revert @import layer(…) handling main CSS handler

packages/tailwindcss/src/index.test.ts

@@ -3047,11 +3047,11 @@ test('addBase', async () => {
   `)
 })
 
-it('should error when `layer(…)` is not the first param', async () => {
+it("should error when `layer(…)` is used, but it's not the first param", async () => {
   expect(async () => {
     return await compileCss(
       css`
-        @import './bar.css' source(--foo) layer(utilities);
+        @import './bar.css' supports(display: grid) layer(utilities);
       `,
       [],
       {
@@ -3067,49 +3067,7 @@ it('should error when `layer(…)` is not the first param', async () => {
         },
       },
     )
-  }).rejects.toThrowErrorMatchingInlineSnapshot(`
-    [Error: A \`layer(…)\` in an \`@import\` should come first:
-
-    \`\`\`diff
-    - @import './bar.css' source(--foo) layer(utilities);
-    + @import './bar.css' layer(utilities) source(--foo);
-    \`\`\`]
-  `)
-})
-
-it('should error when `layer(…)` is part of an `@media`', async () => {
-  expect(
-    async () =>
-      await compileCss(css`
-        @media layer(utilities) {
-          .foo {
-            color: red;
-            @media layer(other) {
-              .bar {
-                color: blue;
-              }
-            }
-          }
-        }
-      `),
-  ).rejects.toThrowErrorMatchingInlineSnapshot(
-    `
-    [Error: A \`@media layer(…)\` is invalid, did you mean to use \`@layer\`?
-
-    \`\`\`css
-    - @media layer(utilities) {
-    + @layer utilities {
-        .foo {
-          color: red;
-    -     @media layer(other) {
-    +     @layer other {
-            .bar {
-              color: blue;
-            }
-          }
-        }
-      }
-    \`\`\`]
-  `,
+  }).rejects.toThrowErrorMatchingInlineSnapshot(
+    `[Error: \`layer(…)\` in an \`@import\` should come before any other functions or conditions]`,
   )
 })

packages/tailwindcss/src/index.ts

@@ -337,77 +337,6 @@ async function parseCss(
           important = true
         }
 
-        // Handle `layer(…)`
-        else if (param.startsWith('layer(')) {
-          // Whenever we see an `@media layer(…)`, it means one of two things:
-          //
-          // 1. Somebody added a manual `@media layer(…)` rule, which is not
-          //    supported.
-          // 2. Somebody used an `@import 'url' something(else) layer(…)` rule,
-          //    which is not supported by spec because a `layer(…)` has to be
-          //    first.
-
-          // It was an `@import layer(…)`
-          if (node.nodes?.[0]?.kind === 'context') {
-            let actual = node.nodes[0].context.source.trim().slice(0, -1)
-            let expected = segment(actual, ' ')
-            let layer = expected.findIndex((part) => part.startsWith('layer('))
-            expected.splice(2, 0, ...expected.splice(layer, 1))
-
-            let errorMessage = [
-              '`layer(…)` in an `@import` should come before any other functions or conditions:',
-              '',
-              '```diff',
-              `- ${actual};`,
-              `+ ${expected.join(' ')};`,
-              '```',
-            ].join('\n')
-
-            throw new Error(errorMessage)
-          }
-
-          // It was an `@media layer(…)`
-          else {
-            let afterNode = structuredClone(node)
-            let afterAst = [afterNode]
-            walk(afterAst, (node, { replaceWith }) => {
-              if (
-                node.kind === 'at-rule' &&
-                node.name === '@media' &&
-                node.params.includes('layer(')
-              ) {
-                let layer = segment(node.params, ' ')
-                  .find((part) => part.startsWith('layer('))
-                  ?.slice(6, -1)
-                replaceWith(atRule('@layer', layer, node.nodes))
-              }
-            })
-
-            let beforeLines = toCss([node]).trim().split('\n')
-            let afterLines = toCss(afterAst).trim().split('\n')
-
-            let lines = []
-            for (let i = beforeLines.length - 1; i >= 0; i--) {
-              if (beforeLines[i] !== afterLines[i]) {
-                lines.unshift(`+ ${afterLines[i]}`)
-                lines.unshift(`- ${beforeLines[i]}`)
-              } else {
-                lines.unshift(`  ${beforeLines[i]}`)
-              }
-            }
-
-            let errorMessage = [
-              'A `@media layer(…)` is invalid, did you mean to use `@layer`?',
-              '',
-              '```css',
-              ...lines,
-              '```',
-            ].join('\n')
-
-            throw new Error(errorMessage)
-          }
-        }
-
         //
         else {
           unknownParams.push(param)