Merge pull request #19883 from aschackmull/java/fix-assert-cfg

Java: Fix assert CFG by properly tagging the false successor.

Author: aschackmull

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -100,7 +100,8 @@ module ControlFlow {
   private newtype TNode =
     TExprNode(Expr e) { hasControlFlow(e) } or
     TStmtNode(Stmt s) or
-    TExitNode(Callable c) { exists(c.getBody()) }
+    TExitNode(Callable c) { exists(c.getBody()) } or
+    TAssertThrowNode(AssertStmt s)
 
   /** A node in the expression-level control-flow graph. */
   class Node extends TNode {
@@ -204,6 +205,25 @@ module ControlFlow {
     /** Gets the source location for this element. */
     override Location getLocation() { result = c.getLocation() }
   }
+
+  /** A control flow node indicating a failing assertion. */
+  class AssertThrowNode extends Node, TAssertThrowNode {
+    AssertStmt s;
+
+    AssertThrowNode() { this = TAssertThrowNode(s) }
+
+    override Stmt getEnclosingStmt() { result = s }
+
+    override Callable getEnclosingCallable() { result = s.getEnclosingCallable() }
+
+    override ExprParent getAstNode() { result = s }
+
+    /** Gets a textual representation of this element. */
+    override string toString() { result = "Assert Throw" }
+
+    /** Gets the source location for this element. */
+    override Location getLocation() { result = s.getLocation() }
+  }
 }
 
 class ControlFlowNode = ControlFlow::Node;
@@ -327,7 +347,17 @@ private module ControlFlowGraphImpl {
     )
   }
 
-  private ThrowableType assertionError() { result.hasQualifiedName("java.lang", "AssertionError") }
+  private ThrowableType actualAssertionError() {
+    result.hasQualifiedName("java.lang", "AssertionError")
+  }
+
+  private ThrowableType assertionError() {
+    result = actualAssertionError()
+    or
+    // In case `AssertionError` is not extracted, we use `Error` as a fallback.
+    not exists(actualAssertionError()) and
+    result.hasQualifiedName("java.lang", "Error")
+  }
 
   /**
    * Gets an exception type that may be thrown during execution of the
@@ -1123,12 +1153,7 @@ private module ControlFlowGraphImpl {
       or
       // `assert` statements may throw
       completion = ThrowCompletion(assertionError()) and
-      (
-        last(assertstmt.getMessage(), last, NormalCompletion())
-        or
-        not exists(assertstmt.getMessage()) and
-        last(assertstmt.getExpr(), last, BooleanCompletion(false, _))
-      )
+      last.(AssertThrowNode).getAstNode() = assertstmt
     )
     or
     // `throw` statements or throwing calls give rise to `Throw` completion
@@ -1547,7 +1572,15 @@ private module ControlFlowGraphImpl {
       or
       last(assertstmt.getExpr(), n, completion) and
       completion = BooleanCompletion(false, _) and
-      result = first(assertstmt.getMessage())
+      (
+        result = first(assertstmt.getMessage())
+        or
+        not exists(assertstmt.getMessage()) and
+        result.(AssertThrowNode).getAstNode() = assertstmt
+      )
+      or
+      last(assertstmt.getMessage(), n, NormalCompletion()) and
+      result.(AssertThrowNode).getAstNode() = assertstmt
     )
     or
     // When expressions:

java/ql/test/query-tests/Nullness/C.java

@@ -251,7 +251,7 @@ public void ex18(boolean b, int[] xs, Object related) {
            (b && xs == null && related == null);
     if (b) {
       if (related == null) { return; }
-      xs[0] = 42; // FP - correlated conditions fails to recognize assert edges
+      xs[0] = 42; // OK
     }
   }
 }

java/ql/test/query-tests/Nullness/NullMaybe.expected

@@ -32,9 +32,6 @@
 | C.java:207:9:207:11 | obj | Variable $@ may be null at this access because of $@ assignment. | C.java:201:5:201:22 | Object obj | obj | C.java:201:12:201:21 | obj | this |
 | C.java:219:9:219:10 | o1 | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:212:20:212:28 | o1 | o1 | C.java:213:9:213:18 | ... == ... | this |
 | C.java:233:7:233:8 | xs | Variable $@ may be null at this access because of $@ assignment. | C.java:231:5:231:56 | int[] xs | xs | C.java:231:11:231:55 | xs | this |
-| C.java:254:7:254:8 | xs | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:248:31:248:38 | xs | xs | C.java:249:19:249:28 | ... == ... | this |
-| C.java:254:7:254:8 | xs | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:248:31:248:38 | xs | xs | C.java:250:18:250:27 | ... != ... | this |
-| C.java:254:7:254:8 | xs | Variable $@ may be null at this access as suggested by $@ null guard. | C.java:248:31:248:38 | xs | xs | C.java:251:18:251:27 | ... == ... | this |
 | F.java:11:5:11:7 | obj | Variable $@ may be null at this access as suggested by $@ null guard. | F.java:8:18:8:27 | obj | obj | F.java:9:9:9:19 | ... == ... | this |
 | F.java:17:5:17:7 | obj | Variable $@ may be null at this access as suggested by $@ null guard. | F.java:14:18:14:27 | obj | obj | F.java:15:9:15:19 | ... == ... | this |
 | G.java:20:12:20:12 | s | Variable $@ may be null at this access as suggested by $@ null guard. | G.java:3:27:3:34 | s | s | G.java:5:9:5:17 | ... == ... | this |

java/ql/test/query-tests/RangeAnalysis/A.java

@@ -64,7 +64,7 @@ void m4(int[] a, int[] b) {
     int sum = 0;
     for (int i = 0; i < a.length; ) {
       sum += a[i++]; // OK
-      sum += a[i++]; // OK - FP
+      sum += a[i++]; // OK
     }
     int len = b.length;
     if ((len & 1) != 0)

java/ql/test/query-tests/RangeAnalysis/ArrayIndexOutOfBounds.expected

@@ -3,7 +3,6 @@
 | A.java:45:14:45:22 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |
 | A.java:49:14:49:22 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |
 | A.java:58:14:58:19 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |
-| A.java:67:14:67:19 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |
 | A.java:89:12:89:16 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |
 | A.java:100:18:100:31 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length + 8. |
 | A.java:113:14:113:21 | ...[...] | This array access might be out of bounds, as the index might be equal to the array length. |