1 files changed, 49 insertions, 13 deletions

diff --git a/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
index 1077ceb6288e..7c51673422a0 100644
--- a/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
+++ b/contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/EnumCastOutOfRangeChecker.cpp
@@ -22,10 +22,12 @@
 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "llvm/Support/FormatVariadic.h"
 #include <optional>
 
 using namespace clang;
 using namespace ento;
+using llvm::formatv;
 
 namespace {
 // This evaluator checks two SVals for equality. The first SVal is provided via
@@ -58,8 +60,9 @@ public:
 // Being conservative, it does not warn if there is slight possibility the
 // value can be matching.
 class EnumCastOutOfRangeChecker : public Checker<check::PreStmt<CastExpr>> {
-  mutable std::unique_ptr<BuiltinBug> EnumValueCastOutOfRange;
-  void reportWarning(CheckerContext &C) const;
+  mutable std::unique_ptr<BugType> EnumValueCastOutOfRange;
+  void reportWarning(CheckerContext &C, const CastExpr *CE,
+                     const EnumDecl *E) const;
 
 public:
   void checkPreStmt(const CastExpr *CE, CheckerContext &C) const;
@@ -72,21 +75,43 @@ EnumValueVector getDeclValuesForEnum(const EnumDecl *ED) {
   EnumValueVector DeclValues(
       std::distance(ED->enumerator_begin(), ED->enumerator_end()));
   llvm::transform(ED->enumerators(), DeclValues.begin(),
-                 [](const EnumConstantDecl *D) { return D->getInitVal(); });
+                  [](const EnumConstantDecl *D) { return D->getInitVal(); });
   return DeclValues;
 }
 } // namespace
 
-void EnumCastOutOfRangeChecker::reportWarning(CheckerContext &C) const {
+void EnumCastOutOfRangeChecker::reportWarning(CheckerContext &C,
+                                              const CastExpr *CE,
+                                              const EnumDecl *E) const {
+  assert(E && "valid EnumDecl* is expected");
   if (const ExplodedNode *N = C.generateNonFatalErrorNode()) {
     if (!EnumValueCastOutOfRange)
       EnumValueCastOutOfRange.reset(
-          new BuiltinBug(this, "Enum cast out of range",
-                         "The value provided to the cast expression is not in "
-                         "the valid range of values for the enum"));
-    C.emitReport(std::make_unique<PathSensitiveBugReport>(
-        *EnumValueCastOutOfRange, EnumValueCastOutOfRange->getDescription(),
-        N));
+          new BugType(this, "Enum cast out of range"));
+
+    std::string ValueStr = "", NameStr = "the enum";
+
+    // Try to add details to the message:
+    const auto ConcreteValue =
+        C.getSVal(CE->getSubExpr()).getAs<nonloc::ConcreteInt>();
+    if (ConcreteValue) {
+      ValueStr = formatv(" '{0}'", ConcreteValue->getValue());
+    }
+    if (StringRef EnumName{E->getName()}; !EnumName.empty()) {
+      NameStr = formatv("'{0}'", EnumName);
+    }
+
+    std::string Msg = formatv("The value{0} provided to the cast expression is "
+                              "not in the valid range of values for {1}",
+                              ValueStr, NameStr);
+
+    auto BR = std::make_unique<PathSensitiveBugReport>(*EnumValueCastOutOfRange,
+                                                       Msg, N);
+    bugreporter::trackExpressionValue(N, CE->getSubExpr(), *BR);
+    BR->addNote("enum declared here",
+                PathDiagnosticLocation::create(E, C.getSourceManager()),
+                {E->getSourceRange()});
+    C.emitReport(std::move(BR));
   }
 }
 
@@ -129,14 +154,25 @@ void EnumCastOutOfRangeChecker::checkPreStmt(const CastExpr *CE,
   const EnumDecl *ED = T->castAs<EnumType>()->getDecl();
 
   EnumValueVector DeclValues = getDeclValuesForEnum(ED);
+
+  // If the declarator list is empty, bail out.
+  // Every initialization an enum with a fixed underlying type but without any
+  // enumerators would produce a warning if we were to continue at this point.
+  // The most notable example is std::byte in the C++17 standard library.
+  // TODO: Create heuristics to bail out when the enum type is intended to be
+  // used to store combinations of flag values (to mitigate the limitation
+  // described in the docs).
+  if (DeclValues.size() == 0)
+    return;
+
   // Check if any of the enum values possibly match.
-  bool PossibleValueMatch = llvm::any_of(
-      DeclValues, ConstraintBasedEQEvaluator(C, *ValueToCast));
+  bool PossibleValueMatch =
+      llvm::any_of(DeclValues, ConstraintBasedEQEvaluator(C, *ValueToCast));
 
   // If there is no value that can possibly match any of the enum values, then
   // warn.
   if (!PossibleValueMatch)
-    reportWarning(C);
+    reportWarning(C, CE, ED);
 }
 
 void ento::registerEnumCastOutOfRangeChecker(CheckerManager &mgr) {