[vxworks] make wint_t and wchar_t the same distinct type

We used to define WINT_TYPE to WCHAR_TYPE, so that both wint_t and
wchar_t mapped to the same underlying type, but this caused a glitch
in Wstringop-overflow-6.C: on vxworks, wint_t is typedef'ed to
wchar_t, headers got included in the test that declared functions that
take wint_t parameters, and those conflicted with the builtin
declarations that had wint_t mapped to the underlying integral type.

The problem is that, in C++, wchar_t is a distinct type.  Having
wint_t be a typedef to wchar_t in the headers, but a typedef to
wchar_t's underlying integral type in builtins, makes for mismatches
between the declarations.

This patch defines WINT_TYPE to "wchar_t" for vxworks, and adjusts the
fallout, namely:

- since wchar_t may not have been defined yet when
  c_common_nodes_and_builtins runs, use the node already reserved for
  wchar_t for wint_t when WINT_TYPE is defined to wchar_t.

- for the same reason, when WINT_TYPE is wchar_t and we're not
  compiling C++ where wchar_t is a compiler built-in, define
  __WINT_TYPE__ to WCHAR_TYPE rather than WINT_TYPE, because wchar_t
  may not even be defined in the translation unit.

- recognize and handle wchar_type_node when type_suffix is called for
  wint_type_node.


for  gcc/ChangeLog

	* config/vx-common.h (WINT_TYPE): Alias to "wchar_t".

for  gcc/c-family/ChangeLog

	* c-common.cc (c_common_nodes_and_builtins): Take
	wchar_type_node for wint_type_node when aliased.
	(c_stddef_cpp_builtins): Define __WINT_TYPE__, when aliased to
	wchar_t, to the underlying type rather than wchar_t in
	non-C++.
	* c-cppbuiltin.cc (type_suffix): Handle wchar_type_node.

3 files changed, 16 insertions, 4 deletions

diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index 0546821..bfb950e 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -4576,8 +4576,11 @@ c_common_nodes_and_builtins (void)
   char32_array_type_node
     = build_array_type (char32_type_node, array_domain_type);
 
-  wint_type_node =
-    TREE_TYPE (identifier_global_value (get_identifier (WINT_TYPE)));
+  if (strcmp (WINT_TYPE, "wchar_t") == 0)
+    wint_type_node = wchar_type_node;
+  else
+    wint_type_node =
+      TREE_TYPE (identifier_global_value (get_identifier (WINT_TYPE)));
 
   intmax_type_node =
     TREE_TYPE (identifier_global_value (get_identifier (INTMAX_TYPE)));
@@ -5359,7 +5362,14 @@ c_stddef_cpp_builtins(void)
   builtin_define_with_value ("__SIZE_TYPE__", SIZE_TYPE, 0);
   builtin_define_with_value ("__PTRDIFF_TYPE__", PTRDIFF_TYPE, 0);
   builtin_define_with_value ("__WCHAR_TYPE__", MODIFIED_WCHAR_TYPE, 0);
-  builtin_define_with_value ("__WINT_TYPE__", WINT_TYPE, 0);
+  /* C++ has wchar_t as a builtin type, C doesn't, so if WINT_TYPE
+     maps to wchar_t, define it to the underlying WCHAR_TYPE in C, and
+     to wchar_t in C++, so the desired type equivalence holds.  */
+  if (!c_dialect_cxx ()
+      && strcmp (WINT_TYPE, "wchar_t") == 0)
+    builtin_define_with_value ("__WINT_TYPE__", WCHAR_TYPE, 0);
+  else
+    builtin_define_with_value ("__WINT_TYPE__", WINT_TYPE, 0);
   builtin_define_with_value ("__INTMAX_TYPE__", INTMAX_TYPE, 0);
   builtin_define_with_value ("__UINTMAX_TYPE__", UINTMAX_TYPE, 0);
   if (flag_char8_t)
diff --git a/gcc/c-family/c-cppbuiltin.cc b/gcc/c-family/c-cppbuiltin.cc
index b333f97..98f5aef 100644
--- a/gcc/c-family/c-cppbuiltin.cc
+++ b/gcc/c-family/c-cppbuiltin.cc
@@ -1903,6 +1903,8 @@ type_suffix (tree type)
 	      systems use it anyway.  */
 	   || type == char_type_node)
     is_long = 0;
+  else if (type == wchar_type_node)
+    return type_suffix (underlying_wchar_type_node);
   else
     gcc_unreachable ();
 
diff --git a/gcc/config/vx-common.h b/gcc/config/vx-common.h
index 83580d0..9733c90 100644
--- a/gcc/config/vx-common.h
+++ b/gcc/config/vx-common.h
@@ -69,7 +69,7 @@ along with GCC; see the file COPYING3.  If not see
 #undef WINT_TYPE_SIZE
 #define WINT_TYPE_SIZE WCHAR_TYPE_SIZE
 #undef WINT_TYPE
-#define WINT_TYPE WCHAR_TYPE
+#define WINT_TYPE "wchar_t"
 
 /* ---------------------- Debug and unwind info formats ------------------  */