There are potential problems with Array2DHashSet and FlexibleHashMap.

[yososs]

Incorrect threshold when initial container size is specified in the constructor.
The clear method ignores the container size specified in the constructor. Also, the threshold is not recalculated.

• https://github.com/antlr/antlr4/blob/master/runtime/Java/src/org/antlr/v4/runtime/misc/Array2DHashSet.java
• https://github.com/antlr/antlr4/blob/master/runtime/Java/src/org/antlr/v4/runtime/misc/FlexibleHashMap.java

Currently, these are not causing any real problems because of the following assumptions.

• Using an initial container size of 16.
• They are not (presumably) using the clear method.

In class member declarations, the values of threshold are as follows

public static final int INITAL_CAPACITY = 16; // must be power of 2

protected int threshold = (int)Math.floor(INITAL_CAPACITY * LOAD_FACTOR); // when to expand

Thus, even if a large value is specified for initialCapacity in the Array2DHashSet constructor, the first expansion is done at the threshold value of 16*0.75.

The implementation of clear also ignores the constructor parameter and is considered incorrect.

The code to correct this problem is attached.

• patch.zip

[parrt]

yep, makes sense. code is wrong in antlr; but didn't affect anything. whew. Making a PR. #3726

[KvanTTT]

Probably it should be converted to an issue and closed.