[cfe] Handle exhaustiveness checking in expression evaluation

The expression evaluator called directly into the constant evaluator,
skipping the setting up of the exhaustiveness cache used for
exhaustiveness checking.

Closes #52905

Change-Id: I367ff73d8e23127811f99dfbf451e66eef452443
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/314060
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

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

@@ -141,7 +141,7 @@ void transformProcedure(
       typeEnvironment,
       errorReporter,
       evaluationMode);
-  constantsTransformer.visitProcedure(procedure, null);
+  constantsTransformer.convertProcedure(procedure);
 }
 
 enum EvaluationMode {
@@ -443,6 +443,14 @@ class ConstantsTransformer extends RemovingTransformer {
     _exhaustivenessCache = null;
   }
 
+  Procedure convertProcedure(Procedure node) {
+    _exhaustivenessCache =
+        new CfeExhaustivenessCache(constantEvaluator, node.enclosingLibrary);
+    Procedure result = visitProcedure(node, null);
+    _exhaustivenessCache = null;
+    return result;
+  }
+
   @override
   LibraryPart visitLibraryPart(LibraryPart node, TreeNode? removalSentinel) {
     constantEvaluator.withNewEnvironment(() {

pkg/front_end/testcases/expression/issue52905.expression.yaml

@@ -0,0 +1,41 @@
+# Copyright (c) 2023, 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.
+
+sources: |
+  class Color {
+    final String name;
+    Color(this.name);
+  }
+  
+  class Theme {
+    Color get primary => Color('primary');
+    Color get white => Color('white');
+    Color get transparent => Color('transparent');
+  }
+  
+  enum _Type {
+    primary,
+    background,
+    outline,
+    text,
+  }
+  
+  class Class {
+    final _Type _type;
+    final Theme theme;
+    final Color? backgroundColor;
+  
+    Class(this._type, this.theme, this.backgroundColor);
+
+    method() {
+    }
+  }
+definitions: []
+position: "#Class"
+expression: |
+  switch (_type) {
+    _Type.primary => theme.primary,
+    _Type.background => theme.white,
+    _Type.outline || _Type.text => theme.transparent,
+  }

pkg/front_end/testcases/expression/issue52905.expression.yaml.expect

@@ -0,0 +1,43 @@
+Errors: {
+}
+method /* from org-dartlang-debug:synthetic_debug_expression */ debugExpr() → dynamic
+  return block {
+    #lib1::Color #t1;
+    final synthesized #lib1::_Type #0#0 = this.{#lib1::Class::_type}{#lib1::_Type};
+    #L1:
+    {
+      {
+        if(#C3 =={dart.core::Object::==}{(dart.core::Object) → dart.core::bool} #0#0) {
+          #t1 = this.{#lib1::Class::theme}{#lib1::Theme}.{#lib1::Theme::primary}{#lib1::Color};
+          break #L1;
+        }
+      }
+      {
+        if(#C6 =={dart.core::Object::==}{(dart.core::Object) → dart.core::bool} #0#0) {
+          #t1 = this.{#lib1::Class::theme}{#lib1::Theme}.{#lib1::Theme::white}{#lib1::Color};
+          break #L1;
+        }
+      }
+      {
+        if(#C9 =={dart.core::Object::==}{(dart.core::Object) → dart.core::bool} #0#0 || #C12 =={dart.core::Object::==}{(dart.core::Object) → dart.core::bool} #0#0) {
+          #t1 = this.{#lib1::Class::theme}{#lib1::Theme}.{#lib1::Theme::transparent}{#lib1::Color};
+          break #L1;
+        }
+      }
+      throw new dart._internal::ReachabilityError::•("`null` encountered as case in a switch expression with a non-nullable type.");
+    }
+  } =>#t1;
+constants  {
+  #C1 = 0
+  #C2 = "primary"
+  #C3 = #lib1::_Type {index:#C1, _name:#C2}
+  #C4 = 1
+  #C5 = "background"
+  #C6 = #lib1::_Type {index:#C4, _name:#C5}
+  #C7 = 2
+  #C8 = "outline"
+  #C9 = #lib1::_Type {index:#C7, _name:#C8}
+  #C10 = 3
+  #C11 = "text"
+  #C12 = #lib1::_Type {index:#C10, _name:#C11}
+}