Java source-level incompatibility for DataSource.map [161150011]

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Description

cc...@google.com

created issue #1

Jul 13, 2020 07:34PM

From internal report, seeing errors like the following:

 error: reference to map is ambiguous
          .map(
          ^
  both method <ToValue#1>map(Function<Value,ToValue#1>) in DataSource and method <ToValue#2>map(Function1<? super Value,? extends ToValue#2>) in DataSource match
  where ToValue#1,Value,Key,ToValue#2 are type-variables:
    ToValue#1 extends Object declared in method <ToValue#1>map(Function<Value,ToValue#1>)
    Value extends Object declared in class DataSource
    Key extends Object declared in class DataSource
    ToValue#2 extends Object declared in method <ToValue#2>map(Function1<? super Value,? extends ToValue#2>)

map is ambiguous with lambda syntax, due to having the same lambda signature for both variants.

Note - can't make it an extension in this case, since it's open (for legacy reasons).

Comments

cc...@google.com <cc...@google.com> Jul 13, 2020 07:34PM

Accepted by cc...@google.com.

ap...@google.com <ap...@google.com> #2Jul 13, 2020 08:54PM

Project: platform/frameworks/support
Branch: androidx-master-dev

commit bb6ed7ad0a041758b34bdc1ca671f1bb77a970f7
Author: Chris Craik <ccraik@google.com>
Date: Mon Jul 13 12:31:34 2020

Use @JvmSynthetic to preserve map source compat

Bug: 161150011
Test: ./gradlew paging:p-c:test paging:p-ru:cC paging:p-rx:cC paging:p-g:cC
Relnote: "Hid DataSource kotlin map function variants from Java, to
resolve ambiguity between original and kotlin variants."

Change-Id: If7b239bfd58391e11b46a4fcd2ea99ffd729f84d

M paging/common/api/3.0.0-alpha03.txt
M paging/common/api/current.txt
M paging/common/api/public_plus_experimental_3.0.0-alpha03.txt
M paging/common/api/public_plus_experimental_current.txt
M paging/common/api/restricted_3.0.0-alpha03.txt
M paging/common/api/restricted_current.txt
M paging/common/src/main/kotlin/androidx/paging/DataSource.kt

https://android-review.googlesource.com/1361143

cc...@google.com <cc...@google.com> Jul 13, 2020 08:54PM

Marked as fixed.

Issue 161150011

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cc...@google.com <cc...@google.com> Jul 13, 2020 07:34PM

ap...@google.com <ap...@google.com> #2Jul 13, 2020 08:54PM

cc...@google.com <cc...@google.com> Jul 13, 2020 08:54PM

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