RFR: 8356152: String.concat can throw StringIndexOutOfBoundsException [v4]

[Andrey Turbanov]

On Mon, 5 May 2025 14:38:05 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> A fix to throw `OutOfMemoryError`, as done in releases ≤ 23.
>
> Raffaello Giulietti has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Added language concat + to test.

test/jdk/java/lang/String/concat/HugeConcatTest.java line 38:

> 36: import static org.junit.Assert.assertThrows;
> 37: 
> 38: public class HugeConcatTest {

I've tried to execute the test with reverting changes in `StringConcatHelper` - it doesn't fail.
Added logging and actually OOM happened due to heap size:

Reall got OOM: java.lang.OutOfMemoryError: Overflow: String length out of range
Reall got OOM: java.lang.OutOfMemoryError: Overflow: String length out of range
Reall got OOM: java.lang.OutOfMemoryError: Java heap space
Reall got OOM: java.lang.OutOfMemoryError: Java heap space
Reall got OOM: java.lang.OutOfMemoryError: Java heap space
Reall got OOM: java.lang.OutOfMemoryError: Java heap space
Reall got OOM: java.lang.OutOfMemoryError: Overflow: String length out of range
Reall got OOM: java.lang.OutOfMemoryError: Overflow: String length out of range
----------System.err:(13/854)----------
STARTED    HugeConcatTest::testConcat_UTF16_UTF16 'testConcat_UTF16_UTF16()'
SUCCESSFUL HugeConcatTest::testConcat_UTF16_UTF16 'testConcat_UTF16_UTF16()' [9ms]
STARTED    HugeConcatTest::testConcat_Latin1_UTF16 'testConcat_Latin1_UTF16()'
SUCCESSFUL HugeConcatTest::testConcat_Latin1_UTF16 'testConcat_Latin1_UTF16()' [657ms]
STARTED    HugeConcatTest::testConcat_UTF16_Latin1 'testConcat_UTF16_Latin1()'
SUCCESSFUL HugeConcatTest::testConcat_UTF16_Latin1 'testConcat_UTF16_Latin1()' [52ms]
STARTED    HugeConcatTest::testConcat_Latin1_Latin1 'testConcat_Latin1_Latin1()'
SUCCESSFUL HugeConcatTest::testConcat_Latin1_Latin1 'testConcat_Latin1_Latin1()' [1ms]


I think we should validate error message too. Not only fact that it was thrown.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25038#discussion_r2073833500