On Jan 5, 2026, at 21:24, Peter Eisentraut <[email protected]> wrote:
On 30.12.25 10:03, Chao Li wrote:
Thanks a lot for pointing out the error. v3 has reverted the changes to be
the same as v1 and rebased.
The explanation of this patch doesn't seem right. The commit message says
"... eliminate cast-away-const ...", but that is not what is happening in
the code. For example, in
static int
DOTypeNameCompare(const void *p1, const void *p2)
{
- DumpableObject *obj1 = *(DumpableObject *const *) p1;
- DumpableObject *obj2 = *(DumpableObject *const *) p2;
+ const DumpableObject *obj1 = *(DumpableObject *const *) p1;
+ const DumpableObject *obj2 = *(DumpableObject *const *) p2;
p1 is of type pointer-to-const-void, which is then cast into
pointer-to-const-pointer-to-DumpableObject (which preserves the qualifier,
because it's pointer-to-const-xxx on both sides), which is then
dereferenced to result in type const-pointer-to-DumpableObject (type
DumpableObject * const, not const DumpableObject *), which is then assigned
by value to obj1 of type pointer-to-DumpableObject. This is all entirely
correct.
Now there is nothing wrong with making the receiving obj1 have an
additional const qualification, if that's the promise you want to make
about it for that scope. But that's separate from preserving the qualifier
on p1. And it's incorrect to claim that this is fixing an existing
cast-away-const issue.
Thanks for the explanation, you’re right.
The original p1/p2 are pointers to pointers, and the const qualifier only
applies to the outer pointer. After dereferencing, the second-level pointer
(DumpableObject *) is obtained, and my change simply adds const
qualification to that pointer.
So this is not fixing a cast-away-const issue, but rather tightening the
const qualification of the local variables.
Independent of that, there appears to be some not quite finished code here:
- AttrDefInfo *adobj1 = *(AttrDefInfo *const *) p1;
- AttrDefInfo *adobj2 = *(AttrDefInfo *const *) p2;
+ const AttrDefInfo *adobj1 = p1;//*(AttrDefInfo *const *) p1;
+ const AttrDefInfo *adobj2 = *(AttrDefInfo *const *) p2;
Sorry for the dirty patch file of v3. I was doing some tests, and missed to
revert the dirty change.
V4 has updated the commit message and fixed the dirty code.
Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/
v4-0001-Use-const-qualified-local-pointers-in-DOTypeNameC.patch
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