Add support for the plain CSS type() function (#2630)

Closes #2539

Author: nex3

CHANGELOG.md

@@ -4,6 +4,11 @@
   the order they appear in the source even when they're interleaved with nested
   rules. This obsoletes the `mixed-decls` deprecation.
 
+* **Breaking change:** The function name `type()` is now fully reserved for the
+  plain CSS function. This means that `@function` definitions with the name
+  `type` will produce errors, while function calls will be parsed as special
+  function strings.
+
 * Fix a bug where `@extend` rules loaded through a mixture of `@import` and
   `@use` rules could fail to apply correctly.
 

lib/src/deprecation.dart

@@ -15,7 +15,7 @@ enum Deprecation {
   // DO NOT EDIT. This section was generated from the language repo.
   // See tool/grind/generate_deprecations.dart for details.
   //
-  // Checksum: 2a2a94a3dd8ab2f7e3880b24e8e7850d66998b33
+  // Checksum: 247ee9ef1df8665b759064856492831661b08985
 
   /// Deprecation for passing a string directly to meta.call().
   callString('call-string',
@@ -125,7 +125,9 @@ enum Deprecation {
 
   /// Deprecation for functions named "type".
   typeFunction('type-function',
-      deprecatedIn: '1.86.0', description: 'Functions named "type".'),
+      deprecatedIn: '1.86.0',
+      obsoleteIn: '1.92.0',
+      description: 'Functions named "type".'),
 
   /// Deprecation for passing a relative url to compileString().
   compileStringRelativeUrl('compile-string-relative-url',

lib/src/parse/stylesheet.dart

@@ -932,14 +932,8 @@ abstract class StylesheetParser extends Parser {
         span: scanner.spanFrom(beforeName),
       ));
     } else if (equalsIgnoreCase(name, 'type')) {
-      warnings.add((
-        deprecation: Deprecation.typeFunction,
-        message: 'Sass @functions named "type" are deprecated for forward-'
-            'compatibility with the plain CSS type() function.\n'
-            '\n'
-            'For details, see https://sass-lang.com/d/type-function',
-        span: scanner.spanFrom(beforeName),
-      ));
+      error('This name is reserved for the plain-CSS function.',
+          scanner.spanFrom(beforeName));
     }
 
     whitespace(consumeNewlines: true);
@@ -2966,35 +2960,40 @@ abstract class StylesheetParser extends Parser {
   /// [name].
   @protected
   Expression? trySpecialFunction(String name, LineScannerState start) {
-    var normalized = unvendor(name);
-
     InterpolationBuffer buffer;
-    switch (normalized) {
-      case "calc" when normalized != name && scanner.scanChar($lparen):
-      case "element" || "expression" when scanner.scanChar($lparen):
-        buffer = InterpolationBuffer()
-          ..write(name)
-          ..writeCharCode($lparen);
-
-      case "progid" when scanner.scanChar($colon):
-        buffer = InterpolationBuffer()
-          ..write(name)
-          ..writeCharCode($colon);
-        var next = scanner.peekChar();
-        while (next != null && (next.isAlphabetic || next == $dot)) {
-          buffer.writeCharCode(scanner.readChar());
-          next = scanner.peekChar();
-        }
-        scanner.expectChar($lparen);
-        buffer.writeCharCode($lparen);
+    if (name == "type" && scanner.scanChar($lparen)) {
+      buffer = InterpolationBuffer()
+        ..write(name)
+        ..writeCharCode($lparen);
+    } else {
+      var normalized = unvendor(name);
+      switch (normalized) {
+        case "calc" when normalized != name && scanner.scanChar($lparen):
+        case "element" || "expression" when scanner.scanChar($lparen):
+          buffer = InterpolationBuffer()
+            ..write(name)
+            ..writeCharCode($lparen);
+
+        case "progid" when scanner.scanChar($colon):
+          buffer = InterpolationBuffer()
+            ..write(name)
+            ..writeCharCode($colon);
+          var next = scanner.peekChar();
+          while (next != null && (next.isAlphabetic || next == $dot)) {
+            buffer.writeCharCode(scanner.readChar());
+            next = scanner.peekChar();
+          }
+          scanner.expectChar($lparen);
+          buffer.writeCharCode($lparen);
 
-      case "url":
-        return _tryUrlContents(
-          start,
-        ).andThen((contents) => StringExpression(contents));
+        case "url":
+          return _tryUrlContents(
+            start,
+          ).andThen((contents) => StringExpression(contents));
 
-      case _:
-        return null;
+        case _:
+          return null;
+      }
     }
 
     buffer.addInterpolation(_interpolatedDeclarationValue(allowEmpty: true));