Use "bool" as the downward inference context for assert conditions.

This addresses the type inference part of #30326.

R=scheglov@google.com

Review-Url: https://codereview.chromium.org/2997513002 .

pkg/analyzer/lib/src/generated/resolver.dart

@@ -5195,8 +5195,16 @@ class ResolverVisitor extends ScopedVisitor {
     return null;
   }
 
+  @override
+  Object visitAssertInitializer(AssertInitializer node) {
+    InferenceContext.setType(node.condition, typeProvider.boolType);
+    super.visitAssertInitializer(node);
+    return null;
+  }
+
   @override
   Object visitAssertStatement(AssertStatement node) {
+    InferenceContext.setType(node.condition, typeProvider.boolType);
     super.visitAssertStatement(node);
     _propagateTrueState(node.condition);
     return null;

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

@@ -119,7 +119,8 @@ class KernelAssertStatement extends AssertStatement implements KernelStatement {
   @override
   void _inferStatement(KernelTypeInferrer inferrer) {
     inferrer.listener.assertStatementEnter(this);
-    inferrer.inferExpression(condition, null, false);
+    inferrer.inferExpression(
+        condition, inferrer.coreTypes.boolClass.rawType, false);
     if (message != null) {
       inferrer.inferExpression(message, null, false);
     }

pkg/front_end/testcases/inference/assert.dart

@@ -8,8 +8,8 @@ library test;
 T f<T>() => null;
 
 void test() {
-  assert(/*@typeArgs=dynamic*/ f());
-  assert(/*@typeArgs=dynamic*/ f(), /*@typeArgs=dynamic*/ f());
+  assert(/*@typeArgs=bool*/ f());
+  assert(/*@typeArgs=bool*/ f(), /*@typeArgs=dynamic*/ f());
 }
 
 main() {}

pkg/front_end/testcases/inference/assert.dart.strong.expect

@@ -5,7 +5,7 @@ import "dart:core" as core;
 static method f<T extends core::Object>() → self::f::T
   return null;
 static method test() → void {
-  assert(self::f<dynamic>());
-  assert(self::f<dynamic>(), self::f<dynamic>());
+  assert(self::f<core::bool>());
+  assert(self::f<core::bool>(), self::f<dynamic>());
 }
 static method main() → dynamic {}

pkg/front_end/testcases/inference/assert_initializer.dart

@@ -8,14 +8,14 @@ library test;
 T f<T>() => null;
 
 class C {
-  C.expressionOnly() : assert(/*@typeArgs=dynamic*/ f());
+  C.expressionOnly() : assert(/*@typeArgs=bool*/ f());
   C.expressionAndMessage()
-      : assert(/*@typeArgs=dynamic*/ f(), /*@typeArgs=dynamic*/ f());
+      : assert(/*@typeArgs=bool*/ f(), /*@typeArgs=dynamic*/ f());
 }
 
 main() {
   // Test type inference of assert statements just to verify that the behavior
   // is the same.
-  assert(/*@typeArgs=dynamic*/ f());
-  assert(/*@typeArgs=dynamic*/ f(), /*@typeArgs=dynamic*/ f());
+  assert(/*@typeArgs=bool*/ f());
+  assert(/*@typeArgs=bool*/ f(), /*@typeArgs=dynamic*/ f());
 }

pkg/front_end/testcases/inference/assert_initializer.dart.strong.expect

@@ -5,18 +5,18 @@ import "dart:core" as core;
 class C extends core::Object {
   constructor expressionOnly() → void
     : final dynamic #t1 = () → dynamic
-      assert(self::f<dynamic>());
+      assert(self::f<core::bool>());
 .call(), super core::Object::•()
     ;
   constructor expressionAndMessage() → void
     : final dynamic #t2 = () → dynamic
-      assert(self::f<dynamic>(), self::f<dynamic>());
+      assert(self::f<core::bool>(), self::f<dynamic>());
 .call(), super core::Object::•()
     ;
 }
 static method f<T extends core::Object>() → self::f::T
   return null;
 static method main() → dynamic {
-  assert(self::f<dynamic>());
-  assert(self::f<dynamic>(), self::f<dynamic>());
+  assert(self::f<core::bool>());
+  assert(self::f<core::bool>(), self::f<dynamic>());
 }