New J2K: Do not remove semicolon after if expression when then branch is empty in RedundantSemicolonInspection

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

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.*
+import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 class RedundantSemicolonInspection : AbstractKotlinInspection(), CleanupLocalInspectionTool {
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession): PsiElementVisitor {
@@ -79,6 +80,11 @@ class RedundantSemicolonInspection : AbstractKotlinInspection(), CleanupLocalIns
                 return false
         }
 
+        semicolon.prevLeaf()?.parent?.safeAs<KtIfExpression>()?.also { ifExpression ->
+            if (ifExpression.then == null)
+                return false
+        }
+
         if (nextLeaf?.nextLeaf {
                 it !is PsiWhiteSpace && it !is PsiComment && it.getStrictParentOfType<KDoc>() == null &&
                         it.getStrictParentOfType<KtAnnotationEntry>() == null

idea/testData/inspections/redundantSemicolon/Test.kt

@@ -34,6 +34,7 @@ fun bar() {
 fun baz(args: Array<String>) {
     for (arg in args);
     while (args.size > 0);
+    if (args.size > 0);
     // But here redundant!
     do while (args.size > 0);
 }

idea/testData/inspections/redundantSemicolon/inspectionData/expected.xml

@@ -72,16 +72,7 @@
     </problem>
     <problem>
         <file>Test.kt</file>
-        <line>38</line>
+        <line>39</line>
-        <module>light_idea_test_case</module>
-        <entry_point TYPE="file" FQNAME="temp:///src/Test.kt" />
-        <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant semicolon</problem_class>
-        <description>Redundant semicolon</description>
-    </problem>
-
-    <problem>
-        <file>Test.kt</file>
-        <line>43</line>
         <module>light_idea_test_case</module>
         <entry_point TYPE="file" FQNAME="temp:///src/Test.kt" />
         <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant semicolon</problem_class>
@@ -108,7 +99,16 @@
 
     <problem>
         <file>Test.kt</file>
-        <line>49</line>
+        <line>46</line>
+        <module>light_idea_test_case</module>
+        <entry_point TYPE="file" FQNAME="temp:///src/Test.kt" />
+        <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant semicolon</problem_class>
+        <description>Redundant semicolon</description>
+    </problem>
+
+    <problem>
+        <file>Test.kt</file>
+        <line>50</line>
         <module>light_idea_test_case</module>
         <entry_point TYPE="file" FQNAME="temp:///src/Test.kt" />
         <problem_class severity="WARNING" attribute_key="NOT_USED_ELEMENT_ATTRIBUTES">Redundant semicolon</problem_class>