[analyzer] trackNullOrUndefValue: always track through parentheses an…

…d casts.

When trying to figure out where a null or undefined value came from,
parentheses and cast expressions are either completely irrelevant, or,
in the case of lvalue-to-rvale cast, straightforwardly lead us in the right
direction when we remove them.

There is a regression that causes a certain diagnostic to appear twice in the
path-notes.cpp test (changed to FIXME). It would be addressed in the next
commit.

Differential revision: https://reviews.llvm.org/D41254

llvm-svn: 321133

clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp

@@ -985,12 +985,8 @@ bool bugreporter::trackNullOrUndefValue(const ExplodedNode *N,
   if (!S || !N)
     return false;
 
-  if (const Expr *Ex = dyn_cast<Expr>(S)) {
-    Ex = Ex->IgnoreParenCasts();
-    const Expr *PeeledEx = peelOffOuterExpr(Ex, N);
-    if (Ex != PeeledEx)
-      S = PeeledEx;
-  }
+  if (const Expr *Ex = dyn_cast<Expr>(S))
+    S = peelOffOuterExpr(Ex, N);
 
   const Expr *Inner = nullptr;
   if (const Expr *Ex = dyn_cast<Expr>(S)) {

clang/test/Analysis/inlining/false-positive-suppression.m

@@ -5,7 +5,7 @@
 
 #define ARC __has_feature(objc_arc)
 
-#if defined(SUPPRESSED) && !ARC
+#ifdef SUPPRESSED
 // expected-no-diagnostics
 #endif
 
@@ -27,9 +27,8 @@ void testNilReceiverHelperA(int *x) {
 
 void testNilReceiverHelperB(int *x) {
   *x = 1;
-// FIXME: Suppression for this case isn't working under ARC. It should.
-#if !defined(SUPPRESSED) || (defined(SUPPRESSED) && ARC)
-  // expected-warning@-3 {{Dereference of null pointer}}
+#if !defined(SUPPRESSED)
+  // expected-warning@-2 {{Dereference of null pointer}}
 #endif
 }
 

clang/test/Analysis/inlining/inline-defensive-checks.c

@@ -197,6 +197,12 @@ void idcTrackConstraintThroughSymbolicRegion(int **x) {
   **x = 7; // expected-warning{{Dereference of null pointer}}
 }
 
+void idcTrackConstraintThroughSymbolicRegionAndParens(int **x) {
+  idc(*x);
+  // FIXME: Should not warn.
+  *(*x) = 7; // expected-warning{{Dereference of null pointer}}
+}
+
 int *idcPlainNull(int coin) {
   if (coin)
     return 0;
@@ -208,3 +214,30 @@ void idcTrackZeroValueThroughSymbolicRegion(int coin, int **x) {
   *x = idcPlainNull(coin);
   **x = 7; // no-warning
 }
+
+void idcTrackZeroValueThroughSymbolicRegionAndParens(int coin, int **x) {
+  *x = idcPlainNull(coin);
+  *(*x) = 7; // no-warning
+}
+
+struct WithInt {
+  int i;
+};
+
+struct WithArray {
+  struct WithInt arr[1];
+};
+
+struct WithArray *idcPlainNullWithArray(int coin) {
+  if (coin)
+    return 0;
+  static struct WithArray S;
+  return &S;
+}
+
+void idcTrackZeroValueThroughSymbolicRegionWithArray(int coin, struct WithArray **s) {
+  *s = idcPlainNullWithArray(coin);
+  (*s)->arr[0].i = 1; // no-warning
+  // Same thing.
+  (*s)->arr->i = 1; // no-warning
+}