[APINotes] Upstream Sema logic to apply API Notes to decls

This upstreams more of the Clang API Notes functionality that is currently implemented in the Apple fork: https://github.com/apple/llvm-project/tree/next/clang/lib/APINotes

Author: egorzhdan

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -10723,6 +10723,13 @@ def warn_imp_cast_drops_unaligned : Warning<
 
 } // end of sema category
 
+let CategoryName = "API Notes Issue" in {
+
+def err_incompatible_replacement_type : Error<
+  "API notes replacement type %0 has a different size from original type %1">;
+
+} // end of API Notes category
+
 let CategoryName = "OpenMP Issue" in {
 // OpenMP support.
 def err_omp_expected_var_arg : Error<

clang/include/clang/Sema/Sema.h

@@ -4763,6 +4763,12 @@ class Sema final {
   bool checkCommonAttributeFeatures(const Stmt *S, const ParsedAttr &A,
                                     bool SkipArgCountCheck = false);
 
+  /// Map any API notes provided for this declaration to attributes on the
+  /// declaration.
+  ///
+  /// Triggered by declaration-attribute processing.
+  void ProcessAPINotes(Decl *D);
+
   /// Determine if type T is a valid subject for a nonnull and similar
   /// attributes. By default, we look through references (the behavior used by
   /// nonnull), but if the second parameter is true, then we treat a reference

clang/lib/Sema/CMakeLists.txt

@@ -27,6 +27,7 @@ add_clang_library(clangSema
   Sema.cpp
   SemaAccess.cpp
   SemaAttr.cpp
+  SemaAPINotes.cpp
   SemaAvailability.cpp
   SemaCXXScopeSpec.cpp
   SemaCast.cpp