8312976: MatchResult produces StringIndexOutOfBoundsException for groups outside match

[rgiulietti]

Fixes a bug showing up after JDK-8132995 when there are capturing groups outside the match.

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Issue

• JDK-8312976: MatchResult produces StringIndexOutOfBoundsException for groups outside match (Bug - P2)

Reviewers

• Alan Bateman (@AlanBateman - Reviewer)
• Stuart Marks (@stuart-marks - Reviewer)

Reviewing

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[rgiulietti]

Once integrated in mainline, the fix should be backported to 21, where the bug was introduced.

[mlbridge]

Webrevs

• 03: Full - Incremental (f117745d)
• 02: Full - Incremental (49fb4f14)
• 01: Full - Incremental (2b164c87)
• 00: Full (8c737329)

[AlanBateman]

This looks okay. I think its would be useful to get another reviewer to also look over this in case there is any other issues.

[openjdk]

@rgiulietti This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8312976: MatchResult produces StringIndexOutOfBoundsException for groups outside match

Reviewed-by: alanb, smarks

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At the time when this comment was updated there had been 42 new commits pushed to the master branch:

• 4577147: 8313712: [BACKOUT] 8313632: ciEnv::dump_replay_data use fclose
• bb3aac6: 8301606: JFileChooser file chooser details view "size" label cut off in Metal Look&Feel
• 0f2fce7: 8313632: ciEnv::dump_replay_data use fclose
• ab1c212: 8312909: C1 should not inline through interface calls with non-subtype receiver
• c386091: 8312984: javac may crash on a record pattern with too few components
• 3212b64: 8313582: Problemlist failing test on linux x86
• bdac348: 8313602: increase timeout for jdk/classfile/CorpusTest.java
• 58906bf: 4893524: Swing drop targets should call close() on transferred readers and streams
• 3c920f9: 8313274: [BACKOUT] Relax prerequisites for java.base-jmod target
• 53ca75b: 8313312: Add missing classpath exception copyright header
• ... and 32 more: https://git.openjdk.org/jdk/compare/5362ec9c6e9123d00288497ac9d1879a2bb1ca64...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[stuart-marks]

OK, changes and tests look good. Who knew, a capturing group could have bounds outside the matched string!

I did notice something that we might want to look at in the future. MatchResult has first and last fields; these seem redundant with the group[0] and group[1] entries. Indeed, Matcher also has first and last and the group[] array; start() returns first and end() returns last; while start(0) returns group[0] and end(0) returns group[1]. But the javadocs say that start() and start(0) are equivalent and that end() and end(0) are also equivalent. So Matcher also appears to have this redundancy. Since these values are all set by the matching engine in Pattern it seems like the redundancy is spread throughout the code.

Conceptually it might be possible for MatchResult to omit first and last and just use the first two group array entries, but it's really hard to verify this. Unclear whether this is worthwhile (and it's certainly not worth trying to include in this bugfix).

[rgiulietti]

Yes, I noticed that as well.

There's another PR aimed to reduce the length of the groups array when possible (currently, it is always sized for at least 10 pairs of (start, end) entries, even when only one pair is needed for group 0). That one is slated for >= 22, so I might be coordinated the future PR for the removal of the redundant first and last fields with that PR.

[rgiulietti]

/integrate

[openjdk]

Going to push as commit 61c58fd.
Since your change was applied there have been 47 commits pushed to the master branch:

• 5d23295: 8313251: Add NativeLibraryLoad event
• c4b8574: 8311938: Add default cups include location for configure on AIX
• 10a2605: 8294979: test/jdk/tools/jlink 3 test classes use ASM library
• e8c325d: 8313394: Array Elements in OldObjectSample event has the incorrect description
• d60352e: 8311006: missing @SInCE info in jdk.xml.dom
• 4577147: 8313712: [BACKOUT] 8313632: ciEnv::dump_replay_data use fclose
• bb3aac6: 8301606: JFileChooser file chooser details view "size" label cut off in Metal Look&Feel
• 0f2fce7: 8313632: ciEnv::dump_replay_data use fclose
• ab1c212: 8312909: C1 should not inline through interface calls with non-subtype receiver
• c386091: 8312984: javac may crash on a record pattern with too few components
• ... and 37 more: https://git.openjdk.org/jdk/compare/5362ec9c6e9123d00288497ac9d1879a2bb1ca64...master

Your commit was automatically rebased without conflicts.

[openjdk]

@rgiulietti Pushed as commit 61c58fd.

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