IDEA-184733 Better array access tracking in DFA

java/java-tests/testData/codeInsight/completion/normal/CastInstanceofedThisQualifier.java

@@ -9,7 +9,7 @@ public abstract class Super {
 
 }
 
-class Sub extends Zzza {
+interface Sub extends Zzza {
   void subMethod() {}
 
 }

java/java-tests/testData/codeInsight/completion/normal/CastInstanceofedThisQualifier_after.java

@@ -9,7 +9,7 @@ public abstract class Super {
 
 }
 
-class Sub extends Zzza {
+interface Sub extends Zzza {
   void subMethod() {}
 
 }

java/java-tests/testData/inspection/dataFlow/fixture/AdvancedArrayAccess.java

@@ -0,0 +1,108 @@
+import java.util.*;
+
+class AdvancedArrayAccess {
+  private static final int[] LENGTH = {0, 10, 20, 30};
+  private static final int[] LENGTH2 = {0, 10, 20, 30};
+
+  void testInstanceOf() {
+    Object[] arr = {new String("foo"), new Integer(0)};
+    if(<warning descr="Condition 'arr[0] instanceof Number' is always 'false'">arr[0] instanceof Number</warning>) {
+      System.out.println(((Number)arr[0]).intValue());
+    }
+  }
+
+  void testStaticFinal() {
+    if(<warning descr="Condition 'LENGTH[2] == 20' is always 'true'">LENGTH[2] == 20</warning>) {
+      System.out.println("ok");
+    }
+  }
+
+  int[] getLengths() {
+    // array is still read-only
+    return LENGTH.clone();
+  }
+
+  int getLengthsCount() {
+    // array is still read-only
+    return LENGTH.length;
+  }
+
+  int[] getLength2() {
+    // Reference leaks: do not consider an array as read-only
+    return LENGTH2;
+  }
+
+  void testStaticFinal(int idx) {
+    if(idx == 2 && <warning descr="Condition 'LENGTH[idx] == 20' is always 'true' when reached">LENGTH[idx] == 20</warning>) {
+      System.out.println("ok");
+    }
+  }
+
+  void testStaticFinalRW(int idx) {
+    if(idx == 2 && LENGTH2[idx] == 20) {
+      System.out.println("ok");
+    }
+  }
+
+  void testWrite(int[] arr, int idx) {
+    if(idx != 0) return;
+    arr[idx] = 10;
+    if(<warning descr="Condition 'arr[0] == 11' is always 'false'">arr[0] == 11</warning>) {
+      System.out.println("impossible");
+    }
+  }
+
+  void testSplitState(boolean b, String[] data) {
+    data[1] = "A";
+    data[2] = "B";
+    int idx = b ? 0 : 1;
+    data[idx] = "C";
+    if(<warning descr="Condition 'data[2].equals(\"D\")' is always 'false'">data[2].equals("D")</warning>) {
+      System.out.println("never");
+    }
+    if(<warning descr="Condition 'data[1].equals(\"E\")' is always 'false'">data[1].equals("E")</warning>) {
+      System.out.println("never");
+    }
+    if(data[1].equals("A") && <warning descr="Condition 'b' is always 'true' when reached">b</warning>) {
+      System.out.println("Only if b is true");
+    }
+  }
+
+  // Should not be too complex
+  static int max(float[] array) {
+    int max = 0;
+    float val = array[0];
+    for (int i = 1; i < array.length; i++) {
+      if (val < array[i]) {
+        max = i;
+        val = array[i];
+      }
+    }
+    return max;
+  }
+
+  void processArray(String[] arr) {
+    for(int i=0; i<arr.length; i++) {
+      if(arr[i].isEmpty()) arr[i] = null; // No NPE warning here even if we update arr[i] to null we'll never visit same element twice
+    }
+  }
+
+  void testMethodQualifier() {
+    if(getData()[0] == null) {
+      System.out.println(getData()[0].<warning descr="Method invocation 'trim' may produce 'java.lang.NullPointerException'">trim</warning>());
+    }
+  }
+
+  final String[] getData() {
+    return new String[] {"a", "b", "c"};
+  }
+
+  void testConditional(String[] arr, int idx) {
+    if(idx == 0) {
+      arr[idx] = "foo";
+    }
+    if(<warning descr="Condition 'arr[0].equals(\"bar\") && idx == 0' is always 'false'">arr[0].equals("bar") && <warning descr="Condition 'idx == 0' is always 'false' when reached">idx == 0</warning></warning>) {
+      System.out.println("never");
+    }
+  }
+}

java/java-tests/testData/inspection/dataFlow/fixture/ArrayLength.java

@@ -68,4 +68,14 @@ public final class ArrayLength {
     Arrays.fill(x, -1);
     Arrays.<warning descr="The call to 'fill' always fails as index is out of bounds">fill</warning>(x, -1, -1, -1);
   }
+
+  static final String[] ARR1 = {};
+  static final String[] ARR2 = new String[10];
+  static final String[] ARR3 = new String[] {"foo", "bar", "baz"};
+
+  void testFieldInitializers() {
+    if(<warning descr="Condition 'ARR1.length == 0' is always 'true'">ARR1.length == 0</warning>) System.out.println("yes");
+    if(<warning descr="Condition 'ARR2.length == 10' is always 'true'">ARR2.length == 10</warning>) System.out.println("yes");
+    if(<warning descr="Condition 'ARR3.length == 3' is always 'true'">ARR3.length == 3</warning>) System.out.println("yes");
+  }
 }

java/java-tests/testData/inspection/dataFlow/fixture/LongRangeBasics.java

@@ -99,6 +99,11 @@ public class LongRangeBasics {
     }
   }
 
+  static final String FOO = "bar";
+
+  void testStaticLength() {
+    if(<warning descr="Condition 'FOO.isEmpty()' is always 'false'">FOO.isEmpty()</warning>) System.out.println("nope");
+  }
 
   void testWrongMerge(boolean a, boolean b, int c) {
     int currentLevel = 0;