From 12182a0344c11970f307bc79eeb102633561b680 Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Mon, 22 Mar 2010 22:16:26 +0000
Subject: [PATCH] Improve the diagnostics for the UndefinedAssignmentChecker
 when an uninitialized value is used in the LHS of a compound assignment.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99221 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Checker/UndefinedAssignmentChecker.cpp | 38 +++++++++++++++-------
 test/Analysis/uninit-vals-ps-region.m      |  7 ++++
 2 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/lib/Checker/UndefinedAssignmentChecker.cpp b/lib/Checker/UndefinedAssignmentChecker.cpp
index 7c33c1d392..9f17ef126d 100644
--- a/lib/Checker/UndefinedAssignmentChecker.cpp
+++ b/lib/Checker/UndefinedAssignmentChecker.cpp
@@ -53,27 +53,43 @@ void UndefinedAssignmentChecker::PreVisitBind(CheckerContext &C,
   if (!N)
     return;
 
+  const char *str = "Assigned value is garbage or undefined";
+
   if (!BT)
-    BT = new BuiltinBug("Assigned value is garbage or undefined");
+    BT = new BuiltinBug(str);
 
   // Generate a report for this bug.
-  EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName(), N);
+  const Expr *ex = 0;
 
-  if (AssignE) {
-    const Expr *ex = 0;
+  while (AssignE) {
+    if (const BinaryOperator *B = dyn_cast<BinaryOperator>(AssignE)) {
+      if (B->isCompoundAssignmentOp()) {
+        const GRState *state = C.getState();
+        if (state->getSVal(B->getLHS()).isUndef()) {
+          str = "The left expression of the compound assignment is an "
+                "uninitialized value. The computed value will also be garbage";
+          ex = B->getLHS();
+          break;
+        }
+      }
 
-    if (const BinaryOperator *B = dyn_cast<BinaryOperator>(AssignE))
       ex = B->getRHS();
-    else if (const DeclStmt *DS = dyn_cast<DeclStmt>(AssignE)) {
+      break;
+    }
+
+    if (const DeclStmt *DS = dyn_cast<DeclStmt>(AssignE)) {
       const VarDecl* VD = dyn_cast<VarDecl>(DS->getSingleDecl());
       ex = VD->getInit();
     }
-    if (ex) {
-      R->addRange(ex->getSourceRange());
-      R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, ex);
-    }
+
+    break;
   }
 
+  EnhancedBugReport *R = new EnhancedBugReport(*BT, str, N);
+  if (ex) {
+    R->addRange(ex->getSourceRange());
+    R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, ex);
+  }
   C.EmitReport(R);
-}  
+}
 
diff --git a/test/Analysis/uninit-vals-ps-region.m b/test/Analysis/uninit-vals-ps-region.m
index 7e2fff9db5..69c1ecd1e3 100644
--- a/test/Analysis/uninit-vals-ps-region.m
+++ b/test/Analysis/uninit-vals-ps-region.m
@@ -59,4 +59,11 @@ void testFoo(Foo *o) {
   [o passVal:x]; // expected-warning{{Passed-by-value struct argument contains uninitialized data (e.g., field: 'x')}}
 }
 
+// Test case from <rdar://problem/7780304>.  That shows an uninitialized value
+// being used in the LHS of a compound assignment.
+void rdar_7780304() {
+  typedef struct s_r7780304 { int x; } s_r7780304;
+  s_r7780304 b;
+  b.x |= 1; // expected-warning{{The left expression of the compound assignment is an uninitialized value. The computed value will also be garbage}}
+}
 
-- 
2.40.0