[java] InsufficientStringBufferDeclaration doesn't handle non-constant conditionals

[jsotuyod]

Affects PMD Version:
7.0.0

Rule:

InsufficientStringBufferDeclaration

Description:

When reducing the expression to compute the size, the rule fails to process non-constant conditions. But in doing so, misses that some branches may effectively allocate too small a buffer.

Ideally, these expressions would be reduced to retrieve the minimum possible value to analyze, as the rule checks against the minimum number of appended chars expected.

Code Sample demonstrating the issue:

public class ConditionalExpression {
    public void bar(int arg) {
        StringBuffer sb = new StringBuffer(arg > 1 ? 500 : 2);  // Should report a warning at this line, 2 is too small
        sb.append('a');
        sb.append('a');
        sb.append('a');
    }
}

Expected outcome:

PMD should report a violation at line 3, but doesn't. This is a false-negative.

Running PMD through: [CLI | Ant | Maven | Gradle | Designer | Other]
Any