Revert "[clang] Warn [[clang::lifetimebound]] misusages on types (#118281)"

Temporarily revert the patch to give downstream teams some time to clean up their codebases.

This reverts commit 4849d59.

Author: hokein

clang/docs/ReleaseNotes.rst

@@ -139,7 +139,7 @@ C++ Specific Potentially Breaking Changes
     // Fixed version:
     unsigned operator""_udl_name(unsigned long long);
 
-- Clang will now produce an error diagnostic when ``[[clang::lifetimebound]]`` is
+- Clang will now produce an error diagnostic when [[clang::lifetimebound]] is
   applied on a parameter or an implicit object parameter of a function that
   returns void. This was previously ignored and had no effect. (#GH107556)
 
@@ -148,21 +148,6 @@ C++ Specific Potentially Breaking Changes
     // Now diagnoses with an error.
     void f(int& i [[clang::lifetimebound]]);
 
-- Clang will now produce an error diagnostic when ``[[clang::lifetimebound]]``
-  is applied on a type (instead of a function parameter or an implicit object
-  parameter); this includes the case when the attribute is specified for an
-  unnamed function parameter. These were previously ignored and had no effect.
-  (#GH118281)
-
-  .. code-block:: c++
-
-    // Now diagnoses with an error.
-    int* [[clang::lifetimebound]] x;
-    // Now diagnoses with an error.
-    void f(int* [[clang::lifetimebound]] i);
-    // Now diagnoses with an error.
-    void g(int* [[clang::lifetimebound]]);
-
 - Clang now rejects all field accesses on null pointers in constant expressions. The following code
   used to work but will now be rejected:
 

clang/lib/Sema/SemaType.cpp

@@ -8612,11 +8612,7 @@ static void HandleLifetimeBoundAttr(TypeProcessingState &State,
     CurType = State.getAttributedType(
         createSimpleAttr<LifetimeBoundAttr>(State.getSema().Context, Attr),
         CurType, CurType);
-    return;
   }
-  State.getSema().Diag(Attr.getLoc(), diag::err_attribute_wrong_decl_type_str)
-      << Attr << Attr.isRegularKeywordAttribute()
-      << "parameters and implicit object parameters";
 }
 
 static void HandleLifetimeCaptureByAttr(TypeProcessingState &State,

clang/test/SemaCXX/attr-lifetimebound.cpp

@@ -9,25 +9,11 @@ namespace usage_invalid {
     ~A() [[clang::lifetimebound]]; // expected-error {{cannot be applied to a destructor}}
     static int *static_class_member() [[clang::lifetimebound]]; // expected-error {{static member function has no implicit object parameter}}
     int *explicit_object(this A&) [[clang::lifetimebound]]; // expected-error {{explicit object member function has no implicit object parameter}}
-    int attr_on_var [[clang::lifetimebound]]; // expected-error {{only applies to parameters and implicit object parameters}}
-    int [[clang::lifetimebound]] attr_on_int; // expected-error {{cannot be applied to types}}
-    int * [[clang::lifetimebound]] attr_on_int_ptr; // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-    int * [[clang::lifetimebound]] * attr_on_int_ptr_ptr; // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-    int (* [[clang::lifetimebound]] attr_on_func_ptr)(); // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
+    int not_function [[clang::lifetimebound]]; // expected-error {{only applies to parameters and implicit object parameters}}
+    int [[clang::lifetimebound]] also_not_function; // expected-error {{cannot be applied to types}}
     void void_return_member() [[clang::lifetimebound]]; // expected-error {{'lifetimebound' attribute cannot be applied to an implicit object parameter of a function that returns void; did you mean 'lifetime_capture_by(X)'}}
   };
   int *attr_with_param(int &param [[clang::lifetimebound(42)]]); // expected-error {{takes no arguments}}
-
-  void attr_on_ptr_arg(int * [[clang::lifetimebound]] ptr); // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-  static_assert((int [[clang::lifetimebound]]) 12); // expected-error {{cannot be applied to types}}
-  int* attr_on_unnamed_arg(const int& [[clang::lifetimebound]]); // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-  template <typename T>
-  int* attr_on_template_ptr_arg(T * [[clang::lifetimebound]] ptr); // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-
-  int (*func_ptr)(int) [[clang::lifetimebound]]; // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-  int (*(*func_ptr_ptr)(int) [[clang::lifetimebound]])(int); // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
-  struct X {};
-  int (X::*member_func_ptr)(int) [[clang::lifetimebound]]; // expected-error {{'lifetimebound' attribute only applies to parameters and implicit object parameters}}
 }
 
 namespace usage_ok {