Match wide local variable instruction length to dumped bytes

[rootvector2]

LocalVariableInstruction.initFromFile hardcodes length 4 for any wide-prefixed load or store, but dump() writes the wide prefix only when the index is above Const.MAX_BYTE. A wide iload 5 is legal bytecode whose index fits in a byte, so it parses with getLength() 4 while dump() emits 2 bytes. I hit this auditing wide handling against RET and IINC, which persist the parsed flag and keep the two in sync.

InstructionList.setPositions accumulates getLength(), so rebuilding a parsed method that carries one of these instructions shifts every following instruction 2 bytes and corrupts the branch offsets that span it. Deriving the parsed length from the same wide() test dump() already uses keeps length and emitted bytes in agreement, leaving the compact and non-wide paths untouched.

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[Copilot]

Pull request overview

This PR fixes a bytecode round-tripping inconsistency for wide-prefixed local-variable load/store instructions by ensuring the parsed instruction length matches what dump() will actually emit. This prevents InstructionList.setPositions() from accumulating an incorrect length and shifting subsequent instruction offsets when rebuilding methods.

Changes:

• Update LocalVariableInstruction.initFromFile() to set length based on the same wide() condition used by dump(), instead of always forcing length 4 for wide-prefixed parses.
• Add JUnit tests covering wide iload/istore cases where the parsed encoding is 4 bytes but the dumped encoding can be 2 bytes when the index fits in a byte.
• Ensure large-index wide instructions remain 4 bytes and round-trip consistently.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/main/java/org/apache/bcel/generic/LocalVariableInstruction.java	Aligns parsed length with emitted bytes by deriving length from wide() after reading the index.
src/test/java/org/apache/bcel/generic/LocalVariableInstructionTest.java	Adds regression tests asserting getLength() matches dump() output for wide/non-wide edge cases.

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