[clang][analyzer] Display notes in StdLibraryFunctionsChecker only if interesting

The note tag that was previously added in all cases when a standard function call
is found is displayed now only if the function call (return value) is "interesting".
This results in less unneeded notes but some of the previously good notes disappear
too. This is because interestingness is not always set as it should be.

Reviewed By: donat.nagy

Differential Revision: https://reviews.llvm.org/D153776

1 files changed, 12 insertions, 6 deletions

diff --git a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
index 8d4fb12..1fb248b 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StdLibraryFunctionsChecker.cpp
@@ -835,6 +835,7 @@ private:
 
     for (ArgNo ArgN : VC->getArgsToTrack()) {
       bugreporter::trackExpressionValue(N, Call.getArgExpr(ArgN), *R);
+      R->markInteresting(Call.getArgSVal(ArgN));
       // All tracked arguments are important, highlight them.
       R->addRange(Call.getArgSourceRange(ArgN));
     }
@@ -1298,6 +1299,7 @@ void StdLibraryFunctionsChecker::checkPostCall(const CallEvent &Call,
     // StdLibraryFunctionsChecker.
     ExplodedNode *Pred = Node;
     if (!Case.getNote().empty()) {
+      const SVal RV = Call.getReturnValue();
       // If there is a description for this execution branch (summary case),
       // use it as a note tag.
       std::string Note =
@@ -1305,7 +1307,7 @@ void StdLibraryFunctionsChecker::checkPostCall(const CallEvent &Call,
                         cast<NamedDecl>(Call.getDecl())->getDeclName());
       if (Summary.getInvalidationKd() == EvalCallAsPure) {
         const NoteTag *Tag = C.getNoteTag(
-            [Node, Note](PathSensitiveBugReport &BR) -> std::string {
+            [Node, Note, RV](PathSensitiveBugReport &BR) -> std::string {
               // Try to omit the note if we know in advance which branch is
               // taken (this means, only one branch exists).
               // This check is performed inside the lambda, after other
@@ -1316,18 +1318,22 @@ void StdLibraryFunctionsChecker::checkPostCall(const CallEvent &Call,
               // split that was performed by another checker (and can not find
               // the successors). This is why this check is only used in the
               // EvalCallAsPure case.
-              if (Node->succ_size() > 1)
+              if (BR.isInteresting(RV) && Node->succ_size() > 1)
                 return Note;
               return "";
-            },
-            /*IsPrunable=*/true);
+            });
         Pred = C.addTransition(NewState, Pred, Tag);
       } else {
-        const NoteTag *Tag = C.getNoteTag(Note, /*IsPrunable=*/true);
+        const NoteTag *Tag =
+            C.getNoteTag([Note, RV](PathSensitiveBugReport &BR) -> std::string {
+              if (BR.isInteresting(RV))
+                return Note;
+              return "";
+            });
         Pred = C.addTransition(NewState, Pred, Tag);
       }
       if (!Pred)
-        break;
+        continue;
     }
 
     // If we can get a note tag for the errno change, add this additionally to