re PR preprocessor/20077 (GCC accepts macro definitions that fail a constraint)

2007-05-23  Simon Martin  <simartin@users.sourceforge.net>

	PR preprocessor/20077
	* macro.c (create_iso_definition): Fixed the method to determine whether
	the token-pasting operator appears at the beginning or the end of a macro.

From-SVN: r125000

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2007-05-23  Simon Martin  <simartin@users.sourceforge.net>
+
+	PR preprocessor/20077
+	* gcc.dg/cpp/paste15.c: New test.
+
 2007-05-23  Sandra Loosemore  <sandra@codesourcery.com>
 	    Nigel Stephens  <nigel@mips.com>
 	    Richard Sandiford  <richard@codesourcery.com>

gcc/testsuite/gcc.dg/cpp/paste15.c

@@ -0,0 +1,15 @@
+/* PR preprocessor/20077 */
+/* { dg-do preprocess } */
+
+#define a   a ## ## /* { dg-error "end of a macro expansion" } */
+#define b() b ## ## /* { dg-error "end of a macro expansion" } */
+#define c   c ##    /* { dg-error "end of a macro expansion" } */
+#define d() d ##    /* { dg-error "end of a macro expansion" } */
+
+
+#define e   ## ## e /* { dg-error "end of a macro expansion" } */
+#define f() ## ## f /* { dg-error "end of a macro expansion" } */
+#define g   ## g    /* { dg-error "end of a macro expansion" } */
+#define h() ## h    /* { dg-error "end of a macro expansion" } */
+#define i   ##      /* { dg-error "end of a macro expansion" } */
+#define j() ##      /* { dg-error "end of a macro expansion" } */

libcpp/ChangeLog

@@ -1,3 +1,10 @@
+2007-05-23  Simon Martin  <simartin@users.sourceforge.net>
+
+	PR preprocessor/20077
+	* macro.c (create_iso_definition): Fixed the method to determine
+	whether the token-pasting operator appears at the beginning or the end
+	of a macro.
+
 2007-05-21  Ian Lance Taylor  <iant@google.com>
 
 	* internal.h (struct cpp_reader): Add new fields:

libcpp/macro.c

@@ -1434,6 +1434,9 @@ create_iso_definition (cpp_reader *pfile, cpp_macro *macro)
 {
   cpp_token *token;
   const cpp_token *ctoken;
+  bool following_paste_op = false;
+  const char *paste_op_error_msg =
+    N_("'##' cannot appear at either end of a macro expansion");
 
   /* Get the first token of the expansion (or the '(' of a
      function-like macro).  */
@@ -1527,26 +1530,34 @@ create_iso_definition (cpp_reader *pfile, cpp_macro *macro)
 	}
 
       if (token->type == CPP_EOF)
+	{
+	  /* Paste operator constraint 6.10.3.3.1:
+	     Token-paste ##, can appear in both object-like and
+	     function-like macros, but not at the end.  */
+	  if (following_paste_op)
+	    {
+	      cpp_error (pfile, CPP_DL_ERROR, paste_op_error_msg);
+	      return false;
+	    }
 	  break;
+	}
 
       /* Paste operator constraint 6.10.3.3.1.  */
       if (token->type == CPP_PASTE)
 	{
 	  /* Token-paste ##, can appear in both object-like and
-	     function-like macros, but not at the ends.  */
+	     function-like macros, but not at the beginning.  */
-	  if (--macro->count > 0)
+	  if (macro->count == 1)
-	    token = lex_expansion_token (pfile, macro);
-
-	  if (macro->count == 0 || token->type == CPP_EOF)
 	    {
-	      cpp_error (pfile, CPP_DL_ERROR,
+	      cpp_error (pfile, CPP_DL_ERROR, paste_op_error_msg);
-		 "'##' cannot appear at either end of a macro expansion");
 	      return false;
 	    }
 
+	  --macro->count;
 	  token[-1].flags |= PASTE_LEFT;
 	}
 
+      following_paste_op = (token->type == CPP_PASTE);
       token = lex_expansion_token (pfile, macro);
     }