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* [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
@ 2021-12-06 14:18 shlomo at fastmail dot com
2021-12-06 14:30 ` [Bug c++/103583] " redi at gcc dot gnu.org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: shlomo at fastmail dot com @ 2021-12-06 14:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
Bug ID: 103583
Summary: Range loop: "error: 'begin' was not declared in this
scope" when 'end' is missing
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: shlomo at fastmail dot com
Target Milestone: ---
Compiling the following with gcc -c:
struct A {
int *begin();
// int *end();
};
void foo(A a) {
for (auto it : a) { }
}
shows two error messages:
error: ‘begin’ was not declared in this scope
error: ‘end’ was not declared in this scope
The first error message is incorrect.
If only one of 'begin' and 'end' is missing, GCC shouldn't print an error about
the other one.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/103583] Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
@ 2021-12-06 14:30 ` redi at gcc dot gnu.org
2021-12-06 14:31 ` redi at gcc dot gnu.org
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2021-12-06 14:30 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The error is technically correct.
If your class had both begin and end, then the range-based for loop would use
a.begin() and a.end(). But because it doesn't have both, the loop uses begin(a)
and end(a), neither of which is defined. And that's what the error says.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/103583] Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
2021-12-06 14:30 ` [Bug c++/103583] " redi at gcc dot gnu.org
@ 2021-12-06 14:31 ` redi at gcc dot gnu.org
2021-12-06 14:35 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2021-12-06 14:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
See [stmt.ranged] p1.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/103583] Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
2021-12-06 14:30 ` [Bug c++/103583] " redi at gcc dot gnu.org
2021-12-06 14:31 ` redi at gcc dot gnu.org
@ 2021-12-06 14:35 ` redi at gcc dot gnu.org
2021-12-06 21:59 ` pinskia at gcc dot gnu.org
2022-01-06 9:06 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2021-12-06 14:35 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think the implementation doesn't do anything special to handle this case. It
just looks for the members a.begin() and a.end() and then if they aren't found,
it goes ahead with rewriting the code to use begin(a) and end(a), and any
errors that result from that are shown straight to the user.
Another option would be to do lookup for begin(a) and end(a) with errors
suppressed, and if they aren't found, issue a custom diagnostic saying
something like "no suitable begin/end pair available for range-based 'for'
loop".
Clang seems to do something similar:
f.C:6:18: error: invalid range expression of type 'A'; no viable 'end' function
available
for (auto it : a) { }
^ ~
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/103583] Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
` (2 preceding siblings ...)
2021-12-06 14:35 ` redi at gcc dot gnu.org
@ 2021-12-06 21:59 ` pinskia at gcc dot gnu.org
2022-01-06 9:06 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-06 21:59 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2021-12-06
Severity|normal |enhancement
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #3)
> Another option would be to do lookup for begin(a) and end(a) with errors
> suppressed, and if they aren't found, issue a custom diagnostic saying
> something like "no suitable begin/end pair available for range-based 'for'
> loop".
I think this is a good option.
Confirmed.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug c++/103583] Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing
2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
` (3 preceding siblings ...)
2021-12-06 21:59 ` pinskia at gcc dot gnu.org
@ 2022-01-06 9:06 ` redi at gcc dot gnu.org
4 siblings, 0 replies; 6+ messages in thread
From: redi at gcc dot gnu.org @ 2022-01-06 9:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103583
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|NEW |RESOLVED
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
dup
*** This bug has been marked as a duplicate of bug 82125 ***
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-01-06 9:06 UTC | newest]
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2021-12-06 14:18 [Bug c++/103583] New: Range loop: "error: 'begin' was not declared in this scope" when 'end' is missing shlomo at fastmail dot com
2021-12-06 14:30 ` [Bug c++/103583] " redi at gcc dot gnu.org
2021-12-06 14:31 ` redi at gcc dot gnu.org
2021-12-06 14:35 ` redi at gcc dot gnu.org
2021-12-06 21:59 ` pinskia at gcc dot gnu.org
2022-01-06 9:06 ` redi at gcc dot gnu.org
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