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* [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax
@ 2012-08-17 15:26 drepper.fsp at gmail dot com
2012-08-17 15:40 ` [Bug middle-end/54299] " redi at gcc dot gnu.org
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: drepper.fsp at gmail dot com @ 2012-08-17 15:26 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299
Bug #: 54299
Summary: Array parameter does not allow for iterator syntax
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: drepper.fsp@gmail.com
Compile the following code:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int aa[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int f(int arr[10])
{
int s = 0;
for (auto i : arr)
s += i;
return s;
}
int main()
{
return f(aa);
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This fails with
u.cc: In function ‘int f(int*)’:
u.cc:18:17: error: ‘begin’ was not declared in this scope
u.cc:18:17: error: ‘end’ was not declared in this scope
u.cc:18:17: error: unable to deduce ‘auto’ from ‘<expression error>’
This indicates that the problem is that the parameter is seen as 'int *'
instead of as 'int [10]'. According to Andrew another problem caused by the
too-early decay of arguments to pointers (bug 24666).
Changing the code as follows makes it compile:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
int aa[1][10] = { { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 } };
int f(int arr[1][10])
{
int s = 0;
for (auto i : arr[0])
s += i;
return s;
}
int main()
{
return f(aa);
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/54299] Array parameter does not allow for iterator syntax
2012-08-17 15:26 [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax drepper.fsp at gmail dot com
@ 2012-08-17 15:40 ` redi at gcc dot gnu.org
2012-08-17 15:43 ` redi at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: redi at gcc dot gnu.org @ 2012-08-17 15:40 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-08-17 15:40:42 UTC ---
I think the compiler's correct to reject the first example, the type of arr is
int* so it's not an array, and so the for loop calls begin(arr) and end(arr)
In the second example the parameter type is int(*)[10] so arr[0] is an array of
known bound, and so the for loop works.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug middle-end/54299] Array parameter does not allow for iterator syntax
2012-08-17 15:26 [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax drepper.fsp at gmail dot com
2012-08-17 15:40 ` [Bug middle-end/54299] " redi at gcc dot gnu.org
@ 2012-08-17 15:43 ` redi at gcc dot gnu.org
2022-01-06 3:44 ` [Bug c++/54299] " pinskia at gcc dot gnu.org
2022-01-06 3:46 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: redi at gcc dot gnu.org @ 2012-08-17 15:43 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-08-17 15:43:02 UTC ---
It would be nice if G++ told you the type of the range, as Clang++ does:
a.cc:9:15: error: use of undeclared identifier 'begin'
for (auto i : arr)
^
a.cc:9:15: note: range has type 'int *'
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54299] Array parameter does not allow for iterator syntax
2012-08-17 15:26 [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax drepper.fsp at gmail dot com
2012-08-17 15:40 ` [Bug middle-end/54299] " redi at gcc dot gnu.org
2012-08-17 15:43 ` redi at gcc dot gnu.org
@ 2022-01-06 3:44 ` pinskia at gcc dot gnu.org
2022-01-06 3:46 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-01-06 3:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-01-06
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Clang gives even better diagnostic now:
<source>:7:17: error: cannot build range expression with array function
parameter 'arr' since parameter with array type 'int[10]' is treated as pointer
type 'int *'
for (auto i : arr)
^~~
<source>:4:11: note: declared here
int f(int arr[10])
^
GCC trunk gives:
<source>: In function 'int f(int*)':
<source>:7:17: error: 'begin' was not declared in this scope
7 | for (auto i : arr)
| ^~~
<source>:7:17: error: 'end' was not declared in this scope
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/54299] Array parameter does not allow for iterator syntax
2012-08-17 15:26 [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax drepper.fsp at gmail dot com
` (2 preceding siblings ...)
2022-01-06 3:44 ` [Bug c++/54299] " pinskia at gcc dot gnu.org
@ 2022-01-06 3:46 ` pinskia at gcc dot gnu.org
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-01-06 3:46 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54299
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|normal |enhancement
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-01-06 3:46 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2012-08-17 15:26 [Bug middle-end/54299] New: Array parameter does not allow for iterator syntax drepper.fsp at gmail dot com
2012-08-17 15:40 ` [Bug middle-end/54299] " redi at gcc dot gnu.org
2012-08-17 15:43 ` redi at gcc dot gnu.org
2022-01-06 3:44 ` [Bug c++/54299] " pinskia at gcc dot gnu.org
2022-01-06 3:46 ` pinskia at gcc dot gnu.org
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