Issue sevntu-checkstyle#882: update LogicConditionNeedOptimizationChe…

…ck to avoid false positive

sevntu-checks/src/main/java/com/github/sevntu/checkstyle/checks/coding/LogicConditionNeedOptimizationCheck.java

@@ -88,7 +88,7 @@ private static boolean needOptimization(DetailAST logicNode) {
         final boolean secondTypeCast = branchContains(operands, 2, TokenTypes.TYPECAST);
         final boolean result;
 
-        if (firstInstanceOf && secondTypeCast) {
+        if (isPatternVariableIntroduced(logicNode) || firstInstanceOf && secondTypeCast) {
             result = false;
         }
         else {
@@ -190,4 +190,18 @@ private static boolean branchContains(DetailAST start, DetailAST end, int type)
         return result;
     }
 
+    /**
+     *  If pattern variable is introduced, 'instanceof` must appear before condition
+     *  that checks pattern variable.
+     *
+     * @param logicNode logic node whose children we check
+     * @return true if a pattern variable is introduced
+     */
+    private static boolean isPatternVariableIntroduced(DetailAST logicNode) {
+        final DetailAST firstOperand = logicNode.getFirstChild();
+        return firstOperand.getType() == TokenTypes.LITERAL_INSTANCEOF
+                        && firstOperand.getLastChild() != null
+                        && firstOperand.getLastChild().getType() == TokenTypes.PATTERN_VARIABLE_DEF;
+    }
+
 }

sevntu-checks/src/test/java/com/github/sevntu/checkstyle/checks/coding/LogicConditionNeedOptimizationCheckTest.java

@@ -25,6 +25,7 @@
 
 import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
 import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
+import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
 
 public class LogicConditionNeedOptimizationCheckTest extends AbstractModuleTestSupport {
 
@@ -66,4 +67,14 @@ public void test() throws Exception {
         verify(checkConfig, getPath("InputLogicConditionNeedOptimizationCheck.java"), expected);
     }
 
+    @Test
+    public void testJava17Patterns() throws Exception {
+        final DefaultConfiguration checkConfig =
+                createModuleConfig(LogicConditionNeedOptimizationCheck.class);
+        final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
+        verify(checkConfig,
+                getNonCompilablePath("InputLogicConditionNeedsOptimizationPatterns.java"),
+                expected);
+    }
+
 }

sevntu-checks/src/test/resources-noncompilable/com/github/sevntu/checkstyle/checks/coding/InputLogicConditionNeedsOptimizationPatterns.java

@@ -0,0 +1,16 @@
+package com.github.sevntu.checkstyle.checks.coding;
+
+public class InputLogicConditionNeedsOptimizationPatterns {
+    void m1(Object o) {
+        for (int i = 0; o instanceof Integer myInt && myInt > 5;) { // ok
+            // type pattern, no `PATTERN_DEF`
+        }
+        for (int i = 0; o instanceof (Integer myInt && myInt > 5);) { // ok
+            // parenthesized pattern, `PATTERN_DEF`
+        }
+        for (int i = 0; o instanceof Integer myInt; ) { // ok
+            // type pattern, no `PATTERN_DEF`
+        }
+    }
+
+}