From 2d46f4dc297b32eff154a26c0e3bc16b6c66b78c Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Sat, 20 Mar 2010 01:17:30 +0000
Subject: [PATCH] Augment path diagnostics to include displaying when a message
 expression is not evaluated because the receiver is nil.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99024 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../clang/Checker/BugReporter/BugReporter.h   |  2 +
 lib/Checker/BugReporter.cpp                   |  2 +
 lib/Checker/BugReporterVisitors.cpp           | 51 +++++++++++++++++--
 3 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/include/clang/Checker/BugReporter/BugReporter.h b/include/clang/Checker/BugReporter/BugReporter.h
index 6c41668cce..da91e126f0 100644
--- a/include/clang/Checker/BugReporter/BugReporter.h
+++ b/include/clang/Checker/BugReporter/BugReporter.h
@@ -467,6 +467,8 @@ void registerTrackNullOrUndefValue(BugReporterContext& BRC, const void *stmt,
 void registerFindLastStore(BugReporterContext& BRC, const void *memregion,
                            const ExplodedNode *N);
 
+void registerNilReceiverVisitor(BugReporterContext &BRC);
+
 
 } // end namespace clang::bugreporter
 
diff --git a/lib/Checker/BugReporter.cpp b/lib/Checker/BugReporter.cpp
index 0cf593b260..c7438447bb 100644
--- a/lib/Checker/BugReporter.cpp
+++ b/lib/Checker/BugReporter.cpp
@@ -1613,7 +1613,9 @@ void GRBugReporter::GeneratePathDiagnostic(PathDiagnostic& PD,
   else
     return;
 
+  // Register node visitors.
   R->registerInitialVisitors(PDB, N);
+  bugreporter::registerNilReceiverVisitor(PDB);
 
   switch (PDB.getGenerationScheme()) {
     case PathDiagnosticClient::Extensive:
diff --git a/lib/Checker/BugReporterVisitors.cpp b/lib/Checker/BugReporterVisitors.cpp
index 6cf41b14dc..6cf6d92efb 100644
--- a/lib/Checker/BugReporterVisitors.cpp
+++ b/lib/Checker/BugReporterVisitors.cpp
@@ -103,7 +103,6 @@ public:
       const ExplodedNode *Node = N, *Last = NULL;
 
       for ( ; Node ; Last = Node, Node = Node->getFirstPred()) {
-
         if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
           if (const PostStmt *P = Node->getLocationAs<PostStmt>())
             if (const DeclStmt *DS = P->getStmtAs<DeclStmt>())
@@ -248,7 +247,6 @@ public:
     // Check if in the previous state it was feasible for this constraint
     // to *not* be true.
     if (PrevN->getState()->Assume(Constraint, !Assumption)) {
-
       isSatisfied = true;
 
       // As a sanity check, make sure that the negation of the constraint
@@ -259,8 +257,8 @@ public:
 
       // We found the transition point for the constraint.  We now need to
       // pretty-print the constraint. (work-in-progress)
-      std::string sbuf;
-      llvm::raw_string_ostream os(sbuf);
+      llvm::SmallString<256> sbuf;
+      llvm::raw_svector_ostream os(sbuf);
 
       if (isa<Loc>(Constraint)) {
         os << "Assuming pointer value is ";
@@ -365,3 +363,48 @@ void clang::bugreporter::registerFindLastStore(BugReporterContext& BRC,
 
   BRC.addVisitor(new FindLastStoreBRVisitor(V, R));
 }
+
+namespace {
+class NilReceiverVisitor : public BugReporterVisitor {
+public:
+  NilReceiverVisitor() {}
+
+  PathDiagnosticPiece* VisitNode(const ExplodedNode *N,
+                                 const ExplodedNode *PrevN,
+                                 BugReporterContext& BRC) {
+
+    const PostStmt *P = N->getLocationAs<PostStmt>();
+    if (!P)
+      return 0;
+    const ObjCMessageExpr *ME = P->getStmtAs<ObjCMessageExpr>();
+    if (!ME)
+      return 0;
+    const Expr *Receiver = ME->getReceiver();
+    if (!Receiver)
+      return 0;
+    const GRState *state = N->getState();
+    const SVal &V = state->getSVal(Receiver);
+    const DefinedOrUnknownSVal *DV = dyn_cast<DefinedOrUnknownSVal>(&V);
+    if (!DV)
+      return 0;
+
+    state = state->Assume(*DV, true);
+    if (state)
+      return 0;
+
+    // The receiver was nil, and hence the method was skipped.
+    // Register a BugReporterVisitor to issue a message telling us how
+    // the receiver was null.
+    bugreporter::registerTrackNullOrUndefValue(BRC, Receiver, N);
+
+    //Issue a message saying that the method was skipped.
+    PathDiagnosticLocation L(Receiver, BRC.getSourceManager());
+    return new PathDiagnosticEventPiece(L, "No method actually called "
+                                           "because the receiver is nil");
+  }
+};
+} // end anonymous namespace
+
+void clang::bugreporter::registerNilReceiverVisitor(BugReporterContext &BRC) {
+  BRC.addVisitor(new NilReceiverVisitor());
+}
-- 
2.50.1