move migrate-drop-unnecessary-data-types to core

packages/@tailwindcss-upgrade/src/codemods/template/migrate.ts

@@ -11,7 +11,6 @@ import { migrateArbitraryValueToBareValue } from './migrate-arbitrary-value-to-b
 import { migrateAutomaticVarInjection } from './migrate-automatic-var-injection'
 import { migrateCamelcaseInNamedValue } from './migrate-camelcase-in-named-value'
 import { migrateCanonicalizeCandidate } from './migrate-canonicalize-candidate'
-import { migrateDropUnnecessaryDataTypes } from './migrate-drop-unnecessary-data-types'
 import { migrateEmptyArbitraryValues } from './migrate-handle-empty-arbitrary-values'
 import { migrateLegacyArbitraryValues } from './migrate-legacy-arbitrary-values'
 import { migrateLegacyClasses } from './migrate-legacy-classes'
@@ -40,7 +39,6 @@ export const DEFAULT_MIGRATIONS: Migration[] = [
   migrateAutomaticVarInjection, // sync, v3 → v4
   migrateLegacyArbitraryValues, // sync, v3 → v4 (could also consider it a v4 optimization)
   migrateModernizeArbitraryValues, // sync, v3 and v4 optimizations, split up?
-  migrateDropUnnecessaryDataTypes, // sync, v4 (I think this can be dropped?)
   migrateArbitraryValueToBareValue, // sync, v4 (optimization)
   migrateOptimizeModifier, // sync, v4 (optimization)
 ]

packages/tailwindcss/src/canonicalize-candidates.test.ts

@@ -637,6 +637,29 @@ describe.each([['default'], ['with-variant'], ['important'], ['prefix']])('%s',
       await expectCanonicalization(input, candidate, expected)
     })
   })
+
+  describe('drop unnecessary data types', () => {
+    let input = css`
+      @import 'tailwindcss';
+      @theme {
+        --*: initial;
+        --color-red-500: red;
+      }
+    `
+
+    test.each([
+      // A color value can be inferred from the value
+      ['bg-[color:#008cc]', 'bg-[#008cc]'],
+
+      // A color is the default for `bg-*`
+      ['bg-(color:--my-value)', 'bg-(--my-value)'],
+
+      // A color with a known theme variable migrates to the full utility
+      ['bg-(color:--color-red-500)', 'bg-red-500'],
+    ])(testName, async (candidate, expected) => {
+      await expectCanonicalization(input, candidate, expected)
+    })
+  })
 })
 
 describe('theme to var', () => {

packages/tailwindcss/src/canonicalize-candidates.ts

@@ -44,6 +44,7 @@ const CANONICALIZATIONS = [
   bareValueUtilities,
   deprecatedUtilities,
   arbitraryVariants,
+  dropUnnecessaryDataTypes,
   print,
 ]
 
@@ -909,3 +910,28 @@ function arbitraryVariants(designSystem: DesignSystem, rawCandidate: string): st
 
   return rawCandidate
 }
+
+// ----
+
+function dropUnnecessaryDataTypes(designSystem: DesignSystem, rawCandidate: string): string {
+  let signatures = computeUtilitySignature.get(designSystem)
+
+  for (let candidate of designSystem.parseCandidate(rawCandidate)) {
+    if (
+      candidate.kind === 'functional' &&
+      candidate.value?.kind === 'arbitrary' &&
+      candidate.value.dataType !== null
+    ) {
+      let replacement = designSystem.printCandidate({
+        ...candidate,
+        value: { ...candidate.value, dataType: null },
+      })
+
+      if (signatures.get(rawCandidate) === signatures.get(replacement)) {
+        return replacement
+      }
+    }
+  }
+
+  return rawCandidate
+}