Introduce "Add '== true'" quick fix for TYPE_MISMATCH

#KT-39930 Fixed

idea/resources-en/messages/KotlinBundle.properties

@@ -2240,6 +2240,7 @@ title.import.layout=Import Layout
 title.packages.to.use.import.with=Packages to Use Import with '*'
 redundant.qualifier.unnecessary.non.direct.parent.class.qualifier=Unnecessary non-direct parent classes qualifiers
 fix.add.exception.to.throws=Add ''{0}''
+fix.add.eq.eq.true=Add '== true'
 
 hints.title.codevision=Code Vision
 hints.title.codevision.show.hints.for=Show hints for:

idea/src/org/jetbrains/kotlin/idea/quickfix/AddEqEqTrueFix.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2020 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.idea.quickfix
+
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import org.jetbrains.kotlin.idea.KotlinBundle
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.psi.createExpressionByPattern
+
+class AddEqEqTrueFix(expression: KtExpression) : KotlinQuickFixAction<KtExpression>(expression) {
+    override fun getText() = KotlinBundle.message("fix.add.eq.eq.true")
+
+    override fun getFamilyName() = text
+
+    override fun invoke(project: Project, editor: Editor?, file: KtFile) {
+        val expression = element ?: return
+        expression.replace(KtPsiFactory(expression).createExpressionByPattern("$0 == true", expression))
+    }
+}

idea/src/org/jetbrains/kotlin/idea/quickfix/QuickFixFactoryForTypeMismatchError.kt

@@ -50,10 +50,7 @@ import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.types.KotlinType
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.types.TypeUtils.NO_EXPECTED_TYPE
-import org.jetbrains.kotlin.types.typeUtil.isInterface
-import org.jetbrains.kotlin.types.typeUtil.isSignedOrUnsignedNumberType
-import org.jetbrains.kotlin.types.typeUtil.isSubtypeOf
-import org.jetbrains.kotlin.types.typeUtil.makeNullable
+import org.jetbrains.kotlin.types.typeUtil.*
 import java.util.*
 
 //TODO: should use change signature to deal with cases of multiple overridden descriptors
@@ -168,7 +165,11 @@ class QuickFixFactoryForTypeMismatchError : KotlinIntentionActionsFactory() {
         if (!expectedType.isMarkedNullable && TypeUtils.isNullableType(expressionType)) {
             val nullableExpected = expectedType.makeNullable()
             if (expressionType.isSubtypeOf(nullableExpected)) {
-                actions.add(AddExclExclCallFix(diagnosticElement.getTopMostQualifiedForSelectorIfAny()))
+                val targetExpression = diagnosticElement.getTopMostQualifiedForSelectorIfAny()
+                actions.add(AddExclExclCallFix(targetExpression))
+                if (expectedType.isBoolean()) {
+                    actions.add(AddEqEqTrueFix(targetExpression))
+                }
             }
         }
 

idea/testData/quickfix/addEqEqTrue/notBoolean.kt

@@ -0,0 +1,10 @@
+// "Add '== true'" "false"
+// DISABLE-ERRORS
+class Foo {
+    fun bar() = ""
+}
+
+fun test(foo: Foo?) {
+    if (foo?.bar()<caret>) {
+    }
+}

idea/testData/quickfix/addEqEqTrue/notBoolean2.kt

@@ -0,0 +1,14 @@
+// "Add '== true'" "false"
+// DISABLE-ERRORS
+// ACTION: Add 'toString()' call
+// ACTION: Change parameter 's' type of function 'baz' to 'Boolean?'
+// ACTION: Create function 'baz'
+class Foo {
+    fun bar() = true
+}
+
+fun baz(s: String) {}
+
+fun test(foo: Foo?) {
+    baz(foo?.bar()<caret>)
+}

idea/testData/quickfix/addEqEqTrue/simple.kt

@@ -0,0 +1,9 @@
+// "Add '== true'" "true"
+class Foo {
+    fun bar() = true
+}
+
+fun test(foo: Foo?) {
+    if (foo?.bar()<caret>) {
+    }
+}

idea/testData/quickfix/addEqEqTrue/simple.kt.after

@@ -0,0 +1,9 @@
+// "Add '== true'" "true"
+class Foo {
+    fun bar() = true
+}
+
+fun test(foo: Foo?) {
+    if (foo?.bar() == true) {
+    }
+}

idea/testData/quickfix/addEqEqTrue/simple2.kt

@@ -0,0 +1,10 @@
+// "Add '== true'" "true"
+class Foo {
+    fun bar() = true
+}
+
+fun baz(b: Boolean) {}
+
+fun test(foo: Foo?) {
+    baz(foo?.bar()<caret>)
+}

idea/testData/quickfix/addEqEqTrue/simple2.kt.after

@@ -0,0 +1,10 @@
+// "Add '== true'" "true"
+class Foo {
+    fun bar() = true
+}
+
+fun baz(b: Boolean) {}
+
+fun test(foo: Foo?) {
+    baz(foo?.bar() == true)
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixMultiFileTestGenerated.java

@@ -111,6 +111,19 @@ public class QuickFixMultiFileTestGenerated extends AbstractQuickFixMultiFileTes
         }
     }
 
+    @TestMetadata("idea/testData/quickfix/addEqEqTrue")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class AddEqEqTrue extends AbstractQuickFixMultiFileTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTestWithExtraFile, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInAddEqEqTrue() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/quickfix/addEqEqTrue"), Pattern.compile("^(\\w+)\\.((before\\.Main\\.\\w+)|(test))$"), null, true);
+        }
+    }
+
     @TestMetadata("idea/testData/quickfix/addExclExclCall")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -576,6 +576,39 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
         }
     }
 
+    @TestMetadata("idea/testData/quickfix/addEqEqTrue")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class AddEqEqTrue extends AbstractQuickFixTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInAddEqEqTrue() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/quickfix/addEqEqTrue"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("notBoolean.kt")
+        public void testNotBoolean() throws Exception {
+            runTest("idea/testData/quickfix/addEqEqTrue/notBoolean.kt");
+        }
+
+        @TestMetadata("notBoolean2.kt")
+        public void testNotBoolean2() throws Exception {
+            runTest("idea/testData/quickfix/addEqEqTrue/notBoolean2.kt");
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("idea/testData/quickfix/addEqEqTrue/simple.kt");
+        }
+
+        @TestMetadata("simple2.kt")
+        public void testSimple2() throws Exception {
+            runTest("idea/testData/quickfix/addEqEqTrue/simple2.kt");
+        }
+    }
+
     @TestMetadata("idea/testData/quickfix/addExclExclCall")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)