When compiling using gcc with, the below code will compile without any sort of error:


int foo (int)
{
     return 5;
}


Can the compilation result differ if I specify a name for the argument?

I can't see any way the naming of the parameter would ever make a difference in the actual compilation result.  The question arose because I noticed when compiling the following C program:


// Compile: gcc --std=c99 -c -pedantic -Wall -O3 foo.c
int foo (int)
{
     return 5;
}


The error: 'parameter name omitted' is output by the compiler.

Is there any non-obvious significance in the parameter name with C++11 or C99?


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On 08/30/2012 12:36 PM, andrew.gottemoller@debesys.net wrote:
>
> When compiling using gcc with, the below code will compile without any sort of error:
>
>
> int foo (int)
> {
>      return 5;
> }
>
>
> Can the compilation result differ if I specify a name for the argument?
>
> I can't see any way the naming of the parameter would ever make a difference in the actual compilation result.  The question arose because I noticed when compiling the following C program:
>
>
> // Compile: gcc --std=c99 -c -pedantic -Wall -O3 foo.c
> int foo (int)
> {
>      return 5;
> }
>
>
> The error: 'parameter name omitted' is output by the compiler.
>
> Is there any non-obvious significance in the parameter name with C++11 or C99?

In n1570 (which is very close to C2011) 6.9.1p5 is a constraint applying
to function definitions: "If the declarator includes a parameter type
list, the declaration of each parameter shall include an identifier,
except for the special case of a parameter list consisting of a single
parameter of type void, in which case there shall not be an identifier.
..." The C99 wording was identical.
6.9.1p6 says equivalent things about K&R style function declarations,
which are still allowed.

I could find no comparable wording in the C++ standard, so this may not
be true of C++11.


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[2nd attempt after 4 days]

On 30.08.2012 18:36, andrew.gottemoller@debesys.net wrote:
>
>  When compiling using gcc with, the below code will compile without
any sort of error:

What is "compiling using gcc with," supposed to mean?

>  int foo (int)
>  {
>        return 5;
>  }
>
>  Can the compilation result differ if I specify a name for the argument?

Not in this case. Of-course introducing a parameter name could have an
effect in other cases e.g. via name-hiding. Consider

int bla(){ return 5; }

int foo(int)
{
   return bla();
}

Assume now that we introduce the parameter name 'bla' here, this will
make the existing code ill-formed.

>  I can't see any way the naming of the parameter would ever make a
difference in the actual compilation result.  The question arose because
I noticed when compiling the following C program:
>
>
>  // Compile: gcc --std=c99 -c -pedantic -Wall -O3 foo.c
>  int foo (int)
>  {
>        return 5;
>  }
>
>
>  The error: 'parameter name omitted' is output by the compiler.
>
>  Is there any non-obvious significance in the parameter name with
C++11 or C99?

Yes, there is. In C99 (I have no older C standard available for further
reference) we find in 6.9.1 p5:

"If the declarator includes a parameter type list, the declaration of
each parameter shall include an identifier, except for the special case
of a parameter list consisting of a single parameter of type void, in
which case there shall not be an identifier."

In other words: The above function definition is ill-formed in C99, but
not in C++ (Note that for non-defining function declarations this
restriction does not exists).

HTH&  Greetings from Bremen,

Daniel Kr   gler


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On 09/05/2012 02:24 PM, Daniel Kr=FCgler wrote:
> [2nd attempt after 4 days]
>
> On 30.08.2012 18:36, andrew.gottemoller@debesys.net wrote:
>>
>>  When compiling using gcc with, the below code will compile without
> any sort of error:
>
> What is "compiling using gcc with," supposed to mean?

Presumably , he meant either "compiling using gcc" or "compiling with
gcc", both of which mean pretty much the same thing.



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