diff mbox series

[1/3] C: Implement C2X N2653 char8_t and UTF-8 string literal changes

Message ID 20220725175948.1424695-2-tom@honermann.net
State New
Headers
Series Implement C2X N2653 (char8_t) and correct UTF-8 character literal type in preprocessor directives for C++ |

Commit Message

Tom Honermann July 25, 2022, 5:59 p.m. UTC 
  This patch implements the core language and compiler dependent library
changes adopted for C2X via WG14 N2653.  The changes include:
- Change of type for UTF-8 string literals from array of const char to
  array of const char8_t (unsigned char).
- A new atomic_char8_t typedef.
- A new ATOMIC_CHAR8_T_LOCK_FREE macro defined in terms of the existing
  __GCC_ATOMIC_CHAR8_T_LOCK_FREE predefined macro.

gcc/ChangeLog:

	* ginclude/stdatomic.h (atomic_char8_t,
	ATOMIC_CHAR8_T_LOCK_FREE): New typedef and macro.

gcc/c/ChangeLog:

	* c-parser.c (c_parser_string_literal): Use char8_t as the type
	of CPP_UTF8STRING when char8_t support is enabled.
	* c-typeck.c (digest_init): Allow initialization of an array
	of character type by a string literal with type array of
	char8_t.

gcc/c-family/ChangeLog:

	* c-lex.c (lex_string, lex_charconst): Use char8_t as the type
	of CPP_UTF8CHAR and CPP_UTF8STRING when char8_t support is
	enabled.
	* c-opts.c (c_common_post_options): Set flag_char8_t if
	targeting C2x.
---
 gcc/c-family/c-lex.cc    | 13 +++++++++----
 gcc/c-family/c-opts.cc   |  4 ++--
 gcc/c/c-parser.cc        | 16 ++++++++++++++--
 gcc/c/c-typeck.cc        |  2 +-
 gcc/ginclude/stdatomic.h |  8 ++++++++
 5 files changed, 34 insertions(+), 9 deletions(-)

Comments

Joseph Myers July 27, 2022, 11:20 p.m. UTC | #1 
On Mon, 25 Jul 2022, Tom Honermann via Gcc-patches wrote:

> diff --git a/gcc/ginclude/stdatomic.h b/gcc/ginclude/stdatomic.h
> index bfcfdf664c7..75ed7965689 100644
> --- a/gcc/ginclude/stdatomic.h
> +++ b/gcc/ginclude/stdatomic.h
> @@ -49,6 +49,10 @@ typedef _Atomic long atomic_long;
>  typedef _Atomic unsigned long atomic_ulong;
>  typedef _Atomic long long atomic_llong;
>  typedef _Atomic unsigned long long atomic_ullong;
> +#if (defined(__CHAR8_TYPE__) \
> +     && (defined(_GNU_SOURCE) || defined(_ISOC2X_SOURCE)))
> +typedef _Atomic __CHAR8_TYPE__ atomic_char8_t;
> +#endif
>  typedef _Atomic __CHAR16_TYPE__ atomic_char16_t;
>  typedef _Atomic __CHAR32_TYPE__ atomic_char32_t;
>  typedef _Atomic __WCHAR_TYPE__ atomic_wchar_t;

GCC headers don't test glibc feature test macros such as _GNU_SOURCE and 
_ISOC2X_SOURCE; they base things only on the standard version (whether 
directly, or indirectly as via __CHAR8_TYPE__) and standard-defined 
feature test macros.

(There's one exception in glimits.h - testing __USE_GNU, the macro defined 
internally by glibc's headers - but I don't think that's something we want 
to emulate in new code.)
Tom Honermann July 30, 2022, 11:17 p.m. UTC | #2 
On 7/27/22 7:20 PM, Joseph Myers wrote:
> On Mon, 25 Jul 2022, Tom Honermann via Gcc-patches wrote:
>
>> diff --git a/gcc/ginclude/stdatomic.h b/gcc/ginclude/stdatomic.h
>> index bfcfdf664c7..75ed7965689 100644
>> --- a/gcc/ginclude/stdatomic.h
>> +++ b/gcc/ginclude/stdatomic.h
>> @@ -49,6 +49,10 @@ typedef _Atomic long atomic_long;
>>   typedef _Atomic unsigned long atomic_ulong;
>>   typedef _Atomic long long atomic_llong;
>>   typedef _Atomic unsigned long long atomic_ullong;
>> +#if (defined(__CHAR8_TYPE__) \
>> +     && (defined(_GNU_SOURCE) || defined(_ISOC2X_SOURCE)))
>> +typedef _Atomic __CHAR8_TYPE__ atomic_char8_t;
>> +#endif
>>   typedef _Atomic __CHAR16_TYPE__ atomic_char16_t;
>>   typedef _Atomic __CHAR32_TYPE__ atomic_char32_t;
>>   typedef _Atomic __WCHAR_TYPE__ atomic_wchar_t;
> GCC headers don't test glibc feature test macros such as _GNU_SOURCE and
> _ISOC2X_SOURCE; they base things only on the standard version (whether
> directly, or indirectly as via __CHAR8_TYPE__) and standard-defined
> feature test macros.

Ok, thank you, that makes sense. I'll follow up with a revised patch 
that removes the additional conditions.

Tom.

>
> (There's one exception in glimits.h - testing __USE_GNU, the macro defined
> internally by glibc's headers - but I don't think that's something we want
> to emulate in new code.)
>
diff mbox series

Patch

diff --git a/gcc/c-family/c-lex.cc b/gcc/c-family/c-lex.cc
index 8bfa4f4024f..0b6f94e18a8 100644
--- a/gcc/c-family/c-lex.cc
+++ b/gcc/c-family/c-lex.cc
@@ -1352,7 +1352,14 @@  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 +1432,7 @@  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-opts.cc b/gcc/c-family/c-opts.cc
index b9f01a65ed7..108adc5caf8 100644
--- a/gcc/c-family/c-opts.cc
+++ b/gcc/c-family/c-opts.cc
@@ -1059,9 +1059,9 @@  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;
 
   if (flag_extern_tls_init)
     {
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 92049d1a101..fa9395986de 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -7447,7 +7447,14 @@  c_parser_string_literal (c_parser *parser, bool translate, bool wide_ok)
 	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)
@@ -7472,9 +7479,14 @@  c_parser_string_literal (c_parser *parser, bool translate, bool wide_ok)
     {
     default:
     case CPP_STRING:
-    case CPP_UTF8STRING:
       TREE_TYPE (value) = char_array_type_node;
       break;
+    case CPP_UTF8STRING:
+      if (flag_char8_t)
+	TREE_TYPE (value) = char8_array_type_node;
+      else
+	TREE_TYPE (value) = char_array_type_node;
+      break;
     case CPP_STRING16:
       TREE_TYPE (value) = char16_array_type_node;
       break;
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index fd0a7f81a7a..231f4e980b6 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -8045,7 +8045,7 @@  digest_init (location_t init_loc, tree type, tree init, tree origtype,
 
 	  if (char_array)
 	    {
-	      if (typ2 != char_type_node)
+	      if (typ2 != char_type_node && typ2 != char8_type_node)
 		incompat_string_cst = true;
 	    }
 	  else if (!comptypes (typ1, typ2))
diff --git a/gcc/ginclude/stdatomic.h b/gcc/ginclude/stdatomic.h
index bfcfdf664c7..75ed7965689 100644
--- a/gcc/ginclude/stdatomic.h
+++ b/gcc/ginclude/stdatomic.h
@@ -49,6 +49,10 @@  typedef _Atomic long atomic_long;
 typedef _Atomic unsigned long atomic_ulong;
 typedef _Atomic long long atomic_llong;
 typedef _Atomic unsigned long long atomic_ullong;
+#if (defined(__CHAR8_TYPE__) \
+     && (defined(_GNU_SOURCE) || defined(_ISOC2X_SOURCE)))
+typedef _Atomic __CHAR8_TYPE__ atomic_char8_t;
+#endif
 typedef _Atomic __CHAR16_TYPE__ atomic_char16_t;
 typedef _Atomic __CHAR32_TYPE__ atomic_char32_t;
 typedef _Atomic __WCHAR_TYPE__ atomic_wchar_t;
@@ -97,6 +101,10 @@  extern void atomic_signal_fence (memory_order);
 
 #define ATOMIC_BOOL_LOCK_FREE		__GCC_ATOMIC_BOOL_LOCK_FREE
 #define ATOMIC_CHAR_LOCK_FREE		__GCC_ATOMIC_CHAR_LOCK_FREE
+#if (defined(__GCC_ATOMIC_CHAR8_T_LOCK_FREE) \
+     && (defined(_GNU_SOURCE) || defined(_ISOC2X_SOURCE)))
+#define ATOMIC_CHAR8_T_LOCK_FREE	__GCC_ATOMIC_CHAR8_T_LOCK_FREE
+#endif
 #define ATOMIC_CHAR16_T_LOCK_FREE	__GCC_ATOMIC_CHAR16_T_LOCK_FREE
 #define ATOMIC_CHAR32_T_LOCK_FREE	__GCC_ATOMIC_CHAR32_T_LOCK_FREE
 #define ATOMIC_WCHAR_T_LOCK_FREE	__GCC_ATOMIC_WCHAR_T_LOCK_FREE