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fix: correctly require a ClassTag when building a multidimensional Array #23902

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Merged
merged 1 commit into from
Sep 12, 2025
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fix: correctly require a ClassTag when building a multidimensional Array #23902

merged 1 commit into from
Sep 12, 2025

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hamzaremmal
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Closes #23901

@hamzaremmal hamzaremmal requested a review from sjrd September 11, 2025 13:38
sjrd
sjrd reviewed Sep 11, 2025
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@hamzaremmal hamzaremmal requested a review from sjrd September 11, 2025 15:30
hamzaremmal
hamzaremmal commented Sep 11, 2025
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@sjrd sjrd disabled auto-merge September 12, 2025 09:42
sjrd
sjrd approved these changes Sep 12, 2025
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LGTM after giving a better name to isGenericArray.

bishabosha
bishabosha reviewed Sep 12, 2025
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tests/run/i23901.scala

@main def Test =
val arr: Array[Array[String]] = MyArray.empty[String]
assert(arr.length == 0)
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maybe test the runtime class?

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What do you mean?

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well to assert that it is specialised based on the classtag

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Before this fix, we couldn't even create the array in Line 7, this is a run test witnessing that we are indeed creating the array correctly. Also, dotty will add a call to asInstanceOf[Array[Array[String]]] here which is enough to assert that the right array is created. Also note that asInstanceOf was what indicated that something was really wrong it the generated code.

@hamzaremmal hamzaremmal merged commit e227128 into scala:main Sep 12, 2025
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@hamzaremmal hamzaremmal deleted the i23901 branch September 12, 2025 12:24
@WojciechMazur WojciechMazur mentioned this pull request Sep 20, 2025
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WojciechMazur added a commit that referenced this pull request Sep 22, 2025
@WojciechMazur
Backport "fix: correctly require a ClassTag when building a multidi…
e5d05b5 
…mensional `Array`" to 3.7.4 (#24000)

Backports #23902 to the 3.7.4.

PR submitted by the release tooling.
[skip ci]
@WojciechMazur WojciechMazur added this to the 3.7.4 milestone Sep 23, 2025
@tgodzik tgodzik mentioned this pull request Sep 26, 2025
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Successfully merging this pull request may close these issues.

Wrong code emitted when creating generic multidimensional arrays
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@hamzaremmal @sjrd @bishabosha @WojciechMazur