c, libcpp: Partially implement C2Y N3353 paper [PR117028]

The following patch partially implements the N3353 paper.
In particular, it adds support for the delimited escape sequences
(\u{123}, \x{123}, \o{123}) which were added already for C++23,
all I had to do is split the delimited escape sequence guarding from
named universal character escape sequence guards
(\N{LATIN CAPITAL LETTER C WITH CARON}), which C++23 has but C2Y doesn't
and emit different diagnostics for C from C++ for the delimited escape
sequences.
And it adds support for the new style of octal literals, 0o137 or 0O1777.
I have so far added that just for C and not C++, because I have no idea
whether C++ will want to handle it similarly.

What the patch doesn't do is any kind of diagnostics for obsoletion of
\137 or 0137, as discussed in the PR, I think it is way too early for that.
Perhaps some non-default warning later on.

2024-10-17  Jakub Jelinek  <jakub@redhat.com>

	PR c/117028
libcpp/
	* include/cpplib.h (struct cpp_options): Add named_uc_escape_seqs,
	octal_constants and cpp_warn_c23_c2y_compat members.
	(enum cpp_warning_reason): Add CPP_W_C23_C2Y_COMPAT enumerator.
	* init.cc (struct lang_flags): Add named_uc_escape_seqs and
	octal_constants bit-fields.
	(lang_defaults): Add initializers for them into the table.
	(cpp_set_lang): Initialize named_uc_escape_seqs and octal_constants.
	(cpp_create_reader): Initialize cpp_warn_c23_c2y_compat to -1.
	* charset.cc (_cpp_valid_ucn): Test
	CPP_OPTION (pfile, named_uc_escape_seqs) rather than
	CPP_OPTION (pfile, delimited_escape_seqs) in \N{} related tests.
	Change wording of C cpp_pedwarning for \u{} and emit
	-Wc23-c2y-compat warning for it too if needed.  Formatting fixes.
	(convert_hex): Change wording of C cpp_pedwarning for \u{} and emit
	-Wc23-c2y-compat warning for it too if needed.
	(convert_oct): Likewise.
	* expr.cc (cpp_classify_number): Handle C2Y 0o or 0O prefixed
	octal constants.
	(cpp_interpret_integer): Likewise.
gcc/c-family/
	* c.opt (Wc23-c2y-compat): Add CPP and CppReason parameters.
	* c-opts.cc (set_std_c2y): Use CLK_STDC2Y or CLK_GNUC2Y rather
	than CLK_STDC23 and CLK_GNUC23.  Formatting fix.
	* c-lex.cc (interpret_integer): Handle C2Y 0o or 0O prefixed
	and wb/WB/uwb/UWB suffixed octal constants.
gcc/testsuite/
	* gcc.dg/bitint-112.c: New test.
	* gcc.dg/c23-digit-separators-1.c: Add _Static_assert for
	valid binary constant with digit separator.
	* gcc.dg/c23-octal-constants-1.c: New test.
	* gcc.dg/c23-octal-constants-2.c: New test.
	* gcc.dg/c2y-digit-separators-1.c: New test.
	* gcc.dg/c2y-digit-separators-2.c: New test.
	* gcc.dg/c2y-octal-constants-1.c: New test.
	* gcc.dg/c2y-octal-constants-2.c: New test.
	* gcc.dg/c2y-octal-constants-3.c: New test.
	* gcc.dg/cpp/c23-delimited-escape-seq-1.c: New test.
	* gcc.dg/cpp/c23-delimited-escape-seq-2.c: New test.
	* gcc.dg/cpp/c2y-delimited-escape-seq-1.c: New test.
	* gcc.dg/cpp/c2y-delimited-escape-seq-2.c: New test.
	* gcc.dg/cpp/c2y-delimited-escape-seq-3.c: New test.
	* gcc.dg/cpp/c2y-delimited-escape-seq-4.c: New test.
	* gcc.dg/octal-constants-1.c: New test.
	* gcc.dg/octal-constants-2.c: New test.
	* gcc.dg/octal-constants-3.c: New test.
	* gcc.dg/octal-constants-4.c: New test.
	* gcc.dg/system-octal-constants-1.c: New test.
	* gcc.dg/system-octal-constants-1.h: New file.

1 files changed, 40 insertions, 35 deletions

diff --git a/libcpp/init.cc b/libcpp/init.cc
index 1cc62a4..4789274 100644
--- a/libcpp/init.cc
+++ b/libcpp/init.cc
@@ -108,46 +108,48 @@ struct lang_flags
   unsigned int elifdef : 1;
   unsigned int warning_directive : 1;
   unsigned int delimited_escape_seqs : 1;
+  unsigned int named_uc_escape_seqs : 1;
+  unsigned int octal_constants : 1;
   unsigned int true_false : 1;
   unsigned int embed : 1;
 };
 
 static const struct lang_flags lang_defaults[] = {
-  /*					       u         e w
-					 b d   8         l a   t
-			     x         u i i   c v s   s i r d r e
-		       x     i   d u r d n g t h a c   z f n e u m
-		   c c n x c d s i l l l c s r l o o d l d d l f b
-		   9 + u i 1 i t g i i i s e i i p p f i e i i a e
-		   9 + m d 1 d d r t t t t p g t t e p t f r m l d  */
-  /* GNUC89   */ { 0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0 },
-  /* GNUC99   */ { 1,0,1,1,0,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0 },
-  /* GNUC11   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0 },
-  /* GNUC17   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0 },
-  /* GNUC23   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,0,1,1 },
-  /* GNUC2Y   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,0,1,1 },
-  /* STDC89   */ { 0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0 },
-  /* STDC94   */ { 0,0,0,0,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0 },
-  /* STDC99   */ { 1,0,1,1,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0 },
-  /* STDC11   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0 },
-  /* STDC17   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0 },
-  /* STDC23   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,0,1,1 },
-  /* STDC2Y   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,0,1,1 },
-  /* GNUCXX   */ { 0,1,1,1,0,1,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,1,0 },
-  /* CXX98    */ { 0,1,0,1,0,1,1,1,0,0,0,0,0,1,0,0,1,0,0,0,0,0,1,0 },
-  /* GNUCXX11 */ { 1,1,1,1,1,1,0,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,1,0 },
-  /* CXX11    */ { 1,1,0,1,1,1,1,1,1,1,1,0,0,1,0,0,1,0,0,0,0,0,1,0 },
-  /* GNUCXX14 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,0,1,1,0,0,0,0,0,1,0 },
-  /* CXX14    */ { 1,1,0,1,1,1,1,1,1,1,1,1,1,1,0,0,1,0,0,0,0,0,1,0 },
-  /* GNUCXX17 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,1,0 },
-  /* CXX17    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,0,1,0,0,0,0,0,1,0 },
-  /* GNUCXX20 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,1,0 },
-  /* CXX20    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,1,0 },
-  /* GNUCXX23 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0 },
-  /* CXX23    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0 },
-  /* GNUCXX26 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0 },
-  /* CXX26    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0 },
-  /* ASM      */ { 0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
+  /*					       u         e w   n
+					 b d   8         l a   a   t
+			     x         u i i   c v s   s i r d m o r e
+		       x     i   d u r d n g t h a c   z f n e e c u m
+		   c c n x c d s i l l l c s r l o o d l d d l d t f b
+		   9 + u i 1 i t g i i i s e i i p p f i e i i u a a e
+		   9 + m d 1 d d r t t t t p g t t e p t f r m c l l d  */
+  /* GNUC89   */ { 0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0 },
+  /* GNUC99   */ { 1,0,1,1,0,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0 },
+  /* GNUC11   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0 },
+  /* GNUC17   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0 },
+  /* GNUC23   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,0,0,0,1,1 },
+  /* GNUC2Y   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,1,0,1,1,1 },
+  /* STDC89   */ { 0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC94   */ { 0,0,0,0,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC99   */ { 1,0,1,1,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC11   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC17   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC23   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,0,0,0,1,1 },
+  /* STDC2Y   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,1,0,1,1,1 },
+  /* GNUCXX   */ { 0,1,1,1,0,1,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0 },
+  /* CXX98    */ { 0,1,0,1,0,1,1,1,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,1,0 },
+  /* GNUCXX11 */ { 1,1,1,1,1,1,0,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0 },
+  /* CXX11    */ { 1,1,0,1,1,1,1,1,1,1,1,0,0,1,0,0,1,0,0,0,0,0,0,0,1,0 },
+  /* GNUCXX14 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,0,1,1,0,0,0,0,0,0,0,1,0 },
+  /* CXX14    */ { 1,1,0,1,1,1,1,1,1,1,1,1,1,1,0,0,1,0,0,0,0,0,0,0,1,0 },
+  /* GNUCXX17 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0 },
+  /* CXX17    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,0,1,0,0,0,0,0,0,0,1,0 },
+  /* GNUCXX20 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0 },
+  /* CXX20    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0 },
+  /* GNUCXX23 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0 },
+  /* CXX23    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0 },
+  /* GNUCXX26 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0 },
+  /* CXX26    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0 },
+  /* ASM      */ { 0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
 };
 
 /* Sets internal flags correctly for a given language.  */
@@ -180,6 +182,8 @@ cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
   CPP_OPTION (pfile, elifdef)			 = l->elifdef;
   CPP_OPTION (pfile, warning_directive)		 = l->warning_directive;
   CPP_OPTION (pfile, delimited_escape_seqs)	 = l->delimited_escape_seqs;
+  CPP_OPTION (pfile, named_uc_escape_seqs)	 = l->named_uc_escape_seqs;
+  CPP_OPTION (pfile, octal_constants)		 = l->octal_constants;
   CPP_OPTION (pfile, true_false)		 = l->true_false;
   CPP_OPTION (pfile, embed)			 = l->embed;
 }
@@ -230,6 +234,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table,
   CPP_OPTION (pfile, warn_endif_labels) = 1;
   CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
   CPP_OPTION (pfile, cpp_warn_c11_c23_compat) = -1;
+  CPP_OPTION (pfile, cpp_warn_c23_c2y_compat) = -1;
   CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
   CPP_OPTION (pfile, cpp_warn_cxx20_compat) = 0;
   CPP_OPTION (pfile, cpp_warn_deprecated) = 1;