869679 - Create const versions of nsSVGElement::GetXYZInfo methods (so we can invoke those methods from other const accessors)

Status: NEW

(Core :: SVG, defect)

Description

[Daniel Holbert [:dholbert]]

I *think* nsSVGElement::GetLengthInfo, etc. can be made into const methods.

Filing this bug on doing that.

I'm making this depend on bug 869668, which marks these methods as MOZ_OVERRIDE so that we won't accidentally orphan one of them when changing the base class's method-signature.

Comment 1

[Daniel Holbert [:dholbert]]

er, never mind -- For GetLengthInfo to be usefully const, its "mLengths" array would need to be const as well (since that's generally a pointer to an array on |this|).  And while many of the GetLengthInfo accesses are read-only, there are also some that involve writes to |mLengths|.

For example, nsSVGElement::ParseAttribute() has:
>  LengthAttributesInfo lengthInfo = GetLengthInfo();
[...]
>  rv = lengthInfo.mLengths[i].SetBaseValueString(aValue, this, false);

(and SetBaseValueString is a non-const method)

So: the correct, more workable (but slightly more clumsy) version of this bug is: we could *create* const versions of GetLengthInfo() & friends, alongside the existing mutable versions.

Comment 2

[Robert Longson [:longsonr]]

I imagine the easy way to fix this is to wait for C++23 deducing this: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p0847r7.html