Emergency fix: Temporarily drop support for min/max calculations (#1477)

See sass/sass#3142
See sass/sass-spec#1702

Author: nex3

CHANGELOG.md

@@ -1,3 +1,17 @@
+## 1.40.1
+
+* **Potentially breaking bug fix:** `min()` and `max()` expressions outside of
+  calculations now behave the same way they did in 1.39.2, returning unquoted
+  strings if they contain no Sass-specific features and calling the global
+  `min()` and `max()` functions otherwise. Within calculations, they continue to
+  behave how they did in 1.40.0.
+
+  This fixes an unintended breaking change added in 1.40.0, wherein passing a
+  unitless number and a number without units to `min()` or `max()` now produces
+  an error. Since this breakage affects a major Sass library, we're temporarily
+  reverting support for `min()` and `max()` calculations while we work on
+  designing a longer-term fix.
+
 ## 1.40.0
 
 * Add support for first-class `calc()` expressions (as well as `clamp()` and

lib/src/parse/stylesheet.dart

@@ -2714,6 +2714,25 @@ abstract class StylesheetParser extends Parser {
           ..writeCharCode($lparen);
         break;
 
+      case "min":
+      case "max":
+        // min() and max() are parsed as the plain CSS mathematical functions if
+        // possible, and otherwise are parsed as normal Sass functions.
+        var beginningOfContents = scanner.state;
+        if (!scanner.scanChar($lparen)) return null;
+        whitespace();
+
+        var buffer = InterpolationBuffer()
+          ..write(name)
+          ..writeCharCode($lparen);
+
+        if (!_tryMinMaxContents(buffer)) {
+          scanner.state = beginningOfContents;
+          return null;
+        }
+
+        return StringExpression(buffer.interpolation(scanner.spanFrom(start)));
+
       case "progid":
         if (!scanner.scanChar($colon)) return null;
         buffer = InterpolationBuffer()
@@ -2748,7 +2767,11 @@ abstract class StylesheetParser extends Parser {
   ///
   /// Assumes the scanner is positioned immediately before the opening
   /// parenthesis of the argument list.
-  CalculationExpression? _tryCalculation(String name, LineScannerState start) {
+  ///
+  /// If [allowMinMax] is `true`, this parses `min()` and `max()` functions as
+  /// calculations.
+  CalculationExpression? _tryCalculation(String name, LineScannerState start,
+      {bool allowMinMax = false}) {
     assert(scanner.peekChar() == $lparen);
     switch (name) {
       case "calc":
@@ -2757,18 +2780,9 @@ abstract class StylesheetParser extends Parser {
 
       case "min":
       case "max":
-        // min() and max() are parsed as calculations if possible, and otherwise
-        // are parsed as normal Sass functions.
-        var beforeArguments = scanner.state;
-        List<Expression> arguments;
-        try {
-          arguments = _calculationArguments();
-        } on FormatException catch (_) {
-          scanner.state = beforeArguments;
-          return null;
-        }
-
-        return CalculationExpression(name, arguments, scanner.spanFrom(start));
+        if (!allowMinMax) return null;
+        return CalculationExpression(
+            name, _calculationArguments(), scanner.spanFrom(start));
 
       case "clamp":
         var arguments = _calculationArguments(3);
@@ -2779,6 +2793,142 @@ abstract class StylesheetParser extends Parser {
     }
   }
 
+  /// Consumes the contents of a plain-CSS `min()` or `max()` function into
+  /// [buffer] if one is available.
+  ///
+  /// Returns whether this succeeded.
+  ///
+  /// If [allowComma] is `true` (the default), this allows `CalcValue`
+  /// productions separated by commas.
+  bool _tryMinMaxContents(InterpolationBuffer buffer,
+      {bool allowComma = true}) {
+    // The number of open parentheses that need to be closed.
+    while (true) {
+      var next = scanner.peekChar();
+      switch (next) {
+        case $minus:
+        case $plus:
+        case $0:
+        case $1:
+        case $2:
+        case $3:
+        case $4:
+        case $5:
+        case $6:
+        case $7:
+        case $8:
+        case $9:
+        case $dot:
+          try {
+            buffer.write(rawText(_number));
+          } on FormatException catch (_) {
+            return false;
+          }
+          break;
+
+        case $hash:
+          if (scanner.peekChar(1) != $lbrace) return false;
+          buffer.add(singleInterpolation());
+          break;
+
+        case $c:
+        case $C:
+          switch (scanner.peekChar(1)) {
+            case $a:
+            case $A:
+              if (!_tryMinMaxFunction(buffer, "calc")) return false;
+              break;
+
+            case $l:
+            case $L:
+              if (!_tryMinMaxFunction(buffer, "clamp")) return false;
+              break;
+          }
+          break;
+
+        case $e:
+        case $E:
+          if (!_tryMinMaxFunction(buffer, "env")) return false;
+          break;
+
+        case $v:
+        case $V:
+          if (!_tryMinMaxFunction(buffer, "var")) return false;
+          break;
+
+        case $lparen:
+          buffer.writeCharCode(scanner.readChar());
+          if (!_tryMinMaxContents(buffer, allowComma: false)) return false;
+          break;
+
+        case $m:
+        case $M:
+          scanner.readChar();
+          if (scanIdentChar($i)) {
+            if (!scanIdentChar($n)) return false;
+            buffer.write("min(");
+          } else if (scanIdentChar($a)) {
+            if (!scanIdentChar($x)) return false;
+            buffer.write("max(");
+          } else {
+            return false;
+          }
+          if (!scanner.scanChar($lparen)) return false;
+
+          if (!_tryMinMaxContents(buffer)) return false;
+          break;
+
+        default:
+          return false;
+      }
+
+      whitespace();
+
+      next = scanner.peekChar();
+      switch (next) {
+        case $rparen:
+          buffer.writeCharCode(scanner.readChar());
+          return true;
+
+        case $plus:
+        case $minus:
+        case $asterisk:
+        case $slash:
+          buffer.writeCharCode($space);
+          buffer.writeCharCode(scanner.readChar());
+          buffer.writeCharCode($space);
+          break;
+
+        case $comma:
+          if (!allowComma) return false;
+          buffer.writeCharCode(scanner.readChar());
+          buffer.writeCharCode($space);
+          break;
+
+        default:
+          return false;
+      }
+
+      whitespace();
+    }
+  }
+
+  /// Consumes a function named [name] containing an
+  /// `InterpolatedDeclarationValue` if possible, and adds its text to [buffer].
+  ///
+  /// Returns whether such a function could be consumed.
+  bool _tryMinMaxFunction(InterpolationBuffer buffer, String name) {
+    if (!scanIdentifier(name)) return false;
+    if (!scanner.scanChar($lparen)) return false;
+    buffer
+      ..write(name)
+      ..writeCharCode($lparen)
+      ..addInterpolation(_interpolatedDeclarationValue(allowEmpty: true))
+      ..writeCharCode($rparen);
+    if (!scanner.scanChar($rparen)) return false;
+    return true;
+  }
+
   /// Consumes and returns arguments for a calculation expression, including the
   /// opening and closing parentheses.
   ///
@@ -2876,7 +3026,7 @@ abstract class StylesheetParser extends Parser {
       if (scanner.peekChar() != $lparen) scanner.error('Expected "(" or ".".');
 
       var lowerCase = ident.toLowerCase();
-      var calculation = _tryCalculation(lowerCase, start);
+      var calculation = _tryCalculation(lowerCase, start, allowMinMax: true);
       if (calculation != null) {
         return calculation;
       } else if (lowerCase == "if") {

pkg/sass_api/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.0-beta.10
+
+* No user-visible changes.
+
 ## 1.0.0-beta.9
 
 * Add the `CalculationExpression` type to represent calculations in the Sass

pkg/sass_api/pubspec.yaml

@@ -2,15 +2,15 @@ name: sass_api
 # Note: Every time we add a new Sass AST node, we need to bump the *major*
 # version because it's a breaking change for anyone who's implementing the
 # visitor interface(s).
-version: 1.0.0-beta.9
+version: 1.0.0-beta.10
 description: Additional APIs for Dart Sass.
 homepage: https://github.com/sass/dart-sass
 
 environment:
   sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
-  sass: 1.40.0
+  sass: 1.40.1
 
 dependency_overrides:
   sass: {path: ../..}

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.40.0
+version: 1.40.1
 description: A Sass implementation in Dart.
 homepage: https://github.com/sass/dart-sass