Revert "[-Wunsafe-buffer-usage] Group variables associated by pointer assignments"

This reverts commit ee6b08e.

One of the added tests warn-unsafe-buffer-usage-multi-decl-warnings.cpp does
not seem to be deterministic, and seems to be especially problematic on Windows.

Failures of this one test on llvm-clang-x86_64-sie-win:
- https://lab.llvm.org/buildbot/#/builders/216/builds/21758
- https://lab.llvm.org/buildbot/#/builders/216/builds/21761
- https://lab.llvm.org/buildbot/#/builders/216/builds/21762
- https://lab.llvm.org/buildbot/#/builders/216/builds/21765
- https://lab.llvm.org/buildbot/#/builders/216/builds/21770
- https://lab.llvm.org/buildbot/#/builders/216/builds/21771
- https://lab.llvm.org/buildbot/#/builders/216/builds/21773
- https://lab.llvm.org/buildbot/#/builders/216/builds/21776
- https://lab.llvm.org/buildbot/#/builders/216/builds/21777
- https://lab.llvm.org/buildbot/#/builders/216/builds/21778
- https://lab.llvm.org/buildbot/#/builders/216/builds/21779

Other random bot failures:
- https://lab.llvm.org/buildbot/#/builders/65/builds/9821
- https://lab.llvm.org/buildbot/#/builders/65/builds/9822
- https://lab.llvm.org/buildbot/#/builders/65/builds/9824
- https://lab.llvm.org/buildbot/#/builders/119/builds/13440
- https://lab.llvm.org/buildbot/#/builders/119/builds/13442
- https://lab.llvm.org/buildbot/#/builders/119/builds/13444
- https://lab.llvm.org/buildbot/#/builders/119/builds/13445
- https://lab.llvm.org/buildbot/#/builders/60/builds/12156
- https://lab.llvm.org/buildbot/#/builders/60/builds/12157
- https://lab.llvm.org/buildbot/#/builders/60/builds/12160

Author: dyung

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

@@ -19,8 +19,6 @@
 
 namespace clang {
 
-using DefMapTy = llvm::DenseMap<const VarDecl *, std::vector<const VarDecl *>>;
-
 /// The interface that lets the caller handle unsafe buffer usage analysis
 /// results by overriding this class's handle... methods.
 class UnsafeBufferUsageHandler {
@@ -36,12 +34,9 @@ class UnsafeBufferUsageHandler {
   virtual void handleUnsafeOperation(const Stmt *Operation,
                                      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.
-  virtual void handleUnsafeVariableGroup(const VarDecl *Variable,
-                                         const DefMapTy &VarGrpMap,
-                                         FixItList &&Fixes) = 0;
+  /// Invoked when a fix is suggested against a variable.
+  virtual void handleFixableVariable(const VarDecl *Variable,
+                                     FixItList &&List) = 0;
 
   /// Returns a reference to the `Preprocessor`:
   virtual bool isSafeBufferOptOut(const SourceLocation &Loc) const = 0;

clang/include/clang/Analysis/Analyses/UnsafeBufferUsageGadgets.def

@@ -36,7 +36,6 @@ FIXABLE_GADGET(PointerDereference)
 FIXABLE_GADGET(UPCAddressofArraySubscript) // '&DRE[any]' in an Unspecified Pointer Context
 FIXABLE_GADGET(UPCStandalonePointer)
 FIXABLE_GADGET(UPCPreIncrement)            // '++Ptr' in an Unspecified Pointer Context
-FIXABLE_GADGET(PointerAssignment)
 
 #undef FIXABLE_GADGET
 #undef WARNING_GADGET

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -11822,8 +11822,8 @@ def warn_unsafe_buffer_operation : Warning<
   InGroup<UnsafeBufferUsage>, DefaultIgnore;
 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 : Note<
+  "change type of '%0' to '%select{std::span|std::array|std::span::iterator}1' to preserve bounds information">;
 def note_safe_buffer_usage_suggestions_disabled : Note<
   "pass -fsafe-buffer-usage-suggestions to receive code hardening suggestions">;
 def err_loongarch_builtin_requires_la32 : Error<