RemoveCurlyBracesFromTemplateInspection: add heuristic to change severity

Change severity to INFORMATION if a variable hasn't whitespace around & add an option to return the old behavior
 #KT-31717 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/RemoveCurlyBracesFromTemplateInspection.kt

@@ -5,16 +5,23 @@
 
 package org.jetbrains.kotlin.idea.inspections
 
+import com.intellij.codeInspection.ProblemHighlightType
+import com.intellij.codeInspection.ui.MultipleCheckboxOptionsPanel
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.idea.core.canDropBraces
 import org.jetbrains.kotlin.idea.core.dropBraces
 import org.jetbrains.kotlin.psi.KtBlockStringTemplateEntry
 
-class RemoveCurlyBracesFromTemplateInspection :
+class RemoveCurlyBracesFromTemplateInspection(@JvmField var reportWithoutWhitespace: Boolean = false) :
     AbstractApplicabilityBasedInspection<KtBlockStringTemplateEntry>(KtBlockStringTemplateEntry::class.java) {
     override fun inspectionText(element: KtBlockStringTemplateEntry): String = "Redundant curly braces in string template"
 
+    override fun inspectionHighlightType(element: KtBlockStringTemplateEntry) =
+        if (reportWithoutWhitespace || element.hasWhitespaceAround()) ProblemHighlightType.GENERIC_ERROR_OR_WARNING
+        else ProblemHighlightType.INFORMATION
+
     override val defaultFixText: String = "Remove curly braces"
 
     override fun isApplicable(element: KtBlockStringTemplateEntry): Boolean = element.canDropBraces()
@@ -22,4 +29,16 @@ class RemoveCurlyBracesFromTemplateInspection :
     override fun applyTo(element: KtBlockStringTemplateEntry, project: Project, editor: Editor?) {
         element.dropBraces()
     }
+
+    override fun createOptionsPanel() = MultipleCheckboxOptionsPanel(this).apply {
+        addCheckbox("Report also for a variables without a whitespace around", "reportWithoutWhitespace")
+    }
 }
+
+private fun KtBlockStringTemplateEntry.hasWhitespaceAround(): Boolean =
+    prevSibling?.isWhitespaceOrQuote(true) == true && nextSibling?.isWhitespaceOrQuote(false) == true
+
+private fun PsiElement.isWhitespaceOrQuote(prev: Boolean): Boolean {
+    val char = if (prev) text.lastOrNull() else text.firstOrNull()
+    return char != null && (char.isWhitespace() || char == '"')
+}

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets1.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets1.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets2.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets2.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets3.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets3.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets4.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets4.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets5.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets5.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets6.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets6.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: INFORMATION
 
 fun foo() {
     val x = 4

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets7.kt

@@ -1,3 +1,4 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
 
 fun foo(`object`: Any) {
     val bar = "$<caret>{`object`}"

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets7.kt.after

@@ -1,3 +1,4 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
 
 fun foo(`object`: Any) {
     val bar = "$`object`"

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets8.kt

@@ -0,0 +1,6 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
+fun foo() {
+    val x = 4
+    val y = "text $<caret>{x} moretext"
+}

idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets8.kt.after

@@ -0,0 +1,6 @@
+// HIGHLIGHT: GENERIC_ERROR_OR_WARNING
+
+fun foo() {
+    val x = 4
+    val y = "text $x moretext"
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -7884,6 +7884,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
         public void testUnnecessaryBrackets7() throws Exception {
             runTest("idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets7.kt");
         }
+
+        @TestMetadata("unnecessaryBrackets8.kt")
+        public void testUnnecessaryBrackets8() throws Exception {
+            runTest("idea/testData/inspectionsLocal/removeCurlyBracesFromTemplate/unnecessaryBrackets8.kt");
+        }
     }
 
     @TestMetadata("idea/testData/inspectionsLocal/removeEmptyParenthesesFromAnnotationEntry")