Merge from trunk revision f35be1268c996d993ab0b4ff329734d467474445.

15 files changed, 409 insertions, 74 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 9e5f83c..ba3d76d 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,143 @@
+2022-09-15  Richard Biener  <rguenther@suse.de>
+
+	* c-common.h (build_void_list_node): Remove.
+	* c-common.cc (c_common_nodes_and_builtins): Do not initialize
+	void_list_node.
+
+2022-09-09  Jan-Benedict Glaw  <jbglaw@lug-owl.de>
+
+	* c-format.cc (convert_format_name_to_system_name): Fix warning.
+
+2022-09-07  Joseph Myers  <joseph@codesourcery.com>
+
+	* c-common.cc (c_common_reswords): Use D_C2X instead of D_CXXONLY
+	for alignas, alignof, bool, false, static_assert, thread_local and
+	true.
+
+2022-09-07  Jakub Jelinek  <jakub@redhat.com>
+
+	* c.opt (Winvalid-utf8): Use ObjC instead of objC.  Remove
+	" in comments" from description.
+	(Wunicode): New option.
+
+2022-09-06  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/106836
+	* c-omp.cc (c_omp_split_clauses): Handle OMP_CLAUSE_DOACROSS.
+
+2022-09-03  Jakub Jelinek  <jakub@redhat.com>
+
+	* c-pragma.h (enum pragma_omp_clause): Add PRAGMA_OMP_CLAUSE_DOACROSS.
+	* c-omp.cc (c_finish_omp_depobj): Check also for OMP_CLAUSE_DOACROSS
+	clause and diagnose it.  Don't handle OMP_CLAUSE_DEPEND_SOURCE and
+	OMP_CLAUSE_DEPEND_SINK.  Assert kind is not OMP_CLAUSE_DEPEND_INVALID.
+
+2022-09-02  David Malcolm  <dmalcolm@redhat.com>
+
+	PR c/90885
+	* c-common.h (check_for_xor_used_as_pow): New decl.
+	* c-lex.cc (c_lex_with_flags): Add DECIMAL_INT to flags as appropriate.
+	* c-warn.cc (check_for_xor_used_as_pow): New.
+	* c.opt (Wxor-used-as-pow): New.
+
+2022-09-01  Jason Merrill  <jason@redhat.com>
+
+	* c-common.cc (c_common_nodes_and_builtins): Set TREE_STRING_FLAG on
+	char8_t.
+	(braced_list_to_string): Check for char-sized elements.
+
+2022-09-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/106655
+	* c.opt (-Winvalid-utf8): New warning.
+	* c-opts.cc (c_common_handle_option) <case OPT_finput_charset_>:
+	Set cpp_opts->cpp_input_charset_explicit.
+	(c_common_post_options): If -finput-charset=UTF-8 is explicit
+	in C++23, enable -Winvalid-utf8 by default and if -pedantic
+	or -pedantic-errors, make it a pedwarn.
+
+2022-08-31  Joseph Myers  <joseph@codesourcery.com>
+
+	* c-attribs.cc (handle_deprecated_attribute): Check and pedwarn
+	for LABEL_DECL.
+	* c-common.cc (c_add_case_label): Add argument ATTRS.  Call
+	decl_attributes.
+	* c-common.h (do_case, c_add_case_label): Update declarations.
+	* c-lex.cc (c_common_has_attribute): For C, produce a result of
+	201910 for fallthrough and 202106 for maybe_unused.
+
+2022-08-26  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/81159
+	* c.opt (Wself-move): New option.
+
+2022-08-26  Jakub Jelinek  <jakub@redhat.com>
+
+	* c-common.cc (check_builtin_function_arguments): Handle
+	BUILT_IN_ISSIGNALING.
+
+2022-08-26  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/106648
+	* c-cppbuiltin.cc (c_cpp_builtins): Predefine
+	__cpp_named_character_escapes to 202207L.
+
+2022-08-25  Marek Polacek  <polacek@redhat.com>
+
+	* c-common.cc (c_common_reswords): Enable nullptr in C2X.
+	(c_common_nodes_and_builtins): Create the built-in node for nullptr.
+	* c-common.h (enum c_tree_index): Add CTI_NULLPTR, CTI_NULLPTR_TYPE.
+	(struct c_common_resword): Resize the disable member.
+	(D_C2X): Add.
+	(nullptr_node): Define.
+	(nullptr_type_node): Define.
+	(NULLPTR_TYPE_P): Define.
+	* c-pretty-print.cc (c_pretty_printer::simple_type_specifier): Handle
+	NULLPTR_TYPE.
+	(c_pretty_printer::direct_abstract_declarator): Likewise.
+	(c_pretty_printer::constant): Likewise.
+
+2022-08-16  Tom Honermann  <tom@honermann.net>
+
+	PR c++/106423
+	* c-opts.cc (c_common_post_options): Disable -Wc++20-compat
+	diagnostics in C++20 and later.
+	* c.opt (Wc++20-compat): Enable hooks for the preprocessor.
+
+2022-08-11  Marek Polacek  <polacek@redhat.com>
+
+	PR middle-end/102633
+	* c-gimplify.cc (c_gimplify_expr) <case DECL_EXPR>: Don't call
+	suppress_warning here.
+
+2022-08-08  Tom Honermann  <tom@honermann.net>
+
+	PR preprocessor/106426
+	* c-opts.cc (c_common_post_options): Assign cpp_opts->unsigned_utf8char
+	subject to -fchar8_t, -fsigned-char, and/or -funsigned-char.
+
+2022-08-08  Tom Honermann  <tom@honermann.net>
+
+	* c-lex.cc (lex_string, lex_charconst): Use char8_t as the type
+	of CPP_UTF8CHAR and CPP_UTF8STRING when char8_t support is
+	enabled.
+	* c-opts.cc (c_common_post_options): Set flag_char8_t if
+	targeting C2x.
+
+2022-07-31  Lewis Hyatt  <lhyatt@gmail.com>
+
+	PR c++/66290
+	* c-common.h: Rename global done_lexing to
+	override_libcpp_locations.
+	* c-common.cc (c_cpp_diagnostic): Likewise.
+	* c-opts.cc (c_common_finish): Set override_libcpp_locations
+	(formerly done_lexing) immediately prior to calling cpp_finish ().
+
+2022-07-27  Lewis Hyatt  <lhyatt@gmail.com>
+
+	* c-ppoutput.cc (token_streamer::stream): Update input_location
+	prior to streaming each token.
+
 2022-07-23  Immad Mir  <mirimmad@outlook.com>
 
 	* c-attribs.cc: (c_common_attribute_table): add three new attributes
diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index e4f1d35..8bb80e2 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -4163,6 +4163,13 @@ handle_deprecated_attribute (tree *node, tree name,
 	  || TREE_CODE (decl) == CONST_DECL
 	  || objc_method_decl (TREE_CODE (decl)))
 	TREE_DEPRECATED (decl) = 1;
+      else if (TREE_CODE (decl) == LABEL_DECL)
+	{
+	  pedwarn (input_location, OPT_Wattributes, "%qE attribute ignored",
+		   name);
+	  *no_add_attrs = true;
+	  return NULL_TREE;
+	}
       else
 	warn = 1;
     }
diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index 655c3ae..c0f15f4 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -284,9 +284,11 @@ int c_inhibit_evaluation_warnings;
    be generated.  */
 bool in_late_binary_op;
 
-/* Whether lexing has been completed, so subsequent preprocessor
-   errors should use the compiler's input_location.  */
-bool done_lexing = false;
+/* Depending on which phase of processing we are in, we may need
+   to prefer input_location to libcpp's locations.  (Specifically,
+   after the C++ lexer is done lexing tokens, but prior to calling
+   cpp_finish (), we need to do so.  */
+bool override_libcpp_locations;
 
 /* Information about how a function name is generated.  */
 struct fname_var_t
@@ -322,8 +324,10 @@ static bool nonnull_check_p (tree, unsigned HOST_WIDE_INT);
    if they match the mask.
 
    Masks for languages:
-   C --std=c89: D_C99 | D_CXXONLY | D_OBJC | D_CXX_OBJC
-   C --std=c99: D_CXXONLY | D_OBJC
+   C --std=c89: D_C99 | D_C2X | D_CXXONLY | D_OBJC | D_CXX_OBJC
+   C --std=c99: D_C2X | D_CXXONLY | D_OBJC
+   C --std=c17: D_C2X | D_CXXONLY | D_OBJC
+   C --std=c2x: D_CXXONLY | D_OBJC
    ObjC is like C except that D_OBJC and D_CXX_OBJC are not set
    C++ --std=c++98: D_CONLY | D_CXX11 | D_CXX20 | D_OBJC
    C++ --std=c++11: D_CONLY | D_CXX20 | D_OBJC
@@ -455,11 +459,11 @@ const struct c_common_resword c_common_reswords[] =
   { "__GIMPLE",		RID_GIMPLE,	D_CONLY },
   { "__PHI",		RID_PHI,	D_CONLY },
   { "__RTL",		RID_RTL,	D_CONLY },
-  { "alignas",		RID_ALIGNAS,	D_CXXONLY | D_CXX11 | D_CXXWARN },
-  { "alignof",		RID_ALIGNOF,	D_CXXONLY | D_CXX11 | D_CXXWARN },
+  { "alignas",		RID_ALIGNAS,	D_C2X | D_CXX11 | D_CXXWARN },
+  { "alignof",		RID_ALIGNOF,	D_C2X | D_CXX11 | D_CXXWARN },
   { "asm",		RID_ASM,	D_ASM },
   { "auto",		RID_AUTO,	0 },
-  { "bool",		RID_BOOL,	D_CXXONLY | D_CXXWARN },
+  { "bool",		RID_BOOL,	D_C2X | D_CXXWARN },
   { "break",		RID_BREAK,	0 },
   { "case",		RID_CASE,	0 },
   { "catch",		RID_CATCH,	D_CXX_OBJC | D_CXXWARN },
@@ -485,7 +489,7 @@ const struct c_common_resword c_common_reswords[] =
   { "explicit",		RID_EXPLICIT,	D_CXXONLY | D_CXXWARN },
   { "export",		RID_EXPORT,	D_CXXONLY | D_CXXWARN },
   { "extern",		RID_EXTERN,	0 },
-  { "false",		RID_FALSE,	D_CXXONLY | D_CXXWARN },
+  { "false",		RID_FALSE,	D_C2X | D_CXXWARN },
   { "float",		RID_FLOAT,	0 },
   { "for",		RID_FOR,	0 },
   { "friend",		RID_FRIEND,	D_CXXONLY | D_CXXWARN },
@@ -498,7 +502,7 @@ const struct c_common_resword c_common_reswords[] =
   { "namespace",	RID_NAMESPACE,	D_CXXONLY | D_CXXWARN },
   { "new",		RID_NEW,	D_CXXONLY | D_CXXWARN },
   { "noexcept",		RID_NOEXCEPT,	D_CXXONLY | D_CXX11 | D_CXXWARN },
-  { "nullptr",		RID_NULLPTR,	D_CXXONLY | D_CXX11 | D_CXXWARN },
+  { "nullptr",		RID_NULLPTR,	D_C2X | D_CXX11 | D_CXXWARN },
   { "operator",		RID_OPERATOR,	D_CXXONLY | D_CXXWARN },
   { "private",		RID_PRIVATE,	D_CXX_OBJC | D_CXXWARN },
   { "protected",	RID_PROTECTED,	D_CXX_OBJC | D_CXXWARN },
@@ -511,15 +515,15 @@ const struct c_common_resword c_common_reswords[] =
   { "signed",		RID_SIGNED,	0 },
   { "sizeof",		RID_SIZEOF,	0 },
   { "static",		RID_STATIC,	0 },
-  { "static_assert",    RID_STATIC_ASSERT, D_CXXONLY | D_CXX11 | D_CXXWARN },
+  { "static_assert",    RID_STATIC_ASSERT, D_C2X | D_CXX11 | D_CXXWARN },
   { "static_cast",	RID_STATCAST,	D_CXXONLY | D_CXXWARN },
   { "struct",		RID_STRUCT,	0 },
   { "switch",		RID_SWITCH,	0 },
   { "template",		RID_TEMPLATE,	D_CXXONLY | D_CXXWARN },
   { "this",		RID_THIS,	D_CXXONLY | D_CXXWARN },
-  { "thread_local",	RID_THREAD,	D_CXXONLY | D_CXX11 | D_CXXWARN },
+  { "thread_local",	RID_THREAD,	D_C2X | D_CXX11 | D_CXXWARN },
   { "throw",		RID_THROW,	D_CXX_OBJC | D_CXXWARN },
-  { "true",		RID_TRUE,	D_CXXONLY | D_CXXWARN },
+  { "true",		RID_TRUE,	D_C2X | D_CXXWARN },
   { "try",		RID_TRY,	D_CXX_OBJC | D_CXXWARN },
   { "typedef",		RID_TYPEDEF,	0 },
   { "typename",		RID_TYPENAME,	D_CXXONLY | D_CXXWARN },
@@ -4501,8 +4505,6 @@ c_common_nodes_and_builtins (void)
     TYPE_NAME (void_type_node) = void_name;
   }
 
-  void_list_node = build_void_list_node ();
-
   /* Make a type to be the domain of a few array types
      whose domains don't really matter.
      200 is small enough that it always fits in size_t
@@ -4546,6 +4548,7 @@ c_common_nodes_and_builtins (void)
   if (c_dialect_cxx ())
     {
       char8_type_node = make_unsigned_type (char8_type_size);
+      TYPE_STRING_FLAG (char8_type_node) = true;
 
       if (flag_char8_t)
         record_builtin_type (RID_CHAR8, "char8_t", char8_type_node);
@@ -4721,6 +4724,18 @@ c_common_nodes_and_builtins (void)
   null_node = make_int_cst (1, 1);
   TREE_TYPE (null_node) = c_common_type_for_size (POINTER_SIZE, 0);
 
+  /* Create the built-in nullptr node.  This part of its initialization is
+     common to C and C++.  The front ends can further adjust its definition
+     in {c,cxx}_init_decl_processing.  In particular, we aren't setting the
+     alignment here for C++ backward ABI bug compatibility.  */
+  nullptr_type_node = make_node (NULLPTR_TYPE);
+  TYPE_SIZE (nullptr_type_node) = bitsize_int (GET_MODE_BITSIZE (ptr_mode));
+  TYPE_SIZE_UNIT (nullptr_type_node) = size_int (GET_MODE_SIZE (ptr_mode));
+  TYPE_UNSIGNED (nullptr_type_node) = 1;
+  TYPE_PRECISION (nullptr_type_node) = GET_MODE_BITSIZE (ptr_mode);
+  SET_TYPE_MODE (nullptr_type_node, ptr_mode);
+  nullptr_node = build_int_cst (nullptr_type_node, 0);
+
   /* Since builtin_types isn't gc'ed, don't export these nodes.  */
   memset (builtin_types, 0, sizeof (builtin_types));
 }
@@ -5052,11 +5067,12 @@ case_compare (splay_tree_key k1, splay_tree_key k2)
    CASES is a tree containing all the case ranges processed so far;
    COND is the condition for the switch-statement itself.
    Returns the CASE_LABEL_EXPR created, or ERROR_MARK_NODE if no
-   CASE_LABEL_EXPR is created.  */
+   CASE_LABEL_EXPR is created.  ATTRS are the attributes to be applied
+   to the label.  */
 
 tree
 c_add_case_label (location_t loc, splay_tree cases, tree cond,
-		  tree low_value, tree high_value)
+		  tree low_value, tree high_value, tree attrs)
 {
   tree type;
   tree label;
@@ -5065,6 +5081,7 @@ c_add_case_label (location_t loc, splay_tree cases, tree cond,
 
   /* Create the LABEL_DECL itself.  */
   label = create_artificial_label (loc);
+  decl_attributes (&label, attrs, 0);
 
   /* If there was an error processing the switch condition, bail now
      before we get more confused.  */
@@ -6292,6 +6309,7 @@ check_builtin_function_arguments (location_t loc, vec<location_t> arg_loc,
     case BUILT_IN_ISINF_SIGN:
     case BUILT_IN_ISNAN:
     case BUILT_IN_ISNORMAL:
+    case BUILT_IN_ISSIGNALING:
     case BUILT_IN_SIGNBIT:
       if (builtin_function_validate_nargs (loc, fndecl, nargs, 1))
 	{
@@ -6681,7 +6699,7 @@ c_cpp_diagnostic (cpp_reader *pfile ATTRIBUTE_UNUSED,
     default:
       gcc_unreachable ();
     }
-  if (done_lexing)
+  if (override_libcpp_locations)
     richloc->set_range (0, input_location, SHOW_RANGE_WITH_CARET);
   diagnostic_set_info_translated (&diagnostic, msg, ap,
 				  richloc, dlevel);
@@ -9326,12 +9344,15 @@ braced_list_to_string (tree type, tree ctor, bool member)
   if (!member && !tree_fits_uhwi_p (typesize))
     return ctor;
 
-  /* If the target char size differes from the host char size, we'd risk
+  /* If the target char size differs from the host char size, we'd risk
      loosing data and getting object sizes wrong by converting to
      host chars.  */
   if (TYPE_PRECISION (char_type_node) != CHAR_BIT)
     return ctor;
 
+  /* STRING_CST doesn't support wide characters.  */
+  gcc_checking_assert (TYPE_PRECISION (TREE_TYPE (type)) == CHAR_BIT);
+
   /* If the array has an explicit bound, use it to constrain the size
      of the string.  If it doesn't, be sure to create a string that's
      as long as implied by the index of the last zero specified via
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index f906439..2f592f5 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -375,6 +375,8 @@ enum c_tree_index
     CTI_DEFAULT_FUNCTION_TYPE,
 
     CTI_NULL,
+    CTI_NULLPTR,
+    CTI_NULLPTR_TYPE,
 
     /* These are not types, but we have to look them up all the time.  */
     CTI_FUNCTION_NAME_DECL,
@@ -409,7 +411,7 @@ struct c_common_resword
 {
   const char *const word;
   ENUM_BITFIELD(rid) const rid : 16;
-  const unsigned int disable   : 16;
+  const unsigned int disable   : 32;
 };
 
 /* Mode used to build pointers (VOIDmode means ptr_mode).  */
@@ -447,19 +449,20 @@ extern machine_mode c_default_pointer_mode;
 #define D_CONLY		0x0001	/* C only (not in C++).  */
 #define D_CXXONLY	0x0002	/* C++ only (not in C).  */
 #define D_C99		0x0004	/* In C, C99 only.  */
-#define D_CXX11         0x0008	/* In C++, C++11 only.  */
-#define D_EXT		0x0010	/* GCC extension.  */
-#define D_EXT89		0x0020	/* GCC extension incorporated in C99.  */
-#define D_ASM		0x0040	/* Disabled by -fno-asm.  */
-#define D_OBJC		0x0080	/* In Objective C and neither C nor C++.  */
-#define D_CXX_OBJC	0x0100	/* In Objective C, and C++, but not C.  */
-#define D_CXXWARN	0x0200	/* In C warn with -Wcxx-compat.  */
-#define D_CXX_CONCEPTS  0x0400	/* In C++, only with concepts.  */
-#define D_TRANSMEM	0X0800	/* C++ transactional memory TS.  */
-#define D_CXX_CHAR8_T	0X1000	/* In C++, only with -fchar8_t.  */
-#define D_CXX20		0x2000  /* In C++, C++20 only.  */
-#define D_CXX_COROUTINES 0x4000  /* In C++, only with coroutines.  */
-#define D_CXX_MODULES	0x8000  /* In C++, only with modules.  */
+#define D_C2X		0x0008	/* In C, C2X only.  */
+#define D_CXX11         0x0010	/* In C++, C++11 only.  */
+#define D_EXT		0x0020	/* GCC extension.  */
+#define D_EXT89		0x0040	/* GCC extension incorporated in C99.  */
+#define D_ASM		0x0080	/* Disabled by -fno-asm.  */
+#define D_OBJC		0x0100	/* In Objective C and neither C nor C++.  */
+#define D_CXX_OBJC	0x0200	/* In Objective C, and C++, but not C.  */
+#define D_CXXWARN	0x0400	/* In C warn with -Wcxx-compat.  */
+#define D_CXX_CONCEPTS  0x0800	/* In C++, only with concepts.  */
+#define D_TRANSMEM	0x1000	/* C++ transactional memory TS.  */
+#define D_CXX_CHAR8_T	0x2000	/* In C++, only with -fchar8_t.  */
+#define D_CXX20		0x4000  /* In C++, C++20 only.  */
+#define D_CXX_COROUTINES 0x8000  /* In C++, only with coroutines.  */
+#define D_CXX_MODULES	0x10000  /* In C++, only with modules.  */
 
 #define D_CXX_CONCEPTS_FLAGS D_CXXONLY | D_CXX_CONCEPTS
 #define D_CXX_CHAR8_T_FLAGS D_CXXONLY | D_CXX_CHAR8_T
@@ -534,6 +537,9 @@ extern const unsigned int num_c_common_reswords;
 
 /* The node for C++ `__null'.  */
 #define null_node                       c_global_trees[CTI_NULL]
+/* The nodes for `nullptr'.  */
+#define nullptr_node                    c_global_trees[CTI_NULLPTR]
+#define nullptr_type_node               c_global_trees[CTI_NULLPTR_TYPE]
 
 extern GTY(()) tree c_global_trees[CTI_MAX];
 
@@ -767,10 +773,12 @@ extern int max_tinst_depth;
 
 extern int c_inhibit_evaluation_warnings;
 
-/* Whether lexing has been completed, so subsequent preprocessor
-   errors should use the compiler's input_location.  */
+/* Depending on which phase of processing we are in, we may need
+   to prefer input_location to libcpp's locations.  (Specifically,
+   after the C++ lexer is done lexing tokens, but prior to calling
+   cpp_finish (), we need to do so.  */
 
-extern bool done_lexing;
+extern bool override_libcpp_locations;
 
 /* C types are partitioned into three subsets: object, function, and
    incomplete types.  */
@@ -845,7 +853,6 @@ extern tree identifier_global_tag (tree);
 extern bool names_builtin_p (const char *);
 extern tree c_linkage_bindings (tree);
 extern void record_builtin_type (enum rid, const char *, tree);
-extern tree build_void_list_node (void);
 extern void start_fname_decls (void);
 extern void finish_fname_decls (void);
 extern const char *fname_as_string (int);
@@ -1007,7 +1014,10 @@ extern void c_parse_final_cleanups (void);
 #define DECL_UNNAMED_BIT_FIELD(NODE) \
   (DECL_C_BIT_FIELD (NODE) && !DECL_NAME (NODE))
 
-extern tree do_case (location_t, tree, tree);
+/* True iff TYPE is cv decltype(nullptr).  */
+#define NULLPTR_TYPE_P(TYPE) (TREE_CODE (TYPE) == NULLPTR_TYPE)
+
+extern tree do_case (location_t, tree, tree, tree);
 extern tree build_stmt (location_t, enum tree_code, ...);
 extern tree build_real_imag_expr (location_t, enum tree_code, tree);
 
@@ -1035,7 +1045,8 @@ extern tree boolean_increment (enum tree_code, tree);
 
 extern int case_compare (splay_tree_key, splay_tree_key);
 
-extern tree c_add_case_label (location_t, splay_tree, tree, tree, tree);
+extern tree c_add_case_label (location_t, splay_tree, tree, tree, tree,
+			      tree = NULL_TREE);
 extern bool c_switch_covers_all_cases_p (splay_tree, tree);
 extern bool c_block_may_fallthru (const_tree);
 
@@ -1473,6 +1484,10 @@ extern tree do_warn_duplicated_branches_r (tree *, int *, void *);
 extern void warn_for_multistatement_macros (location_t, location_t,
 					    location_t, enum rid);
 
+extern void check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
+				       location_t operator_loc,
+				       tree rhs_val);
+
 /* In c-attribs.cc.  */
 extern bool attribute_takes_identifier_p (const_tree);
 extern tree handle_deprecated_attribute (tree *, tree, tree, int, bool *);
diff --git a/gcc/c-family/c-cppbuiltin.cc b/gcc/c-family/c-cppbuiltin.cc
index 4672ae8..a1557eb 100644
--- a/gcc/c-family/c-cppbuiltin.cc
+++ b/gcc/c-family/c-cppbuiltin.cc
@@ -1080,6 +1080,7 @@ c_cpp_builtins (cpp_reader *pfile)
 	  cpp_define (pfile, "__cpp_if_consteval=202106L");
 	  cpp_define (pfile, "__cpp_constexpr=202110L");
 	  cpp_define (pfile, "__cpp_multidimensional_subscript=202110L");
+	  cpp_define (pfile, "__cpp_named_character_escapes=202207L");
 	}
       if (flag_concepts)
         {
diff --git a/gcc/c-family/c-format.cc b/gcc/c-family/c-format.cc
index 68b94da..a6c380b 100644
--- a/gcc/c-family/c-format.cc
+++ b/gcc/c-family/c-format.cc
@@ -5111,8 +5111,7 @@ convert_format_name_to_system_name (const char *attr_name)
 
 #ifdef TARGET_OVERRIDES_FORMAT_ATTRIBUTES
   /* Check if format attribute is overridden by target.  */
-  if (TARGET_OVERRIDES_FORMAT_ATTRIBUTES != NULL
-      && TARGET_OVERRIDES_FORMAT_ATTRIBUTES_COUNT > 0)
+  if (TARGET_OVERRIDES_FORMAT_ATTRIBUTES_COUNT > 0)
     {
       for (i = 0; i < TARGET_OVERRIDES_FORMAT_ATTRIBUTES_COUNT; ++i)
         {
diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc
index a6f26c9..039a4b9 100644
--- a/gcc/c-family/c-gimplify.cc
+++ b/gcc/c-family/c-gimplify.cc
@@ -708,18 +708,6 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED,
 	break;
       }
 
-    case DECL_EXPR:
-      /* This is handled mostly by gimplify.cc, but we have to deal with
-	 not warning about int x = x; as it is a GCC extension to turn off
-	 this warning but only if warn_init_self is zero.  */
-      if (VAR_P (DECL_EXPR_DECL (*expr_p))
-	  && !DECL_EXTERNAL (DECL_EXPR_DECL (*expr_p))
-	  && !TREE_STATIC (DECL_EXPR_DECL (*expr_p))
-	  && (DECL_INITIAL (DECL_EXPR_DECL (*expr_p)) == DECL_EXPR_DECL (*expr_p))
-	  && !warn_init_self)
-	suppress_warning (DECL_EXPR_DECL (*expr_p), OPT_Winit_self);
-      break;
-
     case PREINCREMENT_EXPR:
     case PREDECREMENT_EXPR:
     case POSTINCREMENT_EXPR:
diff --git a/gcc/c-family/c-lex.cc b/gcc/c-family/c-lex.cc
index 8bfa4f4..110d029 100644
--- a/gcc/c-family/c-lex.cc
+++ b/gcc/c-family/c-lex.cc
@@ -381,12 +381,14 @@ c_common_has_attribute (cpp_reader *pfile, bool std_syntax)
 	    }
 	  else
 	    {
-	      if (is_attribute_p ("deprecated", attr_name)
-		  || is_attribute_p ("maybe_unused", attr_name)
-		  || is_attribute_p ("fallthrough", attr_name))
+	      if (is_attribute_p ("deprecated", attr_name))
 		result = 201904;
+	      else if (is_attribute_p ("fallthrough", attr_name))
+		result = 201910;
 	      else if (is_attribute_p ("nodiscard", attr_name))
 		result = 202003;
+	      else if (is_attribute_p ("maybe_unused", attr_name))
+		result = 202106;
 	    }
 	  if (result)
 	    attr_name = NULL_TREE;
@@ -509,7 +511,11 @@ c_lex_with_flags (tree *value, location_t *loc, unsigned char *cpp_flags,
 	    /* C++ uses '0' to mark virtual functions as pure.
 	       Set PURE_ZERO to pass this information to the C++ parser.  */
 	    if (tok->val.str.len == 1 && *tok->val.str.text == '0')
-	      add_flags = PURE_ZERO;
+	      add_flags = PURE_ZERO | DECIMAL_INT;
+	    else if ((flags & CPP_N_INTEGER) && (flags & CPP_N_DECIMAL))
+	      /* -Wxor-used-as-pow is only active for LHS of ^ expressed
+		 as a decimal integer. */
+	      add_flags = DECIMAL_INT;
 	    *value = interpret_integer (tok, flags, &overflow);
 	    break;
 
@@ -1352,7 +1358,14 @@ lex_string (const cpp_token *tok, tree *valp, bool objc_string, bool translate)
 	default:
 	case CPP_STRING:
 	case CPP_UTF8STRING:
-	  value = build_string (1, "");
+	  if (type == CPP_UTF8STRING && flag_char8_t)
+	    {
+	      value = build_string (TYPE_PRECISION (char8_type_node)
+				    / TYPE_PRECISION (char_type_node),
+				    "");  /* char8_t is 8 bits */
+	    }
+	  else
+	    value = build_string (1, "");
 	  break;
 	case CPP_STRING16:
 	  value = build_string (TYPE_PRECISION (char16_type_node)
@@ -1425,9 +1438,7 @@ lex_charconst (const cpp_token *token)
     type = char16_type_node;
   else if (token->type == CPP_UTF8CHAR)
     {
-      if (!c_dialect_cxx ())
-	type = unsigned_char_type_node;
-      else if (flag_char8_t)
+      if (flag_char8_t)
         type = char8_type_node;
       else
         type = char_type_node;
diff --git a/gcc/c-family/c-omp.cc b/gcc/c-family/c-omp.cc
index 66d17a2..1b086d8 100644
--- a/gcc/c-family/c-omp.cc
+++ b/gcc/c-family/c-omp.cc
@@ -714,8 +714,17 @@ c_finish_omp_depobj (location_t loc, tree depobj,
 
   if (clause)
     {
-      gcc_assert (TREE_CODE (clause) == OMP_CLAUSE
-		  && OMP_CLAUSE_CODE (clause) == OMP_CLAUSE_DEPEND);
+      gcc_assert (TREE_CODE (clause) == OMP_CLAUSE);
+      if (OMP_CLAUSE_CODE (clause) == OMP_CLAUSE_DOACROSS)
+	{
+	  error_at (OMP_CLAUSE_LOCATION (clause),
+		    "%<depend(%s)%> is only allowed in %<omp ordered%>",
+		    OMP_CLAUSE_DOACROSS_KIND (clause)
+		    == OMP_CLAUSE_DOACROSS_SOURCE
+		    ? "source" : "sink");
+	  return;
+	}
+      gcc_assert (OMP_CLAUSE_CODE (clause) == OMP_CLAUSE_DEPEND);
       if (OMP_CLAUSE_CHAIN (clause))
 	error_at (OMP_CLAUSE_LOCATION (clause),
 		  "more than one locator in %<depend%> clause on %<depobj%> "
@@ -727,13 +736,6 @@ c_finish_omp_depobj (location_t loc, tree depobj,
 		    "%<depobj%> dependence type specified in %<depend%> "
 		    "clause on %<depobj%> construct");
 	  return;
-	case OMP_CLAUSE_DEPEND_SOURCE:
-	case OMP_CLAUSE_DEPEND_SINK:
-	  error_at (OMP_CLAUSE_LOCATION (clause),
-		    "%<depend(%s)%> is only allowed in %<omp ordered%>",
-		    OMP_CLAUSE_DEPEND_KIND (clause) == OMP_CLAUSE_DEPEND_SOURCE
-		    ? "source" : "sink");
-	  return;
 	case OMP_CLAUSE_DEPEND_IN:
 	case OMP_CLAUSE_DEPEND_OUT:
 	case OMP_CLAUSE_DEPEND_INOUT:
@@ -765,7 +767,7 @@ c_finish_omp_depobj (location_t loc, tree depobj,
 	}
     }
   else
-    gcc_assert (kind != OMP_CLAUSE_DEPEND_SOURCE);
+    gcc_assert (kind != OMP_CLAUSE_DEPEND_INVALID);
 
   if (depobj == error_mark_node)
     return;
@@ -1875,6 +1877,12 @@ c_omp_split_clauses (location_t loc, enum tree_code code,
 	case OMP_CLAUSE_DEPEND:
 	  s = C_OMP_CLAUSE_SPLIT_TARGET;
 	  break;
+	case OMP_CLAUSE_DOACROSS:
+	  /* This can happen with invalid depend(source) or
+	     depend(sink:vec) on target combined with other constructs.  */
+	  gcc_assert (OMP_CLAUSE_DOACROSS_DEPEND (clauses));
+	  s = C_OMP_CLAUSE_SPLIT_TARGET;
+	  break;
 	case OMP_CLAUSE_NUM_TEAMS:
 	  s = C_OMP_CLAUSE_SPLIT_TEAMS;
 	  break;
diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc
index b9f01a6..babaa2f 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -534,6 +534,7 @@ c_common_handle_option (size_t scode, const char *arg, HOST_WIDE_INT value,
 
     case OPT_finput_charset_:
       cpp_opts->input_charset = arg;
+      cpp_opts->cpp_input_charset_explicit = 1;
       break;
 
     case OPT_ftemplate_depth_:
@@ -1046,6 +1047,13 @@ c_common_post_options (const char **pfilename)
   else if (warn_narrowing == -1)
     warn_narrowing = 0;
 
+  if (cxx_dialect >= cxx20)
+    {
+      /* Don't warn about C++20 compatibility changes in C++20 or later.  */
+      warn_cxx20_compat = 0;
+      cpp_opts->cpp_warn_cxx20_compat = 0;
+    }
+
   /* C++17 has stricter evaluation order requirements; let's use some of them
      for earlier C++ as well, so chaining works as expected.  */
   if (c_dialect_cxx ()
@@ -1059,9 +1067,10 @@ c_common_post_options (const char **pfilename)
   if (flag_sized_deallocation == -1)
     flag_sized_deallocation = (cxx_dialect >= cxx14);
 
-  /* char8_t support is new in C++20.  */
+  /* char8_t support is implicitly enabled in C++20 and C2X.  */
   if (flag_char8_t == -1)
-    flag_char8_t = (cxx_dialect >= cxx20);
+    flag_char8_t = (cxx_dialect >= cxx20) || flag_isoc2x;
+  cpp_opts->unsigned_utf8char = flag_char8_t ? 1 : cpp_opts->unsigned_char;
 
   if (flag_extern_tls_init)
     {
@@ -1144,6 +1153,17 @@ c_common_post_options (const char **pfilename)
     lang_hooks.preprocess_options (parse_in);
   cpp_post_options (parse_in);
   init_global_opts_from_cpp (&global_options, cpp_get_options (parse_in));
+  /* For C++23 and explicit -finput-charset=UTF-8, turn on -Winvalid-utf8
+     by default and make it a pedwarn unless -Wno-invalid-utf8.  */
+  if (cxx_dialect >= cxx23
+      && cpp_opts->cpp_input_charset_explicit
+      && strcmp (cpp_opts->input_charset, "UTF-8") == 0
+      && (cpp_opts->cpp_warn_invalid_utf8
+	  || !global_options_set.x_warn_invalid_utf8))
+    {
+      global_options.x_warn_invalid_utf8 = 1;
+      cpp_opts->cpp_warn_invalid_utf8 = cpp_opts->cpp_pedantic ? 2 : 1;
+    }
 
   /* Let diagnostics infrastructure know how to convert input files the same
      way libcpp will do it, namely using the configured input charset and
@@ -1281,6 +1301,12 @@ c_common_finish (void)
 	}
     }
 
+  /* When we call cpp_finish (), it may generate some diagnostics using
+     locations it remembered from the preprocessing phase, e.g. for
+     -Wunused-macros.  So inform c_cpp_diagnostic () not to override those
+     locations with input_location, which would be incorrect now.  */
+  override_libcpp_locations = false;
+
   /* For performance, avoid tearing down cpplib's internal structures
      with cpp_destroy ().  */
   cpp_finish (parse_in, deps_stream);
diff --git a/gcc/c-family/c-ppoutput.cc b/gcc/c-family/c-ppoutput.cc
index cd38c96..98081cc 100644
--- a/gcc/c-family/c-ppoutput.cc
+++ b/gcc/c-family/c-ppoutput.cc
@@ -210,6 +210,10 @@ void
 token_streamer::stream (cpp_reader *pfile, const cpp_token *token,
 			location_t loc)
 {
+  /* Keep input_location up to date, since it is needed for processing early
+     pragmas such as #pragma GCC diagnostic.  */
+  input_location = loc;
+
   if (token->type == CPP_PADDING)
     {
       avoid_paste = true;
diff --git a/gcc/c-family/c-pragma.h b/gcc/c-family/c-pragma.h
index de806a6..c894a25 100644
--- a/gcc/c-family/c-pragma.h
+++ b/gcc/c-family/c-pragma.h
@@ -108,6 +108,7 @@ enum pragma_omp_clause {
   PRAGMA_OMP_CLAUSE_DEVICE,
   PRAGMA_OMP_CLAUSE_DEVICE_TYPE,
   PRAGMA_OMP_CLAUSE_DIST_SCHEDULE,
+  PRAGMA_OMP_CLAUSE_DOACROSS,
   PRAGMA_OMP_CLAUSE_ENTER,
   PRAGMA_OMP_CLAUSE_FILTER,
   PRAGMA_OMP_CLAUSE_FINAL,
diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
index 71a0cb5..efa1768 100644
--- a/gcc/c-family/c-pretty-print.cc
+++ b/gcc/c-family/c-pretty-print.cc
@@ -321,6 +321,7 @@ pp_c_pointer (c_pretty_printer *pp, tree t)
       _Bool                          -- C99
       _Complex                       -- C99
       _Imaginary                     -- C99
+      nullptr_t                      -- C23
       struct-or-union-specifier
       enum-specifier
       typedef-name.
@@ -424,6 +425,9 @@ c_pretty_printer::simple_type_specifier (tree t)
       else
 	translate_string ("<anonymous>");
       break;
+    case NULLPTR_TYPE:
+      pp_c_ws_string (this, "nullptr_t");
+      break;
 
     default:
       pp_unsupported_tree (this, t);
@@ -678,6 +682,7 @@ c_pretty_printer::direct_abstract_declarator (tree t)
     case COMPLEX_TYPE:
     case TYPE_DECL:
     case ERROR_MARK:
+    case NULLPTR_TYPE:
       break;
 
     default:
@@ -1219,6 +1224,8 @@ c_pretty_printer::constant (tree e)
 	  pp_c_character_constant (this, e);
 	else if (TREE_CODE (type) == ENUMERAL_TYPE)
 	  pp_c_enumeration_constant (this, e);
+	else if (NULLPTR_TYPE_P (type))
+	  pp_string (this, "nullptr");
 	else
 	  pp_c_integer_constant (this, e);
       }
diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc
index ea7335f..6742f44 100644
--- a/gcc/c-family/c-warn.cc
+++ b/gcc/c-family/c-warn.cc
@@ -3799,3 +3799,94 @@ do_warn_array_compare (location_t location, tree_code code, tree op0, tree op1)
 		op0, op_symbol_code (code), op1);
     }
 }
+
+/* Given LHS_VAL ^ RHS_VAL, where LHS_LOC is the location of the LHS and
+   OPERATOR_LOC is the location of the ^, complain with -Wxor-used-as-pow
+   if it looks like the user meant exponentiation rather than xor.  */
+
+void
+check_for_xor_used_as_pow (location_t lhs_loc, tree lhs_val,
+			   location_t operator_loc,
+			   tree rhs_val)
+{
+  /* Only complain if both args are non-negative integer constants that fit
+     in uhwi.  */
+  if (!tree_fits_uhwi_p (lhs_val) || !tree_fits_uhwi_p (rhs_val))
+    return;
+
+  /* Only complain if the LHS is 2 or 10.  */
+  unsigned HOST_WIDE_INT lhs_uhwi = tree_to_uhwi (lhs_val);
+  if (lhs_uhwi != 2 && lhs_uhwi != 10)
+    return;
+
+  unsigned HOST_WIDE_INT rhs_uhwi = tree_to_uhwi (rhs_val);
+  unsigned HOST_WIDE_INT xor_result = lhs_uhwi ^ rhs_uhwi;
+  binary_op_rich_location loc (operator_loc,
+			       lhs_val, rhs_val, false);
+
+  /* If we issue fix-it hints with the warning then we will also issue a
+     note suggesting how to suppress the warning with a different change.
+     These proposed changes are incompatible.  */
+  loc.fixits_cannot_be_auto_applied ();
+
+  auto_diagnostic_group d;
+  bool warned = false;
+  if (lhs_uhwi == 2)
+    {
+      /* Would exponentiation fit in int, in long long, or not at all?  */
+      if (rhs_uhwi < (INT_TYPE_SIZE - 1))
+	{
+	  unsigned HOST_WIDE_INT suggested_result = 1 << rhs_uhwi;
+	  loc.add_fixit_replace (lhs_loc, "1");
+	  loc.add_fixit_replace (operator_loc, "<<");
+	  warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+			       "result of %<%wu^%wu%> is %wu;"
+			       " did you mean %<1 << %wu%> (%wu)?",
+			       lhs_uhwi, rhs_uhwi, xor_result,
+			       rhs_uhwi, suggested_result);
+	}
+      else if (rhs_uhwi < (LONG_LONG_TYPE_SIZE - 1))
+	{
+	  loc.add_fixit_replace (lhs_loc, "1LL");
+	  loc.add_fixit_replace (operator_loc, "<<");
+	  warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+			       "result of %<%wu^%wu%> is %wu;"
+			       " did you mean %<1LL << %wu%>?",
+			       lhs_uhwi, rhs_uhwi, xor_result,
+			       rhs_uhwi);
+	}
+      else if (rhs_uhwi <= LONG_LONG_TYPE_SIZE)
+	warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+			     "result of %<%wu^%wu%> is %wu;"
+			     " did you mean exponentiation?",
+			     lhs_uhwi, rhs_uhwi, xor_result);
+      /* Otherwise assume it's an xor.  */
+    }
+  else
+    {
+      gcc_assert (lhs_uhwi == 10);
+      loc.add_fixit_replace (lhs_loc, "1");
+      loc.add_fixit_replace (operator_loc, "e");
+      warned = warning_at (&loc, OPT_Wxor_used_as_pow,
+			   "result of %<%wu^%wu%> is %wu;"
+			   " did you mean %<1e%wu%>?",
+			   lhs_uhwi, rhs_uhwi, xor_result,
+			   rhs_uhwi);
+    }
+  if (warned)
+    {
+      gcc_rich_location note_loc (lhs_loc);
+      if (lhs_uhwi == 2)
+	note_loc.add_fixit_replace (lhs_loc, "0x2");
+      else
+	{
+	  gcc_assert (lhs_uhwi == 10);
+	  note_loc.add_fixit_replace (lhs_loc, "0xa");
+	}
+      note_loc.fixits_cannot_be_auto_applied ();
+      inform (&note_loc,
+	      "you can silence this warning by using a hexadecimal constant"
+	      " (%wx rather than %wd)",
+	      lhs_uhwi, lhs_uhwi);
+    }
+}
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 44e1a60..1c7f89e 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -455,7 +455,7 @@ Wc++2a-compat
 C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
 
 Wc++20-compat
-C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
+C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
 Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
 
 Wc++11-extensions
@@ -821,6 +821,10 @@ Winvalid-pch
 C ObjC C++ ObjC++ CPP(warn_invalid_pch) CppReason(CPP_W_INVALID_PCH) Var(cpp_warn_invalid_pch) Init(0) Warning
 Warn about PCH files that are found but not used.
 
+Winvalid-utf8
+C ObjC C++ ObjC++ CPP(cpp_warn_invalid_utf8) CppReason(CPP_W_INVALID_UTF8) Var(warn_invalid_utf8) Init(0) Warning
+Warn about invalid UTF-8 characters.
+
 Wjump-misses-init
 C ObjC Var(warn_jump_misses_init) Warning LangEnabledby(C ObjC,Wc++-compat)
 Warn when a jump misses a variable initialization.
@@ -1229,6 +1233,10 @@ Wselector
 ObjC ObjC++ Var(warn_selector) Warning
 Warn if a selector has multiple methods.
 
+Wself-move
+C++ ObjC++ Var(warn_self_move) Warning LangEnabledBy(C++ ObjC++, Wall)
+Warn when a value is moved to itself with std::move.
+
 Wsequence-point
 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
 Warn about possible violations of sequence point rules.
@@ -1337,6 +1345,10 @@ Wundef
 C ObjC C++ ObjC++ CPP(warn_undef) CppReason(CPP_W_UNDEF) Var(cpp_warn_undef) Init(0) Warning
 Warn if an undefined macro is used in an #if directive.
 
+Wunicode
+C ObjC C++ ObjC++ CPP(cpp_warn_unicode) CppReason(CPP_W_UNICODE) Var(warn_unicode) Init(1) Warning
+Warn about invalid forms of delimited or named escape sequences.
+
 Wuninitialized
 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
 ;
@@ -1439,6 +1451,10 @@ Wwrite-strings
 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
 In C++, nonzero means warn about deprecated conversion from string literals to 'char *'.  In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
 
+Wxor-used-as-pow
+C ObjC C++ ObjC++ Var(warn_xor_used_as_pow) Warning Init(1)
+Warn about xor operators where it appears the user meant exponentiation.
+
 Wzero-as-null-pointer-constant
 C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
 Warn when a literal '0' is used as null pointer.