c: Implement C2Y N3298 - Introduce complex literals [PR117029]

The following patch implements the C2Y N3298 paper Introduce complex literals
by providing different (or no) diagnostics on imaginary constants (except
for integer ones).
For _DecimalN constants we don't support _Complex _DecimalN and error on any
i/j suffixes mixed with DD/DL/DF, so nothing changed there.

2024-11-13  Jakub Jelinek  <jakub@redhat.com>

	PR c/117029
libcpp/
	* include/cpplib.h (struct cpp_options): Add imaginary_constants
	member.
	* init.cc (struct lang_flags): Add imaginary_constants bitfield.
	(lang_defaults): Add column for imaginary_constants.
	(cpp_set_lang): Copy over imaginary_constants.
	* expr.cc (cpp_classify_number): Diagnose CPP_N_IMAGINARY
	non-CPP_N_FLOATING constants differently for C.
gcc/testsuite/
	* gcc.dg/cpp/pr7263-3.c: Adjust expected diagnostic wording.
	* gcc.dg/c23-imaginary-constants-1.c: New test.
	* gcc.dg/c23-imaginary-constants-2.c: New test.
	* gcc.dg/c23-imaginary-constants-3.c: New test.
	* gcc.dg/c23-imaginary-constants-4.c: New test.
	* gcc.dg/c23-imaginary-constants-5.c: New test.
	* gcc.dg/c23-imaginary-constants-6.c: New test.
	* gcc.dg/c23-imaginary-constants-7.c: New test.
	* gcc.dg/c23-imaginary-constants-8.c: New test.
	* gcc.dg/c23-imaginary-constants-9.c: New test.
	* gcc.dg/c23-imaginary-constants-10.c: New test.
	* gcc.dg/c2y-imaginary-constants-1.c: New test.
	* gcc.dg/c2y-imaginary-constants-2.c: New test.
	* gcc.dg/c2y-imaginary-constants-3.c: New test.
	* gcc.dg/c2y-imaginary-constants-4.c: New test.
	* gcc.dg/c2y-imaginary-constants-5.c: New test.
	* gcc.dg/c2y-imaginary-constants-6.c: New test.
	* gcc.dg/c2y-imaginary-constants-7.c: New test.
	* gcc.dg/c2y-imaginary-constants-8.c: New test.
	* gcc.dg/c2y-imaginary-constants-9.c: New test.
	* gcc.dg/c2y-imaginary-constants-10.c: New test.
	* gcc.dg/c2y-imaginary-constants-11.c: New test.
	* gcc.dg/c2y-imaginary-constants-12.c: New test.

3 files changed, 56 insertions, 34 deletions

diff --git a/libcpp/expr.cc b/libcpp/expr.cc
index 53980f4..bbf21b8 100644
--- a/libcpp/expr.cc
+++ b/libcpp/expr.cc
@@ -911,8 +911,25 @@ cpp_classify_number (cpp_reader *pfile, const cpp_token *token,
 
  syntax_ok:
   if (result & CPP_N_IMAGINARY)
-    cpp_pedwarning_with_line (pfile, CPP_W_PEDANTIC, virtual_location, 0,
-			      "imaginary constants are a GCC extension");
+    {
+      if (CPP_OPTION (pfile, cplusplus) || (result & CPP_N_FLOATING) == 0)
+	cpp_pedwarning_with_line (pfile, CPP_W_PEDANTIC, virtual_location, 0,
+				  "imaginary constants are a GCC extension");
+      else
+	{
+	  bool warned = false;
+	  if (!CPP_OPTION (pfile, imaginary_constants) && CPP_PEDANTIC (pfile))
+	    warned
+	      = cpp_pedwarning_with_line (pfile, CPP_W_PEDANTIC,
+					  virtual_location, 0,
+					  "imaginary constants are a C2Y "
+					  "feature or GCC extension");
+	  if (!warned && CPP_OPTION (pfile, cpp_warn_c23_c2y_compat) > 0)
+	    cpp_warning_with_line (pfile, CPP_W_C23_C2Y_COMPAT,
+				   virtual_location, 0,
+				   "imaginary constants are a C2Y feature");
+	}
+    }
   if (radix == 2)
     {
       bool warned = false;
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 267d281..e73f77e 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -524,6 +524,9 @@ struct cpp_options
   /* Nonzero for C++ 2014 Standard binary constants.  */
   unsigned char binary_constants;
 
+  /* Nonzero for C2Y imaginary (floating) constants.  */
+  unsigned char imaginary_constants;
+
   /* Nonzero for C++ 2014 Standard digit separators.  */
   unsigned char digit_separators;
 
diff --git a/libcpp/init.cc b/libcpp/init.cc
index c8c466d..355e501 100644
--- a/libcpp/init.cc
+++ b/libcpp/init.cc
@@ -112,44 +112,45 @@ struct lang_flags
   unsigned int octal_constants : 1;
   unsigned int true_false : 1;
   unsigned int embed : 1;
+  unsigned int imaginary_constants : 1;
 };
 
 static const struct lang_flags lang_defaults[] = {
   /*					       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 }
+		       x     i   d u r d n g t h a c   z f n e e c u m i
+		   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 m
+		   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 a
+		   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 g */
+  /* GNUC89   */ { 0,0,1,0,0,0,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0 },
+  /* GNUC99   */ { 1,0,1,1,0,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0 },
+  /* GNUC11   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0 },
+  /* GNUC17   */ { 1,0,1,1,1,0,0,1,1,1,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0 },
+  /* GNUC23   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,0,0,0,1,1,0 },
+  /* GNUC2Y   */ { 1,0,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1,1,0,1,1,1,0,1,1,1,1 },
+  /* STDC89   */ { 0,0,0,0,0,0,1,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC94   */ { 0,0,0,0,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC99   */ { 1,0,1,1,0,0,1,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC11   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC17   */ { 1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0 },
+  /* STDC23   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,0,0,0,1,1,0 },
+  /* STDC2Y   */ { 1,0,1,1,1,1,1,1,1,0,0,1,1,0,1,1,1,1,0,1,1,1,0,1,1,1,1 },
+  /* GNUCXX   */ { 0,1,1,1,0,1,0,1,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* CXX98    */ { 0,1,0,1,0,1,1,1,0,0,0,0,0,1,0,0,1,0,0,0,0,0,0,0,1,0,0 },
+  /* GNUCXX11 */ { 1,1,1,1,1,1,0,1,1,1,1,0,0,0,0,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* CXX11    */ { 1,1,0,1,1,1,1,1,1,1,1,0,0,1,0,0,1,0,0,0,0,0,0,0,1,0,0 },
+  /* GNUCXX14 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,0,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* CXX14    */ { 1,1,0,1,1,1,1,1,1,1,1,1,1,1,0,0,1,0,0,0,0,0,0,0,1,0,0 },
+  /* GNUCXX17 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* CXX17    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,0,1,0,0,0,0,0,0,0,1,0,0 },
+  /* GNUCXX20 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* CXX20    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,0,1,0,0 },
+  /* GNUCXX23 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0,0 },
+  /* CXX23    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0,0 },
+  /* GNUCXX26 */ { 1,1,1,1,1,1,0,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0,0 },
+  /* CXX26    */ { 1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,1,1,1,1,1,0,1,0,0 },
+  /* ASM      */ { 0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
 };
 
 /* Sets internal flags correctly for a given language.  */
@@ -186,6 +187,7 @@ cpp_set_lang (cpp_reader *pfile, enum c_lang lang)
   CPP_OPTION (pfile, octal_constants)		 = l->octal_constants;
   CPP_OPTION (pfile, true_false)		 = l->true_false;
   CPP_OPTION (pfile, embed)			 = l->embed;
+  CPP_OPTION (pfile, imaginary_constants)	 = l->imaginary_constants;
 }
 
 /* Initialize library global state.  */