[NFC][analyzer] Conversion to CheckerFamily: CStringChecker

NagyDonat · NagyDonat · commit 3422f5acd8fe · 2025-07-28T17:20:19.000+02:00
This commit converts the class CStringChecker to the checker family
framework and slightly simplifies the implementation.

This commit is NFC and preserves the confused garbage descriptions and
categories of the bug types (which was inherited from old mistakes). I'm
planning to clean that up in a follow-up commit.
diff --git a/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CStringChecker.cpp
@@ -78,35 +78,30 @@ static QualType getCharPtrType(ASTContext &Ctx, CharKind CK) {
                                                     : Ctx.WideCharTy);
 }
 
-class CStringChecker : public Checker< eval::Call,
-                                         check::PreStmt<DeclStmt>,
-                                         check::LiveSymbols,
-                                         check::DeadSymbols,
-                                         check::RegionChanges
-                                         > {
-  mutable std::unique_ptr<BugType> BT_Null, BT_Bounds, BT_Overlap,
-      BT_NotCString, BT_AdditionOverflow, BT_UninitRead;
-
+class CStringChecker
+    : public CheckerFamily<eval::Call, check::PreStmt<DeclStmt>,
+                           check::LiveSymbols, check::DeadSymbols,
+                           check::RegionChanges> {
   mutable const char *CurrentFunctionDescription = nullptr;
 
 public:
-  /// The filter is used to filter out the diagnostics which are not enabled by
-  /// the user.
-  struct CStringChecksFilter {
-    bool CheckCStringNullArg = false;
-    bool CheckCStringOutOfBounds = false;
-    bool CheckCStringBufferOverlap = false;
-    bool CheckCStringNotNullTerm = false;
-    bool CheckCStringUninitializedRead = false;
-
-    CheckerNameRef CheckNameCStringNullArg;
-    CheckerNameRef CheckNameCStringOutOfBounds;
-    CheckerNameRef CheckNameCStringBufferOverlap;
-    CheckerNameRef CheckNameCStringNotNullTerm;
-    CheckerNameRef CheckNameCStringUninitializedRead;
-  };
-
-  CStringChecksFilter Filter;
+  // FIXME: The bug types emitted by this checker family have confused garbage
+  // in their Description and Category fields (e.g. `categories::UnixAPI` is
+  // passed as the description in several cases and `uninitialized` is mistyped
+  // as `unitialized`). This should be cleaned up.
+  CheckerFrontendWithBugType NullArg{categories::UnixAPI};
+  CheckerFrontendWithBugType OutOfBounds{"Out-of-bound array access"};
+  CheckerFrontendWithBugType BufferOverlap{categories::UnixAPI,
+                                           "Improper arguments"};
+  CheckerFrontendWithBugType NotNullTerm{categories::UnixAPI};
+  CheckerFrontendWithBugType UninitializedRead{
+      "Accessing unitialized/garbage values"};
+
+  // FIXME: This bug type should be removed because it is only emitted in a
+  // situation that is practically impossible.
+  const BugType AdditionOverflow{&OutOfBounds, "API"};
+
+  StringRef getDebugTag() const override { return "MallocChecker"; }
 
   static void *getTag() { static int tag; return &tag; }
 
@@ -384,7 +379,7 @@ ProgramStateRef CStringChecker::checkNonNull(CheckerContext &C,
       assumeZero(C, State, l, Arg.Expression->getType());
 
   if (stateNull && !stateNonNull) {
-    if (Filter.CheckCStringNullArg) {
+    if (NullArg.isEnabled()) {
       SmallString<80> buf;
       llvm::raw_svector_ostream OS(buf);
       assert(CurrentFunctionDescription);
@@ -468,7 +463,7 @@ ProgramStateRef CStringChecker::checkInit(CheckerContext &C,
     return State;
 
   // Ensure that we wouldn't read uninitialized value.
-  if (Filter.CheckCStringUninitializedRead &&
+  if (UninitializedRead.isEnabled() &&
       State->getSVal(*FirstElementVal).isUndef()) {
     llvm::SmallString<258> Buf;
     llvm::raw_svector_ostream OS(Buf);
@@ -524,7 +519,7 @@ ProgramStateRef CStringChecker::checkInit(CheckerContext &C,
   if (!isa<Loc>(LastElementVal))
     return State;
 
-  if (Filter.CheckCStringUninitializedRead &&
+  if (UninitializedRead.isEnabled() &&
       State->getSVal(LastElementVal.castAs<Loc>()).isUndef()) {
     const llvm::APSInt *IdxInt = LastIdx.getAsInteger();
     // If we can't get emit a sensible last element index, just bail out --
@@ -584,7 +579,7 @@ ProgramStateRef CStringChecker::CheckLocation(CheckerContext &C,
     // These checks are either enabled by the CString out-of-bounds checker
     // explicitly or implicitly by the Malloc checker.
     // In the latter case we only do modeling but do not emit warning.
-    if (!Filter.CheckCStringOutOfBounds)
+    if (!OutOfBounds.isEnabled())
       return nullptr;
 
     // Emit a bug report.
@@ -620,7 +615,7 @@ CStringChecker::CheckBufferAccess(CheckerContext &C, ProgramStateRef State,
     return nullptr;
 
   // If out-of-bounds checking is turned off, skip the rest.
-  if (!Filter.CheckCStringOutOfBounds)
+  if (!OutOfBounds.isEnabled())
     return State;
 
   SVal BufStart =
@@ -670,7 +665,7 @@ ProgramStateRef CStringChecker::CheckOverlap(CheckerContext &C,
                                              SizeArgExpr Size, AnyArgExpr First,
                                              AnyArgExpr Second,
                                              CharKind CK) const {
-  if (!Filter.CheckCStringBufferOverlap)
+  if (!BufferOverlap.isEnabled())
     return state;
 
   // Do a simple check for overlap: if the two arguments are from the same
@@ -789,13 +784,9 @@ void CStringChecker::emitOverlapBug(CheckerContext &C, ProgramStateRef state,
   if (!N)
     return;
 
-  if (!BT_Overlap)
-    BT_Overlap.reset(new BugType(Filter.CheckNameCStringBufferOverlap,
-                                 categories::UnixAPI, "Improper arguments"));
-
   // Generate a report for this bug.
   auto report = std::make_unique<PathSensitiveBugReport>(
-      *BT_Overlap, "Arguments must not be overlapping buffers", N);
+      BufferOverlap, "Arguments must not be overlapping buffers", N);
   report->addRange(First->getSourceRange());
   report->addRange(Second->getSourceRange());
 
@@ -805,15 +796,8 @@ void CStringChecker::emitOverlapBug(CheckerContext &C, ProgramStateRef state,
 void CStringChecker::emitNullArgBug(CheckerContext &C, ProgramStateRef State,
                                     const Stmt *S, StringRef WarningMsg) const {
   if (ExplodedNode *N = C.generateErrorNode(State)) {
-    if (!BT_Null) {
-      // FIXME: This call uses the string constant 'categories::UnixAPI' as the
-      // description of the bug; it should be replaced by a real description.
-      BT_Null.reset(
-          new BugType(Filter.CheckNameCStringNullArg, categories::UnixAPI));
-    }
-
     auto Report =
-        std::make_unique<PathSensitiveBugReport>(*BT_Null, WarningMsg, N);
+        std::make_unique<PathSensitiveBugReport>(NullArg, WarningMsg, N);
     Report->addRange(S->getSourceRange());
     if (const auto *Ex = dyn_cast<Expr>(S))
       bugreporter::trackExpressionValue(N, Ex, *Report);
@@ -826,12 +810,8 @@ void CStringChecker::emitUninitializedReadBug(CheckerContext &C,
                                               const Expr *E, const MemRegion *R,
                                               StringRef Msg) const {
   if (ExplodedNode *N = C.generateErrorNode(State)) {
-    if (!BT_UninitRead)
-      BT_UninitRead.reset(new BugType(Filter.CheckNameCStringUninitializedRead,
-                                      "Accessing unitialized/garbage values"));
-
     auto Report =
-        std::make_unique<PathSensitiveBugReport>(*BT_UninitRead, Msg, N);
+        std::make_unique<PathSensitiveBugReport>(UninitializedRead, Msg, N);
     Report->addNote("Other elements might also be undefined",
                     Report->getLocation());
     Report->addRange(E->getSourceRange());
@@ -845,17 +825,11 @@ void CStringChecker::emitOutOfBoundsBug(CheckerContext &C,
                                         ProgramStateRef State, const Stmt *S,
                                         StringRef WarningMsg) const {
   if (ExplodedNode *N = C.generateErrorNode(State)) {
-    if (!BT_Bounds)
-      BT_Bounds.reset(new BugType(Filter.CheckCStringOutOfBounds
-                                      ? Filter.CheckNameCStringOutOfBounds
-                                      : Filter.CheckNameCStringNullArg,
-                                  "Out-of-bound array access"));
-
     // FIXME: It would be nice to eventually make this diagnostic more clear,
     // e.g., by referencing the original declaration or by saying *why* this
     // reference is outside the range.
     auto Report =
-        std::make_unique<PathSensitiveBugReport>(*BT_Bounds, WarningMsg, N);
+        std::make_unique<PathSensitiveBugReport>(OutOfBounds, WarningMsg, N);
     Report->addRange(S->getSourceRange());
     C.emitReport(std::move(Report));
   }
@@ -865,15 +839,8 @@ void CStringChecker::emitNotCStringBug(CheckerContext &C, ProgramStateRef State,
                                        const Stmt *S,
                                        StringRef WarningMsg) const {
   if (ExplodedNode *N = C.generateNonFatalErrorNode(State)) {
-    if (!BT_NotCString) {
-      // FIXME: This call uses the string constant 'categories::UnixAPI' as the
-      // description of the bug; it should be replaced by a real description.
-      BT_NotCString.reset(
-          new BugType(Filter.CheckNameCStringNotNullTerm, categories::UnixAPI));
-    }
-
     auto Report =
-        std::make_unique<PathSensitiveBugReport>(*BT_NotCString, WarningMsg, N);
+        std::make_unique<PathSensitiveBugReport>(NotNullTerm, WarningMsg, N);
 
     Report->addRange(S->getSourceRange());
     C.emitReport(std::move(Report));
@@ -883,22 +850,14 @@ void CStringChecker::emitNotCStringBug(CheckerContext &C, ProgramStateRef State,
 void CStringChecker::emitAdditionOverflowBug(CheckerContext &C,
                                              ProgramStateRef State) const {
   if (ExplodedNode *N = C.generateErrorNode(State)) {
-    if (!BT_AdditionOverflow) {
-      // FIXME: This call uses the word "API" as the description of the bug;
-      // it should be replaced by a better error message (if this unlikely
-      // situation continues to exist as a separate bug type).
-      BT_AdditionOverflow.reset(
-          new BugType(Filter.CheckNameCStringOutOfBounds, "API"));
-    }
-
     // This isn't a great error message, but this should never occur in real
     // code anyway -- you'd have to create a buffer longer than a size_t can
     // represent, which is sort of a contradiction.
     const char *WarningMsg =
         "This expression will create a string whose length is too big to "
         "be represented as a size_t";
 
-    auto Report = std::make_unique<PathSensitiveBugReport>(*BT_AdditionOverflow,
+    auto Report = std::make_unique<PathSensitiveBugReport>(AdditionOverflow,
                                                            WarningMsg, N);
     C.emitReport(std::move(Report));
   }
@@ -909,7 +868,7 @@ ProgramStateRef CStringChecker::checkAdditionOverflow(CheckerContext &C,
                                                      NonLoc left,
                                                      NonLoc right) const {
   // If out-of-bounds checking is turned off, skip the rest.
-  if (!Filter.CheckCStringOutOfBounds)
+  if (!OutOfBounds.isEnabled())
     return state;
 
   // If a previous check has failed, propagate the failure.
@@ -1048,7 +1007,7 @@ SVal CStringChecker::getCStringLength(CheckerContext &C, ProgramStateRef &state,
     // C string. In the context of locations, the only time we can issue such
     // a warning is for labels.
     if (std::optional<loc::GotoLabel> Label = Buf.getAs<loc::GotoLabel>()) {
-      if (Filter.CheckCStringNotNullTerm) {
+      if (NotNullTerm.isEnabled()) {
         SmallString<120> buf;
         llvm::raw_svector_ostream os(buf);
         assert(CurrentFunctionDescription);
@@ -1110,7 +1069,7 @@ SVal CStringChecker::getCStringLength(CheckerContext &C, ProgramStateRef &state,
     // Other regions (mostly non-data) can't have a reliable C string length.
     // In this case, an error is emitted and UndefinedVal is returned.
     // The caller should always be prepared to handle this case.
-    if (Filter.CheckCStringNotNullTerm) {
+    if (NotNullTerm.isEnabled()) {
       SmallString<120> buf;
       llvm::raw_svector_ostream os(buf);
 
@@ -2873,24 +2832,27 @@ void CStringChecker::checkDeadSymbols(SymbolReaper &SR,
 }
 
 void ento::registerCStringModeling(CheckerManager &Mgr) {
-  Mgr.registerChecker<CStringChecker>();
+  // Other checker relies on the modeling implemented in this checker family,
+  // so this "modeling checker" can register the 'CStringChecker' backend for
+  // its callbacks without enabling any of its frontends.
+  Mgr.getChecker<CStringChecker>();
 }
 
-bool ento::shouldRegisterCStringModeling(const CheckerManager &mgr) {
+bool ento::shouldRegisterCStringModeling(const CheckerManager &) {
   return true;
 }
 
-#define REGISTER_CHECKER(name)                                                 \
-  void ento::register##name(CheckerManager &mgr) {                             \
-    CStringChecker *checker = mgr.getChecker<CStringChecker>();                \
-    checker->Filter.Check##name = true;                                        \
-    checker->Filter.CheckName##name = mgr.getCurrentCheckerName();             \
+#define REGISTER_CHECKER(NAME)                                                 \
+  void ento::registerCString##NAME(CheckerManager &Mgr) {                      \
+    Mgr.getChecker<CStringChecker>()->NAME.enable(Mgr);                        \
   }                                                                            \
                                                                                \
-  bool ento::shouldRegister##name(const CheckerManager &mgr) { return true; }
+  bool ento::shouldRegisterCString##NAME(const CheckerManager &) {             \
+    return true;                                                               \
+  }
 
-REGISTER_CHECKER(CStringNullArg)
-REGISTER_CHECKER(CStringOutOfBounds)
-REGISTER_CHECKER(CStringBufferOverlap)
-REGISTER_CHECKER(CStringNotNullTerm)
-REGISTER_CHECKER(CStringUninitializedRead)
+REGISTER_CHECKER(NullArg)
+REGISTER_CHECKER(OutOfBounds)
+REGISTER_CHECKER(BufferOverlap)
+REGISTER_CHECKER(NotNullTerm)
+REGISTER_CHECKER(UninitializedRead)
