RFR: 8288589: Files.readString ignores encoding errors for UTF-16 [v6]

[Alan Bateman]

On Wed, 22 Jun 2022 17:46:58 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> This is a regression caused by the fix to [JDK-8286287](https://bugs.openjdk.org/browse/JDK-8286287), which assumed the method `String.decodeWithDecoder()` was only invoked with cs.REPLACE mode based on the comment "should not happen". Possibly this refers to the `String(byte[], int, int, Charset)` constructor, which specifically mentions the `REPLACE` mode. However, the method is invoked with `String.newStringNoRepl()` and it should NOT replace the malformed input (duh!). The fix is to throw an `Error` for the former case as before the regression, and `CharacterCodingException` for the latter via an `IllegalArgumentException`.
>> In fact, `Files.readString()` stopped throwing a `MalformedInputException` since JDK17 with the fix to JDK-8259842, which started throwing an `Error`.
>
> Naoto Sato has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
> 
>  - Leave the log files in the current directory
>  - Merge branch 'master' into JDK-8288589
>  - Moved `@Test` annotations
>  - Refined the test, adding more variations.
>  - Adding a test case in ReadWriteString.java
>  - Added c2b test
>  - 8288589: Files.readString ignores encoding errors for UTF-16

Marked as reviewed by alanb (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/9193