Patchwork [C] Fix pr44517

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Submitter Shujing Zhao
Date June 24, 2010, 9:19 a.m.
Message ID <4C232325.2020107@oracle.com>
Download mbox | patch
Permalink /patch/56772/
State New
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Comments

Shujing Zhao - June 24, 2010, 9:19 a.m.
On 06/23/2010 08:23 PM, Joseph S. Myers wrote:
> On Wed, 23 Jun 2010, Manuel López-Ibáñez wrote:
> 
>> On 23 June 2010 13:45, Joseph S. Myers <joseph@codesourcery.com> wrote:
>>> token->value when it is NULL.  As I said, use it *only* for tokens that
>>> are some kind of identifier (CPP_NAME or CPP_KEYWORD); include testcases
>>> for both CPP_NAME and CPP_KEYWORD and for other kinds of token.
>>>
>>> void f(int a, *b);
>> What other types of tokens can be found at this point?
> 
> That is a matter for the patch submitter to assess and explain as part of 
> justifying the patch; understanding the circumstances in which particular 
> code is reached is an important part of patching the parser.
> 
>> How to print them properly?
> 
> c_parse_error deals with printing different kinds of tokens, although not 
> necessarily optimally.
> 
>> I guess for other types of tokens the "unknown type" message may not
>> be appropriate at all. Perhaps for those cases, the old message:
>>
>> -      c_parser_error (parser,
>> -                     "expected declaration specifiers or %<...%>");
>>
>> would still be appropriate.
> 
> That might also be the case for keywords; saying that e.g. "goto" is an 
> unknown type may not be appropriate.
> 
>>>> +/* PR c/44517: Improve diagnostic for misspelled typename in function declaration. */
>>>> +int foo(int x, pid_t y, long z, in t) {  /* { dg-error "unknown type name 'pid_t'|unknown type name 'in'" } */
>>>> +  return x + y + z + t;
>>>> +}
>>>> +
>>>> +int bar(int x, lon y, long z, ...){ /* { dg-error "unknown type name 'lon'" } */
>>>> +  return;
>>>> +}
>>>> +
>>>> +void foo(int n, int a[n], pid_t x); /* { dg-error "unknown type name 'pid_t'" } */
>>>> +void bar() {};
>>> Use four different names for the four different functions.  Remove the
>>> stray semicolon after your last function body.
>> How can this test pass then? Perhaps it needs an explicit /* { dg-do
>> compile } */ ?
> 
> No, that's the default.  Probably the details of how syntactically 
> erroneous function declarations are handled mean that conflicts do not end 
> up being reported for conflicting types or multiple definitions (if one 
> declaration cannot be parsed, it may not be possible to get a useful idea 
> of whether the types conflict or not).  But since the point of this test 
> is not the details of whether duplicate declarations are diagnosed when 
> those declarations are erroneous in other ways, different names should be 
> used so the test doesn't depend on those details.
> 
Thanks. According to the above discussion, if the token type is CPP_NAME and the 
followed token is not ')' or ',', the error message would be "unknown type name 
%qE". If the token type is CPP_NAME, but followed by ',' or ')', it looks like 
only parameter name is declared and declaration specifier is missed. The old 
message is more appropriate. If the token type is CPP_KEYWORD, such as 'goto', 
the old error message is appropriate. If the token type is the others, it would 
still use the old message.
More cases are added to the test case to test this changes.
Is it right?

Thanks
Pearly
Joseph S. Myers - June 24, 2010, 11:20 a.m.
On Thu, 24 Jun 2010, Shujing Zhao wrote:

> Thanks. According to the above discussion, if the token type is CPP_NAME and
> the followed token is not ')' or ',', the error message would be "unknown type
> name %qE". If the token type is CPP_NAME, but followed by ',' or ')', it looks
> like only parameter name is declared and declaration specifier is missed. The
> old message is more appropriate. If the token type is CPP_KEYWORD, such as

Rather than saying the old message is more appropriate, I'd say that you 
can't really tell the difference between (int, pid_t) where a type was 
undeclared and (int a, b) where a type name is needed before "b".  So 
perhaps the messages should say that either a type is undeclared or a type 
is missing before a parameter name.  (Actually, I'd guess that almost all 
function prototypes either name all parameters or no parameters, so in the 
first case it's a very good guess that pid_t is a type and in the second 
it's a very good guess that b is a parameter name.  But that's definitely 
an enhancement for the future.)

The patch is OK without further code changes needed but with one testcase 
fix:

> +int f1(int x, pid_t y, long z, in t) {  /* { dg-error "unknown type name 'pid_t'|unknown type name 'in'" } */

Please use two separate dg-error directives to match the two separate 
error messages.  The second one would use the form with a line number, { 
dg-error "message" "test name" { target *-*-* } line-number }.

Patch

Index: c-parser.c
===================================================================
--- c-parser.c	(revision 160889)
+++ c-parser.c	(working copy)
@@ -2706,7 +2706,7 @@  c_parser_parms_declarator (c_parser *par
 static struct c_arg_info *
 c_parser_parms_list_declarator (c_parser *parser, tree attrs)
 {
-  bool good_parm = false;
+  bool bad_parm = false;
   /* ??? Following the old parser, forward parameter declarations may
      use abstract declarators, and if no real parameter declarations
      follow the forward declarations then this is not diagnosed.  Also
@@ -2758,11 +2758,10 @@  c_parser_parms_list_declarator (c_parser
       /* Parse a parameter.  */
       struct c_parm *parm = c_parser_parameter_declaration (parser, attrs);
       attrs = NULL_TREE;
-      if (parm != NULL)
-	{
-	  good_parm = true;
-	  push_parm_decl (parm);
-	}
+      if (parm == NULL)
+	bad_parm = true;
+      else
+	push_parm_decl (parm);
       if (c_parser_next_token_is (parser, CPP_SEMICOLON))
 	{
 	  tree new_attrs;
@@ -2774,20 +2773,13 @@  c_parser_parms_list_declarator (c_parser
       if (c_parser_next_token_is (parser, CPP_CLOSE_PAREN))
 	{
 	  c_parser_consume_token (parser);
-	  if (good_parm)
-	    return get_parm_info (false);
-	  else
+	  if (bad_parm)
 	    {
-	      struct c_arg_info *ret
-		= XOBNEW (&parser_obstack, struct c_arg_info);
-	      ret->parms = 0;
-	      ret->tags = 0;
-	      ret->types = 0;
-	      ret->others = 0;
-	      ret->pending_sizes = 0;
-	      ret->had_vla_unspec = 0;
-	      return ret;
+	      get_pending_sizes ();
+	      return NULL;
 	    }
+	  else
+	    return get_parm_info (false);
 	}
       if (!c_parser_require (parser, CPP_COMMA,
 			     "expected %<;%>, %<,%> or %<)%>"))
@@ -2802,20 +2794,13 @@  c_parser_parms_list_declarator (c_parser
 	  if (c_parser_next_token_is (parser, CPP_CLOSE_PAREN))
 	    {
 	      c_parser_consume_token (parser);
-	      if (good_parm)
-		return get_parm_info (true);
-	      else
+	      if (bad_parm)
 		{
-		  struct c_arg_info *ret
-		    = XOBNEW (&parser_obstack, struct c_arg_info);
-		  ret->parms = 0;
-		  ret->tags = 0;
-		  ret->types = 0;
-		  ret->others = 0;
-		  ret->pending_sizes = 0;
-		  ret->had_vla_unspec = 0;
-		  return ret;
+		  get_pending_sizes ();
+		  return NULL;
 		}
+	      else
+		return get_parm_info (true);
 	    }
 	  else
 	    {
@@ -2841,10 +2826,22 @@  c_parser_parameter_declaration (c_parser
   bool dummy = false;
   if (!c_parser_next_token_starts_declspecs (parser))
     {
+      c_token *token = c_parser_peek_token (parser);
+      if (parser->error)
+	return NULL;
+      c_parser_set_source_position_from_token (token);
+      if (token->type == CPP_NAME
+	  && c_parser_peek_2nd_token (parser)->type != CPP_COMMA
+	  && c_parser_peek_2nd_token (parser)->type != CPP_CLOSE_PAREN)
+	{
+	  error ("unknown type name %qE", token->value);
+	  parser->error = true;
+	}
       /* ??? In some Objective-C cases '...' isn't applicable so there
 	 should be a different message.  */
-      c_parser_error (parser,
-		      "expected declaration specifiers or %<...%>");
+      else
+	c_parser_error (parser,
+			"expected declaration specifiers or %<...%>");
       c_parser_skip_to_end_of_parameter (parser);
       return NULL;
     }
Index: testsuite/gcc.dg/noncompile/pr44517.c
===================================================================
--- testsuite/gcc.dg/noncompile/pr44517.c	(revision 0)
+++ testsuite/gcc.dg/noncompile/pr44517.c	(revision 0)
@@ -0,0 +1,16 @@ 
+/* PR c/44517: Improve diagnostic for misspelled typename in function declaration. */
+int f1(int x, pid_t y, long z, in t) {  /* { dg-error "unknown type name 'pid_t'|unknown type name 'in'" } */
+  return x + y + z + t;
+}
+
+int f2(int x, lon y, long z, ...){ /* { dg-error "unknown type name 'lon'" } */
+  return;
+}
+
+void f3(int n, int a[n], pid_t x); /* { dg-error "unknown type name 'pid_t'" } */
+void f4() {}
+void f5(int a, *b); /* { dg-error "expected declaration specifiers or" } */
+void f6(int a, b);  /* { dg-error "expected declaration specifiers or" } */
+void f7(int a, goto b); /* { dg-error "expected declaration specifiers or" } */
+void f8(int a, in goto); /* { dg-error "unknown type name 'in'" } */
+void f9(int a, in 1); /* { dg-error "unknown type name 'in'" } */
Index: testsuite/gcc.dg/noncompile/990416-1.c
===================================================================
--- testsuite/gcc.dg/noncompile/990416-1.c	(revision 160889)
+++ testsuite/gcc.dg/noncompile/990416-1.c	(working copy)
@@ -2,11 +2,11 @@  extern void *memcpy (void *, const void 
 typedef int word_type;
    
 static void
-copy_reg (unsigned int reg, frame_state *udata,	/* { dg-error "parse|syntax|expected" } */
-	  frame_state *target_udata)	/* { dg-error "expected" } */
+copy_reg (unsigned int reg, frame_state *udata,	/* { dg-error "unknown type name" } */
+	  frame_state *target_udata)	/* { dg-error "unknown type name" } */
 {  
-  word_type *preg = get_reg_addr (reg, udata, 0);	/* { dg-error "undeclared|function|without a cast" } */
-  word_type *ptreg = get_reg_addr (reg, target_udata, 0); /* { dg-error "undeclared|without a cast" } */
+  word_type *preg = ge_reg_addr (reg, udata, 0);
+  word_type *ptreg = ge_reg_addr (reg, target_udata, 0);
    
   memcpy (ptreg, preg, __builtin_dwarf_reg_size (reg));
 }