[cfe] Pass on guard in if-case statement

Change-Id: Ic7c201bd90b2cf67a2b7526fc4ac035b21f34cc6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265720
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -2317,7 +2317,7 @@ class BodyBuilder extends StackListenerImpl
           libraryFeatures.patterns, case_.charOffset, case_.charCount);
       Matcher matcher = toMatcher(pop());
       Expression expression = popForValue();
-      push(new Condition(expression, matcher));
+      push(new Condition(expression, matcher, guard));
     } else {
       assert(checkState(token, [
         unionOfKinds([
@@ -3495,11 +3495,12 @@ class BodyBuilder extends StackListenerImpl
     Statement thenPart = popStatement();
     Condition condition = pop() as Condition;
     Matcher? matcher = condition.matcher;
+    Expression? guard = condition.guard;
     Expression expression = condition.expression;
     Statement node;
     if (matcher != null) {
       node = new IfCaseStatement(
-          expression, matcher, thenPart, elsePart, ifToken.charOffset);
+          expression, matcher, guard, thenPart, elsePart, ifToken.charOffset);
     } else {
       node = forest.createIfStatement(
           offsetForToken(ifToken), expression, thenPart, elsePart);
@@ -8809,10 +8810,14 @@ class _FindChildVisitor extends Visitor<void> with VisitorVoidMixin {
 class Condition {
   final Expression expression;
   final Matcher? matcher;
+  final Expression? guard;
 
-  Condition(this.expression, [this.matcher]);
+  Condition(this.expression, [this.matcher, this.guard])
+      : assert(guard == null || matcher != null,
+            "Unexpected guard without matcher.");
 
   @override
-  String toString() =>
-      'Condition($expression${matcher != null ? ',$matcher' : ''})';
+  String toString() => 'Condition($expression'
+      '${matcher != null ? ',$matcher' : ''}'
+      '${guard != null ? ',$guard' : ''})';
 }

pkg/front_end/lib/src/fasta/kernel/internal_ast.dart

@@ -5461,17 +5461,26 @@ class PatternVariableDeclaration extends Statement {
 
 final Matcher dummyMatcher = new ExpressionMatcher(dummyExpression);
 
+/// Internal statement for a if-case statements:
+///
+///     if (expression case matcher) then
+///     if (expression case matcher) then else otherwise
+///     if (expression case matcher when guard) then
+///     if (expression case matcher when guard) then else otherwise
+///
 class IfCaseStatement extends InternalStatement {
   Expression expression;
   Matcher matcher;
+  Expression? guard;
   Statement then;
   Statement? otherwise;
 
-  IfCaseStatement(this.expression, this.matcher, this.then, this.otherwise,
-      int fileOffset) {
+  IfCaseStatement(this.expression, this.matcher, this.guard, this.then,
+      this.otherwise, int fileOffset) {
     this.fileOffset = fileOffset;
     expression.parent = this;
     matcher.parent = this;
+    guard?.parent = this;
     then.parent = this;
     otherwise?.parent = this;
   }
@@ -5487,6 +5496,10 @@ class IfCaseStatement extends InternalStatement {
     printer.writeExpression(expression);
     printer.write(' case ');
     matcher.toTextInternal(printer);
+    if (guard != null) {
+      printer.write(' when ');
+      printer.writeExpression(guard!);
+    }
     printer.write(') ');
     printer.writeStatement(then);
     if (otherwise != null) {

pkg/front_end/lib/src/fasta/type_inference/inference_visitor.dart

@@ -1802,7 +1802,7 @@ class InferenceVisitorImpl extends InferenceVisitorBase
   }
 
   StatementInferenceResult visitIfCaseStatement(IfCaseStatement node) {
-    // TODO(cstefantsova): Handle if-case statements.
+    // TODO(cstefantsova): Handle if-case-when statements.
     return new StatementInferenceResult.single(
         new EmptyStatement()..fileOffset = node.fileOffset);
   }

pkg/front_end/test/text_representation/internal_ast_text_representation_test.dart

@@ -1144,6 +1144,7 @@ void _testIfCaseStatement() {
       new IfCaseStatement(
           new IntLiteral(0),
           new ExpressionMatcher(new IntLiteral(1)),
+          null,
           new ReturnStatement(),
           null,
           TreeNode.noOffset),
@@ -1154,9 +1155,32 @@ if (0 case 1) return;''');
       new IfCaseStatement(
           new IntLiteral(0),
           new ExpressionMatcher(new IntLiteral(1)),
+          null,
           new ReturnStatement(new IntLiteral(2)),
           new ReturnStatement(new IntLiteral(3)),
           TreeNode.noOffset),
       '''
 if (0 case 1) return 2; else return 3;''');
+
+  testStatement(
+      new IfCaseStatement(
+          new IntLiteral(0),
+          new ExpressionMatcher(new IntLiteral(1)),
+          new IntLiteral(2),
+          new ReturnStatement(),
+          null,
+          TreeNode.noOffset),
+      '''
+if (0 case 1 when 2) return;''');
+
+  testStatement(
+      new IfCaseStatement(
+          new IntLiteral(0),
+          new ExpressionMatcher(new IntLiteral(1)),
+          new IntLiteral(2),
+          new ReturnStatement(new IntLiteral(3)),
+          new ReturnStatement(new IntLiteral(4)),
+          TreeNode.noOffset),
+      '''
+if (0 case 1 when 2) return 3; else return 4;''');
 }

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart

@@ -0,0 +1,3 @@
+void f(x) {
+  if (x case 0 when true) {}
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.strong.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.strong.transformed.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.textual_outline.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.textual_outline_modelled.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.weak.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.weak.modular.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.weak.outline.expect

@@ -0,0 +1,5 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void
+  ;

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideIfStatement.dart.weak.transformed.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart

@@ -0,0 +1,6 @@
+void f(x) {
+  switch (x) {
+    case 0 when true:
+      break;
+  }
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.strong.expect

@@ -0,0 +1,18 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = 0
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.strong.transformed.expect

@@ -0,0 +1,18 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = 0
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.textual_outline.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.textual_outline_modelled.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.weak.expect

@@ -0,0 +1,18 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = 0
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.weak.modular.expect

@@ -0,0 +1,18 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = 0
+}

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.weak.outline.expect

@@ -0,0 +1,5 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void
+  ;

pkg/front_end/testcases/patterns/caseHead_withClassicPattern_guarded_insideSwitchStatement.dart.weak.transformed.expect

@@ -0,0 +1,18 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = 0
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart

@@ -0,0 +1,3 @@
+void f(x) {
+  if (x case 0 as int when true) {}
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.strong.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.strong.transformed.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.textual_outline.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.textual_outline_modelled.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.weak.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.weak.modular.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.weak.outline.expect

@@ -0,0 +1,5 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void
+  ;

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideIfStatement.dart.weak.transformed.expect

@@ -0,0 +1,6 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  ;
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart

@@ -0,0 +1,6 @@
+void f(x) {
+  switch (x) {
+    case 0 as int when true:
+      break;
+  }
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.strong.expect

@@ -0,0 +1,17 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.strong.transformed.expect

@@ -0,0 +1,17 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.textual_outline.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.textual_outline_modelled.expect

@@ -0,0 +1 @@
+void f(x) {}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.weak.expect

@@ -0,0 +1,17 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.weak.modular.expect

@@ -0,0 +1,17 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = null
+}

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.weak.outline.expect

@@ -0,0 +1,5 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void
+  ;

pkg/front_end/testcases/patterns/caseHead_withNewPattern_guarded_insideSwitchStatement.dart.weak.transformed.expect

@@ -0,0 +1,17 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+static method f(dynamic x) → void {
+  #L1:
+  switch(x) {
+    #L2:
+    case #C1:
+      {
+        break #L1;
+      }
+  }
+}
+
+constants  {
+  #C1 = null
+}