from 'postcss'
+import { AcceptedPlugin } from 'postcss'
 import webpack from 'webpack'
 import { ConfigurationContext } from '../../../utils'
 import { getClientStyleLoader } from './client'
@@ -7,7 +7,7 @@ import { getCssModuleLocalIdent } from './getCssModuleLocalIdent'
 
 export function getCssModuleLoader(
   ctx: ConfigurationContext,
-  postCssPlugins: readonly postcss.AcceptedPlugin[],
+  postCssPlugins: readonly AcceptedPlugin[],
   preProcessors: readonly webpack.RuleSetUseItem[] = []
 ): webpack.RuleSetUseItem[] {
   const loaders: webpack.RuleSetUseItem[] = []

packages/next/build/webpack/plugins/css-minimizer-plugin.ts

@@ -1,4 +1,5 @@
-import { process as minify } from 'cssnano-simple'
+import cssnanoSimple from 'cssnano-simple'
+import postcss from 'postcss'
 import webpack from 'webpack'
 import sources from 'webpack-sources'
 
@@ -41,13 +42,15 @@ export class CssMinimizerPlugin {
       input = asset.source()
     }
 
-    return minify(input, postcssOptions).then((res) => {
-      if (res.map) {
-        return new SourceMapSource(res.css, file, res.map.toJSON())
-      } else {
-        return new RawSource(res.css)
-      }
-    })
+    return postcss([cssnanoSimple])
+      .process(input, postcssOptions)
+      .then((res) => {
+        if (res.map) {
+          return new SourceMapSource(res.css, file, res.map.toJSON())
+        } else {
+          return new RawSource(res.css)
+        }
+      })
   }
 
   apply(compiler: webpack.Compiler) {

packages/next/package.json

@@ -103,7 +103,7 @@
     "node-html-parser": "^1.2.19",
     "path-browserify": "1.0.1",
     "pnp-webpack-plugin": "1.6.4",
-    "postcss": "7.0.32",
+    "postcss": "8.1.1",
     "process": "0.11.10",
     "prop-types": "15.7.2",
     "react-is": "16.13.1",

packages/next/types/misc.d.ts

@@ -3,8 +3,8 @@ declare module '@babel/plugin-transform-modules-commonjs'
 declare module '@babel/plugin-syntax-jsx'
 declare module 'browserslist'
 declare module 'cssnano-simple' {
-  import { Plugin } from 'postcss'
-  const cssnanoSimple: Plugin<{}>
+  import { OldPlugin } from 'postcss'
+  const cssnanoSimple: OldPlugin<{}>
   export = cssnanoSimple
 }
 declare module 'styled-jsx/server'

yarn.lock

@@ -5396,6 +5396,11 @@ color@^3.1.2:
     color-convert "^1.9.1"
     color-string "^1.5.4"
 
+colorette@^1.2.1:
+  version "1.2.1"
+  resolved "https://registry.yarnpkg.com/colorette/-/colorette-1.2.1.tgz#4d0b921325c14faf92633086a536db6e89564b1b"
+  integrity sha512-puCDz0CzydiSYOrnXpz/PKd69zRrribezjtE9yd4zvytoRc8+RY/KJPvtPFKZS3E3wP6neGyMe0vOTlHO5L3Pw==
+
 colormin@^1.0.5:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/colormin/-/colormin-1.1.2.tgz#ea2f7420a72b96881a38aae59ec124a6f7298133"
@@ -10410,6 +10415,14 @@ limit-spawn@0.0.3:
   version "0.0.3"
   resolved "https://registry.yarnpkg.com/limit-spawn/-/limit-spawn-0.0.3.tgz#cc09c24467a0f0a1ed10a5196dba597cad3f65dc"
 
+line-column@^1.0.2:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/line-column/-/line-column-1.0.2.tgz#d25af2936b6f4849172b312e4792d1d987bc34a2"
+  integrity sha1-0lryk2tvSEkXKzEuR5LR2Ye8NKI=
+  dependencies:
+    isarray "^1.0.0"
+    isobject "^2.0.0"
+
 lines-and-columns@^1.1.6:
   version "1.1.6"
   resolved "https://registry.yarnpkg.com/lines-and-columns/-/lines-and-columns-1.1.6.tgz#1c00c743b433cd0a4e80758f7b64a57440d9ff00"
@@ -11429,6 +11442,11 @@ nanoid@2.0.3:
   version "2.0.3"
   resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-2.0.3.tgz#dde999e173bc9d7bd2ee2746b89909ade98e075e"
 
+nanoid@^3.1.12:
+  version "3.1.12"
+  resolved "https://registry.yarnpkg.com/nanoid/-/nanoid-3.1.12.tgz#6f7736c62e8d39421601e4a0c77623a97ea69654"
+  integrity sha512-1qstj9z5+x491jfiC4Nelk+f8XBad7LN20PmyWINJEMRSf3wcAjAWysw1qaA8z6NSKe2sjq1hRSDpBH5paCb6A==
+
 nanomatch@^1.2.9:
   version "1.2.13"
   resolved "https://registry.yarnpkg.com/nanomatch/-/nanomatch-1.2.13.tgz#b87a8aa4fc0de8fe6be88895b38983ff265bd119"
@@ -13541,6 +13559,16 @@ postcss@7.0.32, postcss@^7.0.32:
     source-map "^0.6.1"
     supports-color "^6.1.0"
 
+postcss@8.1.1:
+  version "8.1.1"
+  resolved "https://registry.yarnpkg.com/postcss/-/postcss-8.1.1.tgz#c3a287dd10e4f6c84cb3791052b96a5d859c9389"
+  integrity sha512-9DGLSsjooH3kSNjTZUOt2eIj2ZTW0VI2PZ/3My+8TC7KIbH2OKwUlISfDsf63EP4aiRUt3XkEWMWvyJHvJelEg==
+  dependencies:
+    colorette "^1.2.1"
+    line-column "^1.0.2"
+    nanoid "^3.1.12"
+    source-map "^0.6.1"
+
 postcss@^5.0.10, postcss@^5.0.11, postcss@^5.0.12, postcss@^5.0.13, postcss@^5.0.14, postcss@^5.0.16, postcss@^5.0.2, postcss@^5.0.4, postcss@^5.0.5, postcss@^5.0.8, postcss@^5.2.16:
   version "5.2.18"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-5.2.18.tgz#badfa1497d46244f6390f58b319830d9107853c5"