c++: implement __remove_cv, __remove_reference and __remove_cvref

This implements builtins for std::remove_cv, std::remove_reference and
std::remove_cvref using TRAIT_TYPE from the previous patch.

gcc/c-family/ChangeLog:

	* c-common.cc (c_common_reswords): Add __remove_cv,
	__remove_reference and __remove_cvref.
	* c-common.h (enum rid): Add RID_REMOVE_CV, RID_REMOVE_REFERENCE
	and RID_REMOVE_CVREF.

gcc/cp/ChangeLog:

	* constraint.cc (diagnose_trait_expr): Handle CPTK_REMOVE_CV,
	CPTK_REMOVE_REFERENCE and CPTK_REMOVE_CVREF.
	* cp-objcp-common.cc (names_builtin_p): Likewise.
	* cp-tree.h (enum cp_trait_kind): Add CPTK_REMOVE_CV,
	CPTK_REMOVE_REFERENCE and CPTK_REMOVE_CVREF.
	* cxx-pretty-print.cc (pp_cxx_trait): Handle CPTK_REMOVE_CV,
	CPTK_REMOVE_REFERENCE and CPTK_REMOVE_CVREF.
	* parser.cc (cp_keyword_starts_decl_specifier_p): Return true
	for RID_REMOVE_CV, RID_REMOVE_REFERENCE and RID_REMOVE_CVREF.
	(cp_parser_trait): Handle RID_REMOVE_CV, RID_REMOVE_REFERENCE
	and RID_REMOVE_CVREF.
	(cp_parser_simple_type_specifier): Likewise.
	* semantics.cc (finish_trait_type): Likewise.

libstdc++-v3/ChangeLog:

	* include/bits/unique_ptr.h (unique_ptr<_Tp[], _Dp>): Remove
	__remove_cv and use __remove_cv_t instead.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/has-builtin-1.C: Test existence of __remove_cv,
	__remove_reference and __remove_cvref.
	* g++.dg/ext/remove_cv.C: New test.
	* g++.dg/ext/remove_reference.C: New test.
	* g++.dg/ext/remove_cvref.C: New test.

6 files changed, 47 insertions, 1 deletions

diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 266ec58..ca73aff 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3714,6 +3714,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_BASES:
     case CPTK_DIRECT_BASES:
     case CPTK_UNDERLYING_TYPE:
+    case CPTK_REMOVE_CV:
+    case CPTK_REMOVE_REFERENCE:
+    case CPTK_REMOVE_CVREF:
       /* We shouldn't see these non-expression traits.  */
       gcc_unreachable ();
     /* We deliberately omit the default case so that when adding a new
diff --git a/gcc/cp/cp-objcp-common.cc b/gcc/cp/cp-objcp-common.cc
index 380f288..2d3f206 100644
--- a/gcc/cp/cp-objcp-common.cc
+++ b/gcc/cp/cp-objcp-common.cc
@@ -467,6 +467,9 @@ names_builtin_p (const char *name)
     case RID_IS_NOTHROW_CONVERTIBLE:
     case RID_REF_CONSTRUCTS_FROM_TEMPORARY:
     case RID_REF_CONVERTS_FROM_TEMPORARY:
+    case RID_REMOVE_CV:
+    case RID_REMOVE_REFERENCE:
+    case RID_REMOVE_CVREF:
       return true;
     default:
       break;
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index ff9913c..3cbcdf7 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -1412,7 +1412,10 @@ enum cp_trait_kind
   CPTK_IS_CONVERTIBLE,
   CPTK_IS_NOTHROW_CONVERTIBLE,
   CPTK_REF_CONSTRUCTS_FROM_TEMPORARY,
-  CPTK_REF_CONVERTS_FROM_TEMPORARY
+  CPTK_REF_CONVERTS_FROM_TEMPORARY,
+  CPTK_REMOVE_CV,
+  CPTK_REMOVE_REFERENCE,
+  CPTK_REMOVE_CVREF,
 };
 
 /* The types that we are processing.  */
diff --git a/gcc/cp/cxx-pretty-print.cc b/gcc/cp/cxx-pretty-print.cc
index 752ce3f..b916154 100644
--- a/gcc/cp/cxx-pretty-print.cc
+++ b/gcc/cp/cxx-pretty-print.cc
@@ -2728,6 +2728,15 @@ pp_cxx_trait (cxx_pretty_printer *pp, tree t)
     case CPTK_UNDERLYING_TYPE:
       pp_cxx_ws_string (pp, "__underlying_type");
       break;
+    case CPTK_REMOVE_CV:
+      pp_cxx_ws_string (pp, "__remove_cv");
+      break;
+    case CPTK_REMOVE_REFERENCE:
+      pp_cxx_ws_string (pp, "__remove_reference");
+      break;
+    case CPTK_REMOVE_CVREF:
+      pp_cxx_ws_string (pp, "__remove_cvref");
+      break;
     default:
       gcc_unreachable ();
     }
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 9f5e2c2..d592d78 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -1147,6 +1147,9 @@ cp_keyword_starts_decl_specifier_p (enum rid keyword)
       /* C++11 extensions.  */
     case RID_DECLTYPE:
     case RID_UNDERLYING_TYPE:
+    case RID_REMOVE_CV:
+    case RID_REMOVE_REFERENCE:
+    case RID_REMOVE_CVREF:
     case RID_CONSTEXPR:
       /* C++20 extensions.  */
     case RID_CONSTINIT:
@@ -11027,6 +11030,18 @@ cp_parser_trait (cp_parser* parser, enum rid keyword)
       kind = CPTK_REF_CONVERTS_FROM_TEMPORARY;
       binary = true;
       break;
+    case RID_REMOVE_CV:
+      kind = CPTK_REMOVE_CV;
+      type = true;
+      break;
+    case RID_REMOVE_REFERENCE:
+      kind = CPTK_REMOVE_REFERENCE;
+      type = true;
+      break;
+    case RID_REMOVE_CVREF:
+      kind = CPTK_REMOVE_CVREF;
+      type = true;
+      break;
     default:
       gcc_unreachable ();
     }
@@ -19867,6 +19882,9 @@ cp_parser_simple_type_specifier (cp_parser* parser,
       return type;
 
     case RID_UNDERLYING_TYPE:
+    case RID_REMOVE_CV:
+    case RID_REMOVE_REFERENCE:
+    case RID_REMOVE_CVREF:
       type = cp_parser_trait (parser, token->keyword);
       if (decl_specs)
 	cp_parser_set_decl_spec_type (decl_specs, type,
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index aae492d..66ee218 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12240,6 +12240,16 @@ finish_trait_type (cp_trait_kind kind, tree type1, tree type2)
     {
     case CPTK_UNDERLYING_TYPE:
       return finish_underlying_type (type1);
+    case CPTK_REMOVE_CV:
+      return cv_unqualified (type1);
+    case CPTK_REMOVE_REFERENCE:
+      if (TYPE_REF_P (type1))
+	type1 = TREE_TYPE (type1);
+      return type1;
+    case CPTK_REMOVE_CVREF:
+      if (TYPE_REF_P (type1))
+	type1 = TREE_TYPE (type1);
+      return cv_unqualified (type1);
     default:
       gcc_unreachable ();
     }