path: root/tests/auto/testlib/selftests
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authorGiuseppe D'Angelo <>2022-11-04 02:58:51 +0100
committerGiuseppe D'Angelo <>2022-12-09 16:29:11 +0100
commit9e75a4cca3e4ef55d6d1c6b7dddd8565e3b412d0 (patch)
treedd5a5812a85bda06f4b966fe2d886b37851f09c2 /tests/auto/testlib/selftests
parent6294ee060eeb564d7fce3eb56624b0711d30af15 (diff)
QDomDocument: ensure a defined order of attributes when savingHEADdev
XML does not impose any semantics based on the order of the attributes; they're an unordered set. Quoting [1]: > Note that the order of attribute specifications in a start-tag or empty-element tag is not significant and [2] 2.2.5: > An unordered set of attribute information items Still, using a QHash-based implementation to store attributes is annoying, because one cannot serialize the document in a stable way. The order of attributes is going to depend on the QString hash function (which we can change at any time) and the QHash seed (which is random and changes at every run). In other words, saving the same DOM will yield non deterministic outputs. That's annoying for testing, reproducible builds, and so on. Switching to an _ordered_ associative container for storing attributes won't, on its own, ensure any specific ordering. That's because: * attributes are currently kept associated using their name as the key, ignoring an eventual namespace prefix; * there's some convoluted logic that sometimes emits attributes in the xmlns namespace (to qualify a prefix). Hence, just go for the straightforward implementation and sort the attributes before streaming them. In the main loop I could have used a range-based for loop over the associative container used for attributes; since it's a Qt container, it would have yielded just the values in the map, and we are not interested into the keys. However I'm preparing for further changes down the road, so I'm opting for key/value iteration. I'm deliberately not offering an opt-out because: * I don't think this is so expensive to justify an opt-out; * I'm going to remove QHash anyways in a follow up commit. [1] [2] Task-number: QTBUG-76800 Task-number: QTBUG-25071 Change-Id: I6282ae2ccbee9c0099f138de48b94bb7c40b3680 Reviewed-by: Volker Hilsheimer <>
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