Idempotent loop body inspection

Fixes IDEA-180227 Better infinite loop detection

java/java-tests/testData/inspection/idempotentLoopBody/IdempotentLoopBody.java

@@ -0,0 +1,57 @@
+import java.util.*;
+
+class IdempotentLoopBody {
+  String getUniqueName(String baseName, Set<String> names) {
+    int index = 1;
+    String name = baseName;
+    <warning descr="Idempotent loop body">while</warning>(names.contains(name)) {
+      name = baseName + index;
+    }
+    return name;
+  }
+
+  String getUniqueNameComplex(String baseName, Set<String> names) {
+    int index = 1;
+    String name = baseName;
+    <warning descr="Idempotent loop body">while</warning> (names.contains(name)) {
+      String suffix = String.valueOf(index);
+      if (suffix.length() == 1) {
+        suffix = "0" + suffix;
+      }
+      name = baseName + suffix;
+    }
+    return name;
+  }
+
+  String getUniqueNameCorrect(String baseName, Set<String> names) {
+    int index = 1;
+    String name = baseName;
+    while(names.contains(name)) {
+      name = baseName + (index++);
+    }
+    return name;
+  }
+
+  String getUniqueNameFor(String baseName, Set<String> names) {
+    int index = 1;
+    String name;
+    <warning descr="Idempotent loop body">for</warning>(name = baseName; names.contains(name); name = baseName + index);
+    return name;
+  }
+
+  String leftPad(String val, int desiredLength) {
+    String result = val;
+    <warning descr="Idempotent loop body">while</warning>(result.length() < desiredLength) {
+      result = " " + val;
+    }
+    return result;
+  }
+
+  String leftPadCorrect(String val, int desiredLength) {
+    String result = val;
+    while(result.length() < desiredLength) {
+      result = " " + result;
+    }
+    return result;
+  }
+}