Qt 6.9: Return type for QObjectData_dynamicMetaObject is now const #195
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rcalixte
commented
Apr 10, 2025
rcalixte
commented
- Closes Qt 6.9 not compiling - QObjectData_dynamicMetaObject invalid conversion from const #194
…taObject for Qt 6.9+
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The macro is copied but shouldn't represent a licensing issue. I added the comment so that it would be clear. Feel free to modify it as needed. |
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Thanks for the quick PR! LGTM 🚢 |
| @@ -36,7 +36,13 @@ void miqt_exec_callback_QObject_disconnectNotify(QObject*, intptr_t, QMetaMethod | |||
| } /* extern C */ | |||
| #endif | |||
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| // This method's return type was changed from non-const to const in Qt 6.9 | |||
| #if QT_VERSION >= QT_VERSION_CHECK(6,9,0) | |||
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can technically return the const pointer for all qt versions
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Isn't this a type mismatch if the underlying type isn't const? And couldn't it lead to undefined behavior on Qt versions under 6.9?
Ultimately, this is a stop-gap of sorts. Once we start building on a version at or above Qt 6.9, the patches in config-allowlist.go can go away. (It probably makes sense to leave the remaining code... just in case. 😅)
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Once we start building
An interesting approach would actually be to generate the bindings for each qt version separately and use the #if trick for any "new" features - ie one would start with 6.0 generating all of that, then gradually add each version as it happens, hidden behind #if - then the mappings could / would work with any qt version that the user happens to have installed.
Isn't this a type mismatch
you can assign a non-const pointer to a const pointer of the same underlying type without issue, in general - the other direction is not allowed though.
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As well as running genbindings on every version of Qt and diffing/merging the results, the other step would be to run it for clang-linux, clang-mingw, and clang-osxcross to identify all the cross-platform functions (#59).
