* cppexp.c (struct op): Add token pointer.

	(check_promotion, CHECK_PROMOTION): New.
	(optab): Update.
	(_cpp_parse_expr): Update, use token pointer of struct op.
	(reduce): Warn about change of sign owing to promotion.
	* cppinit.c (cpp_handle_option): New warning if -Wall.
	* cpplib.h (struct cpp_options): New member.
testsuite:
	* gcc.dg/cpp/Wsignprom.c: New tests.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@55611 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6720f50..b20c1b6 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2002-07-20  Neil Booth  <neil@daikokuya.co.uk>
+
+       * cppexp.c (struct op): Add token pointer.
+       (check_promotion, CHECK_PROMOTION): New.
+       (optab): Update.
+       (_cpp_parse_expr): Update, use token pointer of struct op.
+       (reduce): Warn about change of sign owing to promotion.
+       * cppinit.c (cpp_handle_option): New warning if -Wall.
+       * cpplib.h (struct cpp_options): New member.
+
 2002-07-19  David Edelsohn  <edelsohn@gnu.org>
 
        * config/rs6000/rs6000.md: Remove ppc630 fpcompare from single

diff --git a/gcc/cppexp.c b/gcc/cppexp.c
index 5853844..b66fea9 100644 (file)
--- a/gcc/cppexp.c
+++ b/gcc/cppexp.c
@@ -30,6 +30,7 @@ Boston, MA 02111-1307, USA.  */
 
 struct op
 {
+  const cpp_token *token;      /* The token forming op (for diagnostics).  */
   cpp_num value;               /* The value logically "right" of op.  */
   enum cpp_ttype op;
 };
@@ -64,6 +65,7 @@ static cpp_num eval_token PARAMS ((cpp_reader *, const cpp_token *));
 static struct op *reduce PARAMS ((cpp_reader *, struct op *, enum cpp_ttype));
 static unsigned int interpret_float_suffix PARAMS ((const uchar *, size_t));
 static unsigned int interpret_int_suffix PARAMS ((const uchar *, size_t));
+static void check_promotion PARAMS ((cpp_reader *, const struct op *));
 
 /* Token type abuse to create unary plus and minus operators.  */
 #define CPP_UPLUS (CPP_LAST_CPP_OP + 1)
@@ -630,9 +632,11 @@ The parser assumes all shifted operators require a left operand unless
 the flag NO_L_OPERAND is set.  These semantics are automatic; any
 extra semantics need to be handled with operator-specific code.  */
 
-/* Flags.  */
+/* Flags.  If CHECK_PROMOTION, we warn if the effective sign of an
+   operand changes because of integer promotions.  */
 #define NO_L_OPERAND   (1 << 0)
 #define LEFT_ASSOC     (1 << 1)
+#define CHECK_PROMOTION        (1 << 2)
 
 /* Operator to priority map.  Must be in the same order as the first
    N entries of enum cpp_ttype.  */
@@ -644,35 +648,35 @@ static const struct operator
 {
   /* EQ */             {0, 0}, /* Shouldn't happen.  */
   /* NOT */            {16, NO_L_OPERAND},
-  /* GREATER */                {12, LEFT_ASSOC},
-  /* LESS */           {12, LEFT_ASSOC},
-  /* PLUS */           {14, LEFT_ASSOC},
-  /* MINUS */          {14, LEFT_ASSOC},
-  /* MULT */           {15, LEFT_ASSOC},
-  /* DIV */            {15, LEFT_ASSOC},
-  /* MOD */            {15, LEFT_ASSOC},
-  /* AND */            {9, LEFT_ASSOC},
-  /* OR */             {7, LEFT_ASSOC},
-  /* XOR */            {8, LEFT_ASSOC},
+  /* GREATER */                {12, LEFT_ASSOC | CHECK_PROMOTION},
+  /* LESS */           {12, LEFT_ASSOC | CHECK_PROMOTION},
+  /* PLUS */           {14, LEFT_ASSOC | CHECK_PROMOTION},
+  /* MINUS */          {14, LEFT_ASSOC | CHECK_PROMOTION},
+  /* MULT */           {15, LEFT_ASSOC | CHECK_PROMOTION},
+  /* DIV */            {15, LEFT_ASSOC | CHECK_PROMOTION},
+  /* MOD */            {15, LEFT_ASSOC | CHECK_PROMOTION},
+  /* AND */            {9, LEFT_ASSOC | CHECK_PROMOTION},
+  /* OR */             {7, LEFT_ASSOC | CHECK_PROMOTION},
+  /* XOR */            {8, LEFT_ASSOC | CHECK_PROMOTION},
   /* RSHIFT */         {13, LEFT_ASSOC},
   /* LSHIFT */         {13, LEFT_ASSOC},
 
-  /* MIN */            {10, LEFT_ASSOC},
-  /* MAX */            {10, LEFT_ASSOC},
+  /* MIN */            {10, LEFT_ASSOC | CHECK_PROMOTION},
+  /* MAX */            {10, LEFT_ASSOC | CHECK_PROMOTION},
 
   /* COMPL */          {16, NO_L_OPERAND},
   /* AND_AND */                {6, LEFT_ASSOC},
   /* OR_OR */          {5, LEFT_ASSOC},
   /* QUERY */          {3, 0},
-  /* COLON */          {4, LEFT_ASSOC},
+  /* COLON */          {4, LEFT_ASSOC | CHECK_PROMOTION},
   /* COMMA */          {2, LEFT_ASSOC},
   /* OPEN_PAREN */     {1, NO_L_OPERAND},
   /* CLOSE_PAREN */    {0, 0},
   /* EOF */            {0, 0},
   /* EQ_EQ */          {11, LEFT_ASSOC},
   /* NOT_EQ */         {11, LEFT_ASSOC},
-  /* GREATER_EQ */     {12, LEFT_ASSOC},
-  /* LESS_EQ */                {12, LEFT_ASSOC},
+  /* GREATER_EQ */     {12, LEFT_ASSOC | CHECK_PROMOTION},
+  /* LESS_EQ */                {12, LEFT_ASSOC | CHECK_PROMOTION},
   /* UPLUS */          {16, NO_L_OPERAND},
   /* UMINUS */         {16, NO_L_OPERAND}
 };
@@ -693,7 +697,6 @@ _cpp_parse_expr (pfile)
      cpp_reader *pfile;
 {
   struct op *top = pfile->op_stack;
-  const cpp_token *token = NULL, *prev_token;
   unsigned int lex_count;
   bool saw_leading_not, want_value = true;
 
@@ -711,10 +714,9 @@ _cpp_parse_expr (pfile)
     {
       struct op op;
 
-      prev_token = token;
-      token = cpp_get_token (pfile);
       lex_count++;
-      op.op = token->type;
+      op.token = cpp_get_token (pfile);
+      op.op = op.token->type;
 
       switch (op.op)
        {
@@ -726,9 +728,9 @@ _cpp_parse_expr (pfile)
        case CPP_HASH:
          if (!want_value)
            SYNTAX_ERROR2 ("missing binary operator before token \"%s\"",
-                          cpp_token_as_text (pfile, token));
+                          cpp_token_as_text (pfile, op.token));
          want_value = false;
-         top->value = eval_token (pfile, token);
+         top->value = eval_token (pfile, op.token);
          continue;
 
        case CPP_NOT:
@@ -743,15 +745,16 @@ _cpp_parse_expr (pfile)
            op.op = CPP_UMINUS;
          break;
        case CPP_OTHER:
-         if (ISGRAPH (token->val.c))
-           SYNTAX_ERROR2 ("invalid character '%c' in #if", token->val.c);
+         if (ISGRAPH (op.token->val.c))
+           SYNTAX_ERROR2 ("invalid character '%c' in #if", op.token->val.c);
          else
-           SYNTAX_ERROR2 ("invalid character '\\%03o' in #if", token->val.c);
+           SYNTAX_ERROR2 ("invalid character '\\%03o' in #if",
+                          op.token->val.c);
 
        default:
          if ((int) op.op <= (int) CPP_EQ || (int) op.op >= (int) CPP_PLUS_EQ)
            SYNTAX_ERROR2 ("token \"%s\" is not valid in preprocessor expressions",
-                          cpp_token_as_text (pfile, token));
+                          cpp_token_as_text (pfile, op.token));
          break;
        }
 
@@ -760,7 +763,7 @@ _cpp_parse_expr (pfile)
        {
          if (!want_value)
            SYNTAX_ERROR2 ("missing binary operator before token \"%s\"",
-                          cpp_token_as_text (pfile, token));
+                          cpp_token_as_text (pfile, op.token));
        }
       else if (want_value)
        {
@@ -775,7 +778,7 @@ _cpp_parse_expr (pfile)
            SYNTAX_ERROR ("#if with no expression");
          if (top->op != CPP_EOF && top->op != CPP_OPEN_PAREN)
            SYNTAX_ERROR2 ("operator '%s' has no right operand",
-                          cpp_token_as_text (pfile, prev_token));
+                          cpp_token_as_text (pfile, top->token));
        }
 
       top = reduce (pfile, top, op.op);
@@ -816,6 +819,7 @@ _cpp_parse_expr (pfile)
        top = _cpp_expand_op_stack (pfile);
 
       top->op = op.op;
+      top->token = op.token;
     }
 
   /* The controlling macro expression is only valid if we called lex 3
@@ -860,6 +864,10 @@ reduce (pfile, top, op)
   prio = optab[op].prio - ((optab[op].flags & LEFT_ASSOC) != 0);
   while (prio < optab[top->op].prio)
     {
+      if (CPP_OPTION (pfile, warn_num_sign_change)
+         && optab[top->op].flags & CHECK_PROMOTION)
+       check_promotion (pfile, top);
+
       switch (top->op)
        {
        case CPP_UPLUS:
@@ -994,6 +1002,29 @@ _cpp_expand_op_stack (pfile)
   return pfile->op_stack + old_size;
 }
 
+/* Emits a warning if the effective sign of either operand of OP
+   changes because of integer promotions.  */
+static void
+check_promotion (pfile, op)
+     cpp_reader *pfile;
+     const struct op *op;
+{
+  if (op->value.unsignedp == op[-1].value.unsignedp)
+    return;
+
+  if (op->value.unsignedp)
+    {
+      if (!num_positive (op[-1].value, CPP_OPTION (pfile, precision)))
+       cpp_error (pfile, DL_WARNING,
+                  "the left operand of \"%s\" changes sign when promoted",
+                  cpp_token_as_text (pfile, op->token));
+    }
+  else if (!num_positive (op->value, CPP_OPTION (pfile, precision)))
+    cpp_error (pfile, DL_WARNING,
+              "the right operand of \"%s\" changes sign when promoted",
+              cpp_token_as_text (pfile, op->token));
+}
+
 /* Clears the unused high order bits of the number pointed to by PNUM.  */
 static cpp_num
 num_trim (num, precision)

diff --git a/gcc/cppinit.c b/gcc/cppinit.c
index db1314d..72e26ce 100644 (file)
--- a/gcc/cppinit.c
+++ b/gcc/cppinit.c
@@ -1672,6 +1672,7 @@ cpp_handle_option (pfile, argc, argv)
        case OPT_Wall:
          CPP_OPTION (pfile, warn_trigraphs) = 1;
          CPP_OPTION (pfile, warn_comments) = 1;
+         CPP_OPTION (pfile, warn_num_sign_change) = 1;
          break;
 
        case OPT_Wtraditional:

diff --git a/gcc/cpplib.h b/gcc/cpplib.h
index 7c1fe85..c407321 100644 (file)
--- a/gcc/cpplib.h
+++ b/gcc/cpplib.h
@@ -333,6 +333,10 @@ struct cpp_options
   /* Nonzero means warn about text after an #endif (or #else).  */
   unsigned char warn_endif_labels;
 
+  /* Nonzero means warn about implicit sign changes owing to integer
+     promotions.  */
+  unsigned char warn_num_sign_change;
+
   /* Nonzero means turn warnings into errors.  */
   unsigned char warnings_are_errors;
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1665509..91c63ea 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2002-07-20  Neil Booth  <neil@daikokuya.co.uk>
+
+       * gcc.dg/cpp/Wsignprom.c: New tests.
+
 2002-07-20  Alan Modra  <amodra@bigpond.net.au>
 
        * gcc.c-torture/execute/loop-13.c: New test.

diff --git a/gcc/testsuite/gcc.dg/cpp/Wsignprom.c b/gcc/testsuite/gcc.dg/cpp/Wsignprom.c
new file mode 100644 (file)
index 0000000..44b5667
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/Wsignprom.c
@@ -0,0 +1,26 @@
+/* { dg-do preprocess } */
+/* { dg-options "-Wall" } */
+
+/* Test that -Wall emits the warnings about integer promotion changing
+   the sign of an operand.  */
+
+#if -1 > 0U  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if 0U + -1  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if 0U * -1  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if 1U / -2  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if -1 % 1U  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if 1 ? 0U : -1  /* { dg-warning "changes sign when promoted" } */
+#endif
+
+#if 1 ? -1 : 0U  /* { dg-warning "changes sign when promoted" } */
+#endif