* c-common.c (warn_multichar): New.

	(c_common_init): Set CPP's warn_multichar.
	* c-common.h (warn_multichar): New.
	* c-decl.c (warn_multichar): Remove.
	* c-lex.c (lex_charconst): Update.
	* c-tree.h (warn_multichar): Remove.
	* cppexp.c (eval_token): Sign-extend charconst value.
	* cppinit.c (cpp_create_reader): Set warn_multichar.
	* cpplex.c (cpp_interpret_charconst): Don't sign-extend
	each character.  Update prototype.  Sign-extend the result.
	* cpplib.h: Fix conditions.
	(struct cpp_options): Add new warning flag.
	(cpp_interpret_charconst): Update prototype.
cp:
	* Make-lang.in (decl2.o): Update.
	* cp-tree.h (warn_multichar): Remove.
	* decl2.c: Include c-common.h.
	(warn_multichar): Remove.
doc:
	* cpp.texi: Update documentation.
testsuite:
	* gcc.dg/cpp/charconst-3.c: Correct tests accordingly.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@53240 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 7 deletions

diff --git a/gcc/cpplex.c b/gcc/cpplex.c
index d3268985697..a9f14948133 100644
--- a/gcc/cpplex.c
+++ b/gcc/cpplex.c
@@ -1861,10 +1861,9 @@ cpp_parse_escape (pfile, pstr, limit, wide)
    characters seen, and UNSIGNEDP to a variable that indicates whether
    the result has signed type.  */
 cppchar_t
-cpp_interpret_charconst (pfile, token, warn_multi, pchars_seen, unsignedp)
+cpp_interpret_charconst (pfile, token, pchars_seen, unsignedp)
      cpp_reader *pfile;
      const cpp_token *token;
-     int warn_multi;
      unsigned int *pchars_seen;
      int *unsignedp;
 {
@@ -1930,11 +1929,10 @@ cpp_interpret_charconst (pfile, token, warn_multi, pchars_seen, unsignedp)
       
       chars_seen++;
 
-      /* Sign-extend the character, scale result, and add the two.  */
-      if (!unsigned_p && (c & (1 << (width - 1))))
-	c |= ~mask;
+      /* Truncate the character, scale the result and merge the two.  */
+      c &= mask;
       if (width < BITS_PER_CPPCHAR_T)
-	result = (result << width) + c;
+	result = (result << width) | c;
       else
 	result = c;
     }
@@ -1945,16 +1943,29 @@ cpp_interpret_charconst (pfile, token, warn_multi, pchars_seen, unsignedp)
     {
       /* Multichar charconsts are of type int and therefore signed.  */
       unsigned_p = 0;
+
       if (chars_seen > max_chars)
 	{
 	  chars_seen = max_chars;
 	  cpp_error (pfile, DL_WARNING,
 		     "character constant too long for its type");
 	}
-      else if (warn_multi)
+      else if (CPP_OPTION (pfile, warn_multichar))
 	cpp_error (pfile, DL_WARNING, "multi-character character constant");
     }
 
+  /* Sign-extend the constant.  */
+  if (!unsigned_p)
+    {
+      size_t precision = width;
+
+      if (chars_seen > 1)
+	precision *= max_chars;
+      if (precision < BITS_PER_CPPCHAR_T
+	  && (result & ((cppchar_t) 1 << (precision - 1))))
+	result |= ~(((cppchar_t) 1 << precision) - 1);
+    }
+
   *pchars_seen = chars_seen;
   *unsignedp = unsigned_p;
   return result;