Implement P0482R5, char8_t: A type for UTF-8 characters and strings

gcc/cp/
	* cvt.c (type_promotes_to): Handle char8_t promotion.
	* decl.c (grokdeclarator): Handle invalid type specifier
	combinations involving char8_t.
	* lex.c (init_reswords): Add char8_t as a reserved word.
	* mangle.c (write_builtin_type): Add name mangling for char8_t (Du).
	* parser.c (cp_keyword_starts_decl_specifier_p)
	(cp_parser_simple_type_specifier): Recognize char8_t as a simple
	type specifier.
	(cp_parser_string_literal): Use char8_array_type_node for the type
	of CPP_UTF8STRING.
	(cp_parser_set_decl_spec_type): Tolerate char8_t typedefs in system
	headers.
	* rtti.c (emit_support_tinfos): type_info support for char8_t.
	* tree.c (char_type_p): Recognize char8_t as a character type.
	* typeck.c (string_conv_p): Handle conversions of u8 string
	literals of char8_t type.
	(check_literal_operator_args): Handle UDLs with u8 string literals
	of char8_t type.
	* typeck2.c (ordinary_char_type_p): New.
	(digest_init_r): Disallow initializing a char array with a u8 string
	literal.
gcc/c-family/
	* c-common.c (c_common_reswords): Add char8_t.
	(fix_string_type): Use char8_t for the type of u8 string literals.
	(c_common_get_alias_set): char8_t doesn't alias.
	(c_common_nodes_and_builtins): Define char8_t as a builtin type in
	C++.
	(c_stddef_cpp_builtins): Add __CHAR8_TYPE__.
	(keyword_begins_type_specifier): Add RID_CHAR8.
	* c-common.h (rid): Add RID_CHAR8.
	(c_tree_index): Add CTI_CHAR8_TYPE and CTI_CHAR8_ARRAY_TYPE.
	Define D_CXX_CHAR8_T and D_CXX_CHAR8_T_FLAGS.
	Define char8_type_node and char8_array_type_node.
	* c-cppbuiltin.c (cpp_atomic_builtins): Predefine
	__GCC_ATOMIC_CHAR8_T_LOCK_FREE.
	(c_cpp_builtins): Predefine __cpp_char8_t.
	* c-lex.c (lex_string): Use char8_array_type_node as the type of
	CPP_UTF8STRING.
	(lex_charconst): Use char8_type_node as the type of CPP_UTF8CHAR.
	* c-opts.c: If not otherwise specified, enable -fchar8_t when
	targeting C++2a.
	* c.opt: Add the -fchar8_t command line option.
libiberty/
	* cp-demangle.c (cplus_demangle_builtin_types)
	(cplus_demangle_type): Add name demangling for char8_t (Du).
	* cp-demangle.h: Increase D_BUILTIN_TYPE_COUNT to accommodate the
	new char8_t type.

From-SVN: r267923

1 files changed, 39 insertions, 2 deletions

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index d2ea384..2a5a8e7 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -79,6 +79,7 @@ machine_mode c_default_pointer_mode = VOIDmode;
 	tree signed_char_type_node;
 	tree wchar_type_node;
 
+	tree char8_type_node;
 	tree char16_type_node;
 	tree char32_type_node;
 
@@ -128,6 +129,11 @@ machine_mode c_default_pointer_mode = VOIDmode;
 
 	tree wchar_array_type_node;
 
+   Type `char8_t[SOMENUMBER]' or something like it.
+   Used when a UTF-8 string literal is created.
+
+	tree char8_array_type_node;
+
    Type `char16_t[SOMENUMBER]' or something like it.
    Used when a UTF-16 string literal is created.
 
@@ -452,6 +458,7 @@ const struct c_common_resword c_common_reswords[] =
   { "case",		RID_CASE,	0 },
   { "catch",		RID_CATCH,	D_CXX_OBJC | D_CXXWARN },
   { "char",		RID_CHAR,	0 },
+  { "char8_t",		RID_CHAR8,	D_CXX_CHAR8_T_FLAGS | D_CXXWARN },
   { "char16_t",		RID_CHAR16,	D_CXXONLY | D_CXX11 | D_CXXWARN },
   { "char32_t",		RID_CHAR32,	D_CXXONLY | D_CXX11 | D_CXXWARN },
   { "class",		RID_CLASS,	D_CXX_OBJC | D_CXXWARN },
@@ -748,6 +755,11 @@ fix_string_type (tree value)
       charsz = 1;
       e_type = char_type_node;
     }
+  else if (flag_char8_t && TREE_TYPE (value) == char8_array_type_node)
+    {
+      charsz = TYPE_PRECISION (char8_type_node) / BITS_PER_UNIT;
+      e_type = char8_type_node;
+    }
   else if (TREE_TYPE (value) == char16_array_type_node)
     {
       charsz = TYPE_PRECISION (char16_type_node) / BITS_PER_UNIT;
@@ -828,7 +840,8 @@ fix_string_type (tree value)
    CPP_STRING16, or CPP_STRING32.  Return CPP_OTHER in case of error.
    This may not be exactly the string token type that initially created
    the string, since CPP_WSTRING is indistinguishable from the 16/32 bit
-   string type at this point.
+   string type, and CPP_UTF8STRING is indistinguishable from CPP_STRING
+   at this point.
 
    This effectively reverses part of the logic in lex_string and
    fix_string_type.  */
@@ -3640,8 +3653,12 @@ c_common_get_alias_set (tree t)
   if (!TYPE_P (t))
     return -1;
 
+  /* Unlike char, char8_t doesn't alias. */
+  if (flag_char8_t && t == char8_type_node)
+    return -1;
+
   /* The C standard guarantees that any object may be accessed via an
-     lvalue that has character type.  */
+     lvalue that has narrow character type (except char8_t).  */
   if (t == char_type_node
       || t == signed_char_type_node
       || t == unsigned_char_type_node)
@@ -4050,6 +4067,7 @@ c_get_ident (const char *id)
 void
 c_common_nodes_and_builtins (void)
 {
+  int char8_type_size;
   int char16_type_size;
   int char32_type_size;
   int wchar_type_size;
@@ -4341,6 +4359,22 @@ c_common_nodes_and_builtins (void)
   wchar_array_type_node
     = build_array_type (wchar_type_node, array_domain_type);
 
+  /* Define 'char8_t'.  */
+  char8_type_node = get_identifier (CHAR8_TYPE);
+  char8_type_node = TREE_TYPE (identifier_global_value (char8_type_node));
+  char8_type_size = TYPE_PRECISION (char8_type_node);
+  if (c_dialect_cxx ())
+    {
+      char8_type_node = make_unsigned_type (char8_type_size);
+
+      if (flag_char8_t)
+        record_builtin_type (RID_CHAR8, "char8_t", char8_type_node);
+    }
+
+  /* This is for UTF-8 string constants.  */
+  char8_array_type_node
+    = build_array_type (char8_type_node, array_domain_type);
+
   /* Define 'char16_t'.  */
   char16_type_node = get_identifier (CHAR16_TYPE);
   char16_type_node = TREE_TYPE (identifier_global_value (char16_type_node));
@@ -5138,6 +5172,8 @@ c_stddef_cpp_builtins(void)
   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)
+    builtin_define_with_value ("__CHAR8_TYPE__", CHAR8_TYPE, 0);
   builtin_define_with_value ("__CHAR16_TYPE__", CHAR16_TYPE, 0);
   builtin_define_with_value ("__CHAR32_TYPE__", CHAR32_TYPE, 0);
   if (SIG_ATOMIC_TYPE)
@@ -7856,6 +7892,7 @@ keyword_begins_type_specifier (enum rid keyword)
     case RID_ACCUM:
     case RID_BOOL:
     case RID_WCHAR:
+    case RID_CHAR8:
     case RID_CHAR16:
     case RID_CHAR32:
     case RID_SAT: