[Development] Unnecessary ambiguity in Qt documentation about reentrancy and safety of const methods.

[Giuseppe D'Angelo]

On 19/07/2026 00:38, NIkolai Marchenko wrote:
> I am not exactly sure if your wording covers the 
> qlocale::toDouble(string,bool&) or not.  aka non const but also 
> partially not same data.


Well, the signature is

> double QLocale::toDouble(const QString &s, bool *ok = nullptr) const

Therefore, in the extended contract, it's OK to call this function from 
multiple threads, without synchronization, on the same QLocale object 
and/or on the same QString object. It's not OK to call it on the same 
bool object.

Without the extended contract, do note that it's formally illegal to 
call this function on the same QString instance, even if called on 
different QLocale instances. toDouble() could call something like 
`s.utf16()` internally, which isn't thread-safe.

My 2 c,
-- 
Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
KDAB (France) S.A.S., a KDAB Group company
Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
KDAB - Trusted Software Excellence
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