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* Re: c/9166: [2003-01-03] C front end's type scoping not right
@ 2003-01-04 11:26 Joseph S. Myers
0 siblings, 0 replies; 5+ messages in thread
From: Joseph S. Myers @ 2003-01-04 11:26 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c/9166; it has been noted by GNATS.
From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: <neil@gcc.gnu.org>
Cc: <gcc-gnats@gcc.gnu.org>, <gcc-bugs@gcc.gnu.org>
Subject: Re: c/9166: [2003-01-03] C front end's type scoping not right
Date: Sat, 4 Jan 2003 11:24:42 +0000 (GMT)
On 4 Jan 2003 neil@gcc.gnu.org wrote:
> /* Compile the code snippet below with -pedantic. The code is illegal
> because the function f is redeclared with an incompatible prototype,
> but GCC doesn't winge. */
>
> struct bar {int x, y;};
>
> void foo ()
> {
> extern void f( struct bar {double x, y;} );
> }
>
> void f (struct bar );
What makes you think the former prototype is visible at the latter? The
former declaration has block scope; as the Rationale discusses, there is a
delibrate compromise in the standard here, where a former block scope
external declaration can be considered, but need not be. Incompatible
declarations need only be diagnosed in the same scope (by 6.7#4).
Declarations refering to the same object or function that are not in the
same scope merely yield undefined behavior if of incompatible types
(6.2.7#2). That said, a mandatory pedwarn for a latter declaration
incompatible with a former invisible declaration would make sense, but
there is no bug here and the former declaration shouldn't be considered
visible for most ordinary purposes (seeing whether the function is
declared when it is used, converting arguments, etc.) - just to complain
about the incompatibility with another declaration.
--
Joseph S. Myers
jsm28@cam.ac.uk
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: c/9166: [2003-01-03] C front end's type scoping not right
@ 2003-03-01 8:37 neil
0 siblings, 0 replies; 5+ messages in thread
From: neil @ 2003-03-01 8:37 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, neil, nobody
Synopsis: [2003-01-03] C front end's type scoping not right
State-Changed-From-To: analyzed->closed
State-Changed-By: neil
State-Changed-When: Sat Mar 1 08:37:01 2003
State-Changed-Why:
Submitter no longer considers this important.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9166
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: c/9166: [2003-01-03] C front end's type scoping not right
@ 2003-01-08 1:03 bangerth
0 siblings, 0 replies; 5+ messages in thread
From: bangerth @ 2003-01-08 1:03 UTC (permalink / raw)
To: gcc-bugs, gcc-prs, neil, nobody
Synopsis: [2003-01-03] C front end's type scoping not right
State-Changed-From-To: open->analyzed
State-Changed-By: bangerth
State-Changed-When: Tue Jan 7 17:03:54 2003
State-Changed-Why:
This has been analyzed before. For completeness, here's what
icc7 says:
tmp/g> /home/bangerth/bin/gcc-3.4-pre/bin/gcc -std=c99 -c -pedantic x.c
x.c: In function `foo':
x.c:5: warning: `struct bar' declared inside parameter list
x.c:5: warning: its scope is only this definition or declaration, which is probably not what you want
tmp/g> icc x.c
x.c(5): warning #274: declaration is not visible outside of function
extern void f( struct bar {double x, y;} );
^
x.c(8): warning #159: declaration is incompatible with previous "f" (declared at line 5)
void f (struct bar );
^
From the discussion, this should really be a change-request
than a bug report.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9166
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: c/9166: [2003-01-03] C front end's type scoping not right
@ 2003-01-04 13:36 Neil Booth
0 siblings, 0 replies; 5+ messages in thread
From: Neil Booth @ 2003-01-04 13:36 UTC (permalink / raw)
To: nobody; +Cc: gcc-prs
The following reply was made to PR c/9166; it has been noted by GNATS.
From: Neil Booth <neil@daikokuya.co.uk>
To: "Joseph S. Myers" <jsm28@cam.ac.uk>
Cc: neil@gcc.gnu.org, gcc-gnats@gcc.gnu.org, gcc-bugs@gcc.gnu.org
Subject: Re: c/9166: [2003-01-03] C front end's type scoping not right
Date: Sat, 4 Jan 2003 13:27:10 +0000
Joseph S. Myers wrote:-
> What makes you think the former prototype is visible at the latter? The
> former declaration has block scope; as the Rationale discusses, there is a
> delibrate compromise in the standard here, where a former block scope
> external declaration can be considered, but need not be. Incompatible
> declarations need only be diagnosed in the same scope (by 6.7#4).
> Declarations refering to the same object or function that are not in the
> same scope merely yield undefined behavior if of incompatible types
> (6.2.7#2).
Fair enough. Obviously I'd never considered the former declaration
visible, it clearly isn't. I'd just not read the consequences of
incompatible declarations closely enough.
I think a pedwarn would be nice, though I suspect it's hard with GCC's
current code.
At least the behaviour is better than EDG and LCC, which always reject the
second declaration as incompatible even when it's identical.
Neil.
^ permalink raw reply [flat|nested] 5+ messages in thread
* c/9166: [2003-01-03] C front end's type scoping not right
@ 2003-01-04 0:36 neil
0 siblings, 0 replies; 5+ messages in thread
From: neil @ 2003-01-04 0:36 UTC (permalink / raw)
To: gcc-gnats
>Number: 9166
>Category: c
>Synopsis: [2003-01-03] C front end's type scoping not right
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Fri Jan 03 16:36:00 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: neil@gcc.gnu.org
>Release: GCC 3.4 and earlier
>Organization:
>Environment:
>Description:
/* Compile the code snippet below with -pedantic. The code
is illegal because the function f is redeclared with an incompatible prototype, but GCC doesn't winge. */
struct bar {int x, y;};
void foo ()
{
extern void f( struct bar {double x, y;} );
}
void f (struct bar );
>How-To-Repeat:
>Fix:
I doubt it's easy with the current code. Best idea is to clean up the front-end's handling of scopes; it's too messy and obfuscated.
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 5+ messages in thread
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2003-01-04 11:26 c/9166: [2003-01-03] C front end's type scoping not right Joseph S. Myers
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2003-03-01 8:37 neil
2003-01-08 1:03 bangerth
2003-01-04 13:36 Neil Booth
2003-01-04 0:36 neil
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