[PATCH v6 13/14] c++: Implement __rank built-in trait

[Ken Matsui <kmatsui@gcc.gnu.org>]

This patch implements built-in trait for std::rank.

gcc/cp/ChangeLog:

	* cp-trait.def: Define __rank.
	* semantics.cc (trait_expr_value): Handle CPTK_RANK.
	(finish_trait_expr): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/has-builtin-1.C: Test existence of __rank.
	* g++.dg/ext/rank.C: New test.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 gcc/cp/cp-trait.def                      |  1 +
 gcc/cp/semantics.cc                      | 23 ++++++++++++++++++++---
 gcc/testsuite/g++.dg/ext/has-builtin-1.C |  3 +++
 gcc/testsuite/g++.dg/ext/rank.C          | 24 ++++++++++++++++++++++++
 4 files changed, 48 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/ext/rank.C

diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index 11270f3ae6b..3d5a7970563 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -95,6 +95,7 @@ DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
 DEFTRAIT_EXPR (IS_TRIVIALLY_CONSTRUCTIBLE, "__is_trivially_constructible", -1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
 DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
+DEFTRAIT_EXPR (RANK, "__rank", 1)
 DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)
 DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY, "__reference_converts_from_temporary", 2)
 DEFTRAIT_TYPE (REMOVE_ALL_EXTENTS, "__remove_all_extents", 1)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 256e7ef8166..c3254784fc5 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12538,6 +12538,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_DEDUCIBLE:
       return type_targs_deducible_from (type1, type2);
 
+    /* __rank is handled in finish_trait_expr. */
+    case CPTK_RANK:
+
 #define DEFTRAIT_TYPE(CODE, NAME, ARITY) \
     case CPTK_##CODE:
 #include "cp-trait.def"
@@ -12610,7 +12613,10 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
   if (processing_template_decl)
     {
       tree trait_expr = make_node (TRAIT_EXPR);
-      TREE_TYPE (trait_expr) = boolean_type_node;
+      if (kind == CPTK_RANK)
+	TREE_TYPE (trait_expr) = size_type_node;
+      else
+	TREE_TYPE (trait_expr) = boolean_type_node;
       TRAIT_EXPR_TYPE1 (trait_expr) = type1;
       TRAIT_EXPR_TYPE2 (trait_expr) = type2;
       TRAIT_EXPR_KIND (trait_expr) = kind;
@@ -12698,6 +12704,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_SAME:
     case CPTK_IS_SCOPED_ENUM:
     case CPTK_IS_UNION:
+    case CPTK_RANK:
       break;
 
     case CPTK_IS_LAYOUT_COMPATIBLE:
@@ -12729,8 +12736,18 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
       gcc_unreachable ();
     }
 
-  tree val = (trait_expr_value (kind, type1, type2)
-	      ? boolean_true_node : boolean_false_node);
+  tree val;
+  if (kind == CPTK_RANK)
+    {
+      size_t rank = 0;
+      for (; TREE_CODE (type1) == ARRAY_TYPE; type1 = TREE_TYPE (type1))
+	++rank;
+      val = build_int_cst (size_type_node, rank);
+    }
+  else
+    val = (trait_expr_value (kind, type1, type2)
+	   ? boolean_true_node : boolean_false_node);
+
   return maybe_wrap_with_location (val, loc);
 }
 
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index 5b590db1cf6..a00193c1a81 100644
--- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
+++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
@@ -167,6 +167,9 @@
 #if !__has_builtin (__is_union)
 # error "__has_builtin (__is_union) failed"
 #endif
+#if !__has_builtin (__rank)
+# error "__has_builtin (__rank) failed"
+#endif
 #if !__has_builtin (__reference_constructs_from_temporary)
 # error "__has_builtin (__reference_constructs_from_temporary) failed"
 #endif
diff --git a/gcc/testsuite/g++.dg/ext/rank.C b/gcc/testsuite/g++.dg/ext/rank.C
new file mode 100644
index 00000000000..28894184387
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/rank.C
@@ -0,0 +1,24 @@
+// { dg-do compile { target c++11 } }
+
+#include <cstddef>
+
+#define SA(X) static_assert((X),#X)
+
+class ClassType { };
+
+SA(__rank(int) == 0);
+SA(__rank(int[2]) == 1);
+SA(__rank(int[][4]) == 2);
+SA(__rank(int[2][2][4][4][6][6]) == 6);
+SA(__rank(ClassType) == 0);
+SA(__rank(ClassType[2]) == 1);
+SA(__rank(ClassType[][4]) == 2);
+SA(__rank(ClassType[2][2][4][4][6][6]) == 6);
+
+template<class T> void f(T) = delete;
+void f(size_t);
+
+template<class T>
+void g() { f(__rank(T)); }
+
+template void g<int>();
-- 
2.43.2