[-Wunsafe-buffer-usage] Group parameter fix-its

For a function `F` whose parameters need to be fixed, we group fix-its
of F's parameters together so that either all of the parameters get
fixed or none of them gets fixed.

Reviewed by: NoQ (Artem Dergachev), t-rasmud (Rashmi Mudduluru), jkorous (Jan Korous)

Differential revision: https://reviews.llvm.org/D153059

Author: ziqingluo-90

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

@@ -31,7 +31,10 @@ class VariableGroupsManager {
   /// together in one step.
   ///
   /// `Var` must be a variable that needs fix (so it must be in a group).
-  virtual VarGrpRef getGroupOfVar(const VarDecl *Var) const =0;
+  /// `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;
 };
 
 /// The interface that lets the caller handle unsafe buffer usage analysis
@@ -62,11 +65,14 @@ 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 VariableGroupsManager &VarGrpMgr,
-                                         FixItList &&Fixes) = 0;
+                                         FixItList &&Fixes, const Decl *D) = 0;
 
 #ifndef NDEBUG
 public:

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -11916,6 +11916,9 @@ 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