re PR c/51849 (-Wc99-compat would be considered useful)

	PR c/51849
gcc/
	* gcc/doc/invoke.texi: Document -Wc90-c99-compat.
gcc/c-family/
	* c-opts.c (sanitize_cpp_opts): Pass warn_c90_c99_compat to libcpp.
	* c.opt (Wc90-c99-compat): Add option.
gcc/c/
	* c-decl.c (build_array_declarator): Remove check for !flag_isoc99.
	Call pedwarn_c90 instead of pedwarn.
	(check_bitfield_type_and_width): Likewise.
	(declspecs_add_qual): Likewise.
	(declspecs_add_type): Likewise.
	(warn_variable_length_array): Unify function for -pedantic and -Wvla.
	Adjust to only call pedwarn_c90.
	(grokdeclarator): Remove pedantic && !flag_isoc99 check.  Call
	pedwarn_c90 instead of pedwarn.
	* c-errors.c (pedwarn_c90): Handle -Wc90-c99-compat.
	* c-parser.c (disable_extension_diagnostics): Handle
	warn_c90_c99_compat.
	(restore_extension_diagnostics): Likewise.
	(c_parser_enum_specifier): Remove check for !flag_isoc99.  Call
	pedwarn_c90 instead of pedwarn.
	(c_parser_initelt): Likewise.
	(c_parser_postfix_expression): Likewise.
	(c_parser_postfix_expression_after_paren_type): Likewise.
	(c_parser_compound_statement_nostart): Remove check for !flag_isoc99.
	* c-tree.h: Fix formatting.
	* c-typeck.c (build_array_ref): Remove check for !flag_isoc99.  Call
	pedwarn_c90 instead of pedwarn.
gcc/testsuite/
	* gcc.dg/Wc90-c99-compat-1.c: New test.
	* gcc.dg/Wc90-c99-compat-2.c: New test.
	* gcc.dg/Wc90-c99-compat-3.c: New test.
	* gcc.dg/Wc90-c99-compat-4.c: New test.
	* gcc.dg/Wc90-c99-compat-5.c: New test.
	* gcc.dg/Wc90-c99-compat-6.c: New test.
	* gcc.dg/wvla-1.c: Adjust dg-warning.
	* gcc.dg/wvla-2.c: Adjust dg-warning.
	* gcc.dg/wvla-4.c: Adjust dg-warning.
	* gcc.dg/wvla-6.c: Adjust dg-warning.
libcpp/
	* lex.c (_cpp_lex_direct): Warn when -Wc90-c99-compat is in effect.
	* charset.c (_cpp_valid_ucn): Likewise.
	* include/cpplib.h (cpp_options): Add cpp_warn_c90_c99_compat.
	* macro.c (replace_args): Warn when -Wc90-c99-compat is in effect.
	(parse_params): Likewise.

From-SVN: r213786

5 files changed, 41 insertions, 1 deletions

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index e550d17..54581dd 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,12 @@
+2014-08-10 Marek Polacek  <polacek@redhat.com>
+
+	PR c/51849
+	* lex.c (_cpp_lex_direct): Warn when -Wc90-c99-compat is in effect.
+	* charset.c (_cpp_valid_ucn): Likewise.
+	* include/cpplib.h (cpp_options): Add cpp_warn_c90_c99_compat.
+	* macro.c (replace_args): Warn when -Wc90-c99-compat is in effect.
+	(parse_params): Likewise.
+
 2014-07-27  Marek Polacek  <polacek@redhat.com>
 
 	PR c/61861
diff --git a/libcpp/charset.c b/libcpp/charset.c
index a3c24d6..fa46f92 100644
--- a/libcpp/charset.c
+++ b/libcpp/charset.c
@@ -995,6 +995,10 @@ _cpp_valid_ucn (cpp_reader *pfile, const uchar **pstr,
   if (!CPP_OPTION (pfile, cplusplus) && !CPP_OPTION (pfile, c99))
     cpp_error (pfile, CPP_DL_WARNING,
 	       "universal character names are only valid in C++ and C99");
+  else if (CPP_OPTION (pfile, cpp_warn_c90_c99_compat)
+	   && !CPP_OPTION (pfile, cplusplus))
+    cpp_error (pfile, CPP_DL_WARNING,
+	       "C99's universal character names are incompatible with C90");
   else if (CPP_WTRADITIONAL (pfile) && identifier_pos == 0)
     cpp_warning (pfile, CPP_W_TRADITIONAL,
 	         "the meaning of '\\%c' is different in traditional C",
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index a83452b..4cd66cd 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -466,6 +466,9 @@ struct cpp_options
   /* True if dependencies should be restored from a precompiled header.  */
   bool restore_pch_deps;
 
+  /* True if warn about differences between C90 and C99.  */
+  bool cpp_warn_c90_c99_compat;
+
   /* Dependency generation.  */
   struct
   {
diff --git a/libcpp/lex.c b/libcpp/lex.c
index 7e2db64..5cc2224 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -2325,7 +2325,7 @@ _cpp_lex_direct (cpp_reader *pfile)
       else if (c == '/' && (CPP_OPTION (pfile, cplusplus_comments)
 			    || cpp_in_system_header (pfile)))
 	{
-	  /* Warn about comments only if pedantically GNUC89, and not
+	  /* Warn about comments if pedantically GNUC89, and not
 	     in system headers.  */
 	  if (CPP_OPTION (pfile, lang) == CLK_GNUC89 && CPP_PEDANTIC (pfile)
 	      && ! buffer->warned_cplusplus_comments)
@@ -2336,6 +2336,16 @@ _cpp_lex_direct (cpp_reader *pfile)
 			 "(this will be reported only once per input file)");
 	      buffer->warned_cplusplus_comments = 1;
 	    }
+	  /* Or if specifically desired via -Wc90-c99-compat.  */
+	  else if (CPP_OPTION (pfile, cpp_warn_c90_c99_compat)
+		   && ! buffer->warned_cplusplus_comments)
+	    {
+	      cpp_error (pfile, CPP_DL_WARNING,
+			 "C++ style comments are are incompatible with C90");
+	      cpp_error (pfile, CPP_DL_WARNING,
+			 "(this will be reported only once per input file)");
+	      buffer->warned_cplusplus_comments = 1;
+	    }
 
 	  if (skip_line_comment (pfile) && CPP_OPTION (pfile, warn_comments))
 	    cpp_warning (pfile, CPP_W_COMMENTS, "multi-line comment");
diff --git a/libcpp/macro.c b/libcpp/macro.c
index 556628b..ff6685c 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -1795,6 +1795,16 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
 		       NODE_NAME (node),
 		       src->val.macro_arg.arg_no);
 	}
+      else if (CPP_OPTION (pfile, cpp_warn_c90_c99_compat)
+	       && ! macro->syshdr
+	       && ! cpp_in_system_header (pfile)
+	       && ! CPP_OPTION (pfile, cplusplus))
+	cpp_error (pfile, CPP_DL_WARNING,
+		   "invoking macro %s argument %d: "
+		   "empty macro arguments are undefined"
+		   " in ISO C90",
+		   NODE_NAME (node),
+		   src->val.macro_arg.arg_no);
 
       /* Avoid paste on RHS (even case count == 0).  */
       if (!pfile->state.in_directive && !(src->flags & PASTE_LEFT))
@@ -2848,6 +2858,10 @@ parse_params (cpp_reader *pfile, cpp_macro *macro)
 			(pfile, CPP_W_VARIADIC_MACROS,
 			"anonymous variadic macros were introduced in C99");
 		}
+	      else if (CPP_OPTION (pfile, cpp_warn_c90_c99_compat)
+		       && ! CPP_OPTION (pfile, cplusplus))
+		cpp_error (pfile, CPP_DL_WARNING,
+			   "anonymous variadic macros were introduced in C99");
 	    }
 	  else if (CPP_OPTION (pfile, cpp_pedantic)
 		   && CPP_OPTION (pfile, warn_variadic_macros))