Infer types of bool/null/string literals.

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

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This file declares a "shadow hierarchy" of concrete classes which extend
 /// the kernel class hierarchy, adding methods and fields needed by the
 /// BodyBuilder.
 ///
 /// Instances of these classes may be created using the factory methods in
 /// `ast_factory.dart`.
@@ skipping 17 matching lines @@
   KernelBlock(List<Statement> statements) : super(statements);
 
   @override
   void _inferStatement(KernelTypeInferrer inferrer) {
     for (var statement in statements) {
       inferrer.inferStatement(statement);
     }
   }
 }
 
+/// Concrete shadow object representing a boolean literal in kernel form.
+class KernelBoolLiteral extends BoolLiteral implements KernelExpression {
+  KernelBoolLiteral(bool value) : super(value);
+
+  @override
+  DartType _inferExpression(
+      KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
+    return inferrer.inferBoolLiteral(typeContext, typeNeeded);
+  }
+}
+
 /// Concrete shadow object representing a double literal in kernel form.
 class KernelDoubleLiteral extends DoubleLiteral implements KernelExpression {
   KernelDoubleLiteral(double value) : super(value);
 
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
     return inferrer.inferDoubleLiteral(typeContext, typeNeeded);
   }
 }
@@ skipping 170 matching lines @@
 class KernelStaticGet extends StaticGet implements KernelExpression {
   KernelStaticGet(Member target) : super(target);
 
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
     return inferrer.inferStaticGet(typeContext, typeNeeded, target.getterType);
   }
 }
 
+/// Concrete shadow object representing a string concatenation in kernel form.
+class KernelStringConcatenation extends StringConcatenation
+    implements KernelExpression {
+  KernelStringConcatenation(List<Expression> expressions) : super(expressions);
+
+  @override
+  DartType _inferExpression(
+      KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
+    return inferrer.inferStringLiteral(typeContext, typeNeeded);

[Paul Berry, 2017/05/01 22:03:44]

This works for now, but in the long run it will need to recurse into the
subexpressions in order to handle stuff like:

f(x) {
  if (x is int) {
    return "$x"; // (1)
  }
}

(the kernel object for the reference to `x` at (1) needs to have its
promotedType field set to `int`, and that will only happen if we recurse into
the subexpression).

Would you mind adding a TODO comment?

[scheglov, 2017/05/02 02:35:20]

Done.
I ended up removing testing for StringConcatenation at all, because with
analyzer we do report the promoted type, but not in front_end yet.

+  }
+}
+
+/// Concrete shadow object representing a string literal in kernel form.
+class KernelStringLiteral extends StringLiteral implements KernelExpression {
+  KernelStringLiteral(String value) : super(value);
+
+  @override
+  DartType _inferExpression(
+      KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
+    return inferrer.inferStringLiteral(typeContext, typeNeeded);
+  }
+}
+
 /// Concrete implementation of [TypeInferenceEngine] specialized to work with
 /// kernel objects.
 class KernelTypeInferenceEngine extends TypeInferenceEngineImpl<KernelField> {
   KernelTypeInferenceEngine(Instrumentation instrumentation, bool strongMode)
       : super(instrumentation, strongMode);
 
   @override
   void clearFieldInitializer(KernelField field) {
     field.initializer = null;
   }
@@ skipping 248 matching lines @@
       // KernelVariableDeclaration.
       mutatedInClosure = true;
       declaredType = variable.type;
     }
     return inferrer.inferVariableGet(typeContext, typeNeeded, mutatedInClosure,
         _fact, _scope, fileOffset, declaredType, (type) {
       promotedType = type;
     });
   }
 }