[-Wunsafe-buffer-usage] cherry-picks

clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h

@@ -16,14 +16,46 @@
 
 #include "clang/AST/Decl.h"
 #include "clang/AST/Stmt.h"
+#include "llvm/Support/Debug.h"
 
 namespace clang {
 
-using DefMapTy = llvm::DenseMap<const VarDecl *, std::vector<const VarDecl *>>;
+using VarGrpTy = std::vector<const VarDecl *>;
+using VarGrpRef = ArrayRef<const VarDecl *>;
+
+class VariableGroupsManager {
+public:
+  VariableGroupsManager() = default;
+  virtual ~VariableGroupsManager() = default;
+  /// Returns the set of variables (including `Var`) that need to be fixed
+  /// together in one step.
+  ///
+  /// `Var` must be a variable that needs fix (so it must be in a group).
+  /// `HasParm` is an optional argument that will be set to true if the set of
+  /// variables, where `Var` is in, contains parameters.
+  virtual VarGrpRef getGroupOfVar(const VarDecl *Var,
+                                  bool *HasParm = nullptr) const = 0;
+
+  /// Returns the non-empty group of variables that include parameters of the
+  /// analyzing function, if such a group exists.  An empty group, otherwise.
+  virtual VarGrpRef getGroupOfParms() const = 0;
+};
 
 /// The interface that lets the caller handle unsafe buffer usage analysis
 /// results by overriding this class's handle... methods.
 class UnsafeBufferUsageHandler {
+#ifndef NDEBUG
+public:
+  // A self-debugging facility that you can use to notify the user when
+  // suggestions or fixits are incomplete.
+  // Uses std::function to avoid computing the message when it won't
+  // actually be displayed.
+  using DebugNote = std::pair<SourceLocation, std::string>;
+  using DebugNoteList = std::vector<DebugNote>;
+  using DebugNoteByVar = std::map<const VarDecl *, DebugNoteList>;
+  DebugNoteByVar DebugNotesByVar;
+#endif
+
 public:
   UnsafeBufferUsageHandler() = default;
   virtual ~UnsafeBufferUsageHandler() = default;
@@ -37,12 +69,35 @@ class UnsafeBufferUsageHandler {
                                      bool IsRelatedToDecl) = 0;
 
   /// Invoked when a fix is suggested against a variable. This function groups
-  /// all variables that must be fixed together (i.e their types must be changed to the
-  /// same target type to prevent type mismatches) into a single fixit.
+  /// all variables that must be fixed together (i.e their types must be changed
+  /// to the same target type to prevent type mismatches) into a single fixit.
+  ///
+  /// `D` is the declaration of the callable under analysis that owns `Variable`
+  /// and all of its group mates.
   virtual void handleUnsafeVariableGroup(const VarDecl *Variable,
-                                         const DefMapTy &VarGrpMap,
-                                         FixItList &&Fixes) = 0;
+                                         const VariableGroupsManager &VarGrpMgr,
+                                         FixItList &&Fixes, const Decl *D) = 0;
 
+#ifndef NDEBUG
+public:
+  bool areDebugNotesRequested() {
+    DEBUG_WITH_TYPE("SafeBuffers", return true);
+    return false;
+  }
+
+  void addDebugNoteForVar(const VarDecl *VD, SourceLocation Loc,
+                          std::string Text) {
+    if (areDebugNotesRequested())
+      DebugNotesByVar[VD].push_back(std::make_pair(Loc, Text));
+  }
+
+  void clearDebugNotes() {
+    if (areDebugNotesRequested())
+      DebugNotesByVar.clear();
+  }
+#endif
+
+public:
   /// Returns a reference to the `Preprocessor`:
   virtual bool isSafeBufferOptOut(const SourceLocation &Loc) const = 0;
 

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -11965,8 +11965,17 @@ def note_unsafe_buffer_operation : Note<
   "used%select{| in pointer arithmetic| in buffer access}0 here">;
 def note_unsafe_buffer_variable_fixit_group : Note<
   "change type of %0 to '%select{std::span|std::array|std::span::iterator}1' to preserve bounds information%select{|, and change %2 to '%select{std::span|std::array|std::span::iterator}1' to propagate bounds information between them}3">;
+def note_unsafe_buffer_variable_fixit_together : Note<
+  "change type of %0 to '%select{std::span|std::array|std::span::iterator}1' to preserve bounds information"
+  "%select{|, and change %2 to safe types to make function %4 bounds-safe}3">;
 def note_safe_buffer_usage_suggestions_disabled : Note<
   "pass -fsafe-buffer-usage-suggestions to receive code hardening suggestions">;
+#ifndef NDEBUG
+// Not a user-facing diagnostic. Useful for debugging false negatives in
+// -fsafe-buffer-usage-suggestions (i.e. lack of -Wunsafe-buffer-usage fixits).
+def note_safe_buffer_debug_mode : Note<"safe buffers debug: %0">;
+#endif
+
 def err_loongarch_builtin_requires_la32 : Error<
   "this builtin requires target: loongarch32">;