Fix parsing regression related to T!!

^KT-47445 Fixed

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -196,6 +196,8 @@ public interface Errors {
     DiagnosticFactory1<KtElement, KotlinType> EXPANDED_TYPE_CANNOT_BE_CONSTRUCTED = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<KtTypeElement, KotlinType> EXPANDED_TYPE_CANNOT_BE_INHERITED = DiagnosticFactory1.create(ERROR);
 
+    DiagnosticFactory0<KtPostfixExpression> DEPRECATED_SYNTAX_WITH_DEFINITELY_NOT_NULL = DiagnosticFactory0.create(WARNING);
+
     DiagnosticFactory0<KtModifierList> MODIFIER_LIST_NOT_ALLOWED = DiagnosticFactory0.create(ERROR);
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -601,6 +601,7 @@ public class DefaultErrorMessages {
         MAP.put(UNUSED_TYPEALIAS_PARAMETER, "Type alias parameter {0} is not used in the expanded type {1} and does not affect type checking", NAME, RENDER_TYPE);
         MAP.put(EXPANDED_TYPE_CANNOT_BE_CONSTRUCTED, "Expanded type {0} contains non-invariant projections in top-level arguments and cannot be constructed", RENDER_TYPE);
         MAP.put(EXPANDED_TYPE_CANNOT_BE_INHERITED, "Expanded type {0} contains non-invariant projections in top-level arguments and cannot be inherited from", RENDER_TYPE);
+        MAP.put(DEPRECATED_SYNTAX_WITH_DEFINITELY_NOT_NULL, "Applying ''!!'' to the whole as/is expression without parentheses is deprecated. Please, put parentheses explicitly");
 
         MAP.put(MODIFIER_LIST_NOT_ALLOWED, "Modifiers and annotations are not allowed here, because there are other modifiers or annotations outside of parenthesis");
 

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java

@@ -293,6 +293,8 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
             return facade.getTypeInfo(left, contextWithNoExpectedType).clearType();
         }
 
+        DefinitelyNotNullDeprecationKt.reportDeprecatedDefinitelyNotNullSyntax(expression, right, context);
+
         IElementType operationType = expression.getOperationReference().getReferencedNameElementType();
 
         boolean allowBareTypes = BARE_TYPES_ALLOWED.contains(operationType);

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PatternMatchingTypingVisitor.kt

@@ -60,6 +60,8 @@ class PatternMatchingTypingVisitor internal constructor(facade: ExpressionTyping
             context.trace.record(BindingContext.DATAFLOW_INFO_AFTER_CONDITION, expression, newDataFlowInfo)
         }
 
+        expression.reportDeprecatedDefinitelyNotNullSyntax(expression.typeReference, contextWithExpectedType)
+
         val resultTypeInfo = components.dataFlowAnalyzer.checkType(
             typeInfo.replaceType(components.builtIns.booleanType),
             expression,

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/definitelyNotNullDeprecation.kt

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.types.expressions
+
+import com.intellij.psi.impl.source.tree.LeafPsiElement
+import com.intellij.psi.util.PsiTreeUtil
+import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtOperationExpression
+import org.jetbrains.kotlin.psi.KtPostfixExpression
+import org.jetbrains.kotlin.psi.KtTypeReference
+import org.jetbrains.kotlin.psi.KtUserType
+import org.jetbrains.kotlin.psi.psiUtil.nextLeaf
+
+fun KtOperationExpression.reportDeprecatedDefinitelyNotNullSyntax(
+    rhs: KtTypeReference?,
+    context: ExpressionTypingContext
+) {
+    val nextLeaf = nextLeaf()
+    if (nextLeaf is LeafPsiElement && nextLeaf.elementType === KtTokens.EXCLEXCL && rhs?.typeElement is KtUserType) {
+        val parent = PsiTreeUtil.findCommonParent(nextLeaf, this)
+        if (parent is KtPostfixExpression && parent.operationToken === KtTokens.EXCLEXCL) {
+            context.trace.report(Errors.DEPRECATED_SYNTAX_WITH_DEFINITELY_NOT_NULL.on((parent as KtPostfixExpression?)!!))
+        }
+    }
+}