Remove the fix for attributes in non-type template parameters.

The C++ standard is not clear whether attributes are permitted in the
declarations of non-type template parameters. Previous commits added
code to recognize and instantiate attributes in these contexts, but
concerns were raised that more changes might be needed. This change
removes the previously added support pending clarification from WG21.
See also P3324 (Attributes for namespace aliases, template parameters,
and lambda captures).

Author: tahonermann

clang/lib/Sema/SemaTemplate.cpp

@@ -1550,8 +1550,6 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
     IdResolver.AddDecl(Param);
   }
 
-  ProcessDeclAttributes(S, Param, D);
-
   // C++0x [temp.param]p9:
   //   A default template-argument may be specified for any kind of
   //   template-parameter that is not a template parameter pack.

clang/test/SemaSYCL/sycl-kernel-entry-point-attr-appertainment.cpp

@@ -226,7 +226,11 @@ int bad16();
 void bad17(void (fp [[clang::sycl_kernel_entry_point(BADKN<17>)]])());
 
 // Function template parameters.
-// expected-error@+1 {{'sycl_kernel_entry_point' attribute only applies to functions}}
+// FIXME: Clang currently ignores attributes that appear in template parameters
+// FIXME: and the C++ standard is unclear regarding whether such attributes are
+// FIXME: permitted. P3324 (Attributes for namespace aliases, template
+// FIXME: parameters, and lambda captures) seeks to clarify the situation.
+// FIXME-expected-error@+1 {{'sycl_kernel_entry_point' attribute only applies to functions}}
 template<void (fp [[clang::sycl_kernel_entry_point(BADKN<18>)]])()>
 void bad18();