[Bug c/64526] New: No warning on function call with excessive arguments

[Bug c/64526] New: No warning on function call with excessive arguments

[chengniansun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64526

            Bug ID: 64526
           Summary: No warning on function call with excessive arguments
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com

GCC does not warn on the following function call to "fn1". The function "fn1"
is defined with no parameters. Based on the standard, the empty parameter list
in a function declarator that is part of a definition of that function
specifies that the function has no parameters. 


$ cat test.c

void fn1 () {}

void fn2 (int p) {  fn1 (p); }

$ gcc-trunk -Wall -Wextra -pedantic -std=c11 -c test.c

$ clang-trunk -c test.c

test.c:2:27: warning: too many arguments in call to 'fn1'

void fn2 (int p) {  fn1 (p); }

                    ~~~   ^

1 warning generated.

$

[Bug c/64526] No warning on function call with excessive arguments

[rth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64526

Richard Henderson <rth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
                 CC|                            |rth at gcc dot gnu.org
         Resolution|---                         |INVALID

--- Comment #1 from Richard Henderson <rth at gcc dot gnu.org> ---
Not a bug -- fn1 is not a function with no arguments,
but an unprototyped function.  To get a function with
no arguments you must write

void fn1 (void) {}

This is C, not C++.

[Bug c/64526] No warning on function call with excessive arguments

[chengniansun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64526

Chengnian Sun <chengniansun at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |---

--- Comment #2 from Chengnian Sun <chengniansun at gmail dot com> ---
(In reply to Richard Henderson from comment #1)
> Not a bug -- fn1 is not a function with no arguments,
> but an unprototyped function.  To get a function with
> no arguments you must write
> 
> void fn1 (void) {}
> 
> This is C, not C++.


Thanks for your reply. But I am still puzzled by a paragraph in the standard
(http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf):

-------------- C11 standard, sec 6.7.6.3, page 134 --------------
14. An identifier list declares only the identifiers of the parameters 
of the function. An empty list in a function declarator that is part of 
a definition of that function specifies that the function has no 
parameters. The empty list in a function declarator that is not part of 
a definition of that function specifies that no information about 
the number or types of the parameters is supplied.
------------------------- END -----------------------------------


So if I understand it correctly, the function "fn1" does not have any
parameters. Please kindly advise. Thanks.

[Bug c/64526] No warning on function call with excessive arguments

[rth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64526

Richard Henderson <rth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #4 from Richard Henderson <rth at gcc dot gnu.org> ---
Still invalid.

[Bug c/64526] No warning on function call with excessive arguments

[chengniansun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64526

--- Comment #5 from Chengnian Sun <chengniansun at gmail dot com> ---
(In reply to joseph@codesourcery.com from comment #3)
> "has no parameters" does not mean "has a type that includes a prototype 
> with no parameters".  See DR#317.
> 
> http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_317.htm

Thanks for your pointer. 

But from the perspective of diagnostics, I believe it is worthy to emit a
warning on this case, as the execution of the function call is undefined
according to the standard.