[analyzer] Allow checkers to supply call stack diagnostic hints for the

BugVisitor DiagnosticPieces.

When checkers create a DiagnosticPieceEvent, they can supply an extra
string, which will be concatenated with the call exit message for every
call on the stack between the diagnostic event and the final bug report.
(This is a simple version, which could be/will be further enhanced.)

For example, this is used in Malloc checker to produce the ",
which allocated memory" in the following example:

static char *malloc_wrapper() { // 2. Entered call from 'use'
    return malloc(12);    // 3. Memory is allocated
}

void use() {
    char *v;
    v = malloc_wrapper(); // 1. Calling 'malloc_wrappers'
        // 4. Returning from 'malloc_wrapper', which allocated memory
}                         // 5. Memory is never released; potential
memory leak

llvm-svn: 152837

1 files changed, 11 insertions, 4 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
index 3f0d3d456e3..e071626eb6a 100644
--- a/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/MallocChecker.cpp
@@ -1249,6 +1249,7 @@ MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N,
 
   const Stmt *S = 0;
   const char *Msg = 0;
+  const char *StackMsg = 0;
 
   // Retrieve the associated statement.
   ProgramPoint ProgLoc = N->getLocation();
@@ -1264,14 +1265,18 @@ MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N,
     return 0;
 
   // Find out if this is an interesting point and what is the kind.
+  // TODO: Replace 'callee' by the function name.
   if (Mode == Normal) {
-    if (isAllocated(RS, RSPrev, S))
+    if (isAllocated(RS, RSPrev, S)) {
       Msg = "Memory is allocated";
-    else if (isReleased(RS, RSPrev, S))
+      StackMsg = ", which allocated memory";
+    } else if (isReleased(RS, RSPrev, S)) {
       Msg = "Memory is released";
-    else if (isReallocFailedCheck(RS, RSPrev, S)) {
+      StackMsg = ", which released memory";
+    } else if (isReallocFailedCheck(RS, RSPrev, S)) {
       Mode = ReallocationFailed;
       Msg = "Reallocation failed";
+      StackMsg = ", where reallocation failed";
     }
 
   // We are in a special mode if a reallocation failed later in the path.
@@ -1291,16 +1296,18 @@ MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N,
     if (!(FunName.equals("realloc") || FunName.equals("reallocf")))
       return 0;
     Msg = "Attempt to reallocate memory";
+    StackMsg = ", which attempted to reallocate memory";
     Mode = Normal;
   }
 
   if (!Msg)
     return 0;
+  assert(StackMsg);
 
   // Generate the extra diagnostic.
   PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
                              N->getLocationContext());
-  return new PathDiagnosticEventPiece(Pos, Msg);
+  return new PathDiagnosticEventPiece(Pos, Msg, true, StackMsg);
 }