http://d.puremagic.com/issues/show_bug.cgi?id=2632
Summary: Setting length on invalid arrays causes assertion
failure with a debug runtime
Product: D
Version: 1.039
Platform: All
OS/Version: All
Status: NEW
Severity: major
Priority: P2
Component: Phobos
AssignedTo: [email protected]
ReportedBy: [email protected]
Both of the below test cases work unless compiled against a debug runtime.
Test case 1:
void main() {
int[] a = (cast(int*)null)[0..1];
a.length = 1;
assert (a.length == 1);
assert (a[0] == 0);
}
Test case 2:
union Union {
int i;
ubyte[] a;
}
void main() {
Union u;
u.i = 10;
u.a.length = 1;
assert (u.a.length == 1);
assert (u.a[0] == 1);
}
The problematic assertion is assert(!p.length || p.data). It occurs in three
functions:
- _d_delarray
- _d_arraysetlengthT
- _d_arraysetlengthiT
The second one of the above is triggered by the given test cases. It'd be easy
to come up with ones that trigger the other two as well.
This behaviour doesn't seem to be specified, so I'm not completely sure whether
this should be fixed or not. I have two arguments in favour of removing the
assertions:
1. They're only sanity checks: they don't actually matter for behaviour. Code
which trips the asserts on a debug runtime runs fine on a release runtime.
Nothing actually expects the assertions to succeed.
2. Code which relies on such behaviour actually exists: test case 2 was reduced
from tango.text.Regex.
In Phobos, the functions are in phobos/internal/gc/gc.d; in Tango, they can be
found in tango/lib/compiler/{dmd,gdc}/lifetime.d; in LDC, they're in
runtime/internal/lifetime.d. This issue affects all of them.
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