Skip to:

  1. Skip to Jira Navigation
  2. Skip to Side Navigation
  3. Skip to Main Content

S6916: Quickfix suggesting to merge single if into existing pattern guard does not take operators precedence into account

Description

Suggested quickfixes sometimes change the semantics of the code. E.g. in this case:

Sonar-Java suggests to turn the first case into the following:

Now suppose for instance that x == -1. Then the original version of the code would not execute the print statement, whereas the version after applying the quickfix would.

Note that the same problem has already been solved in S1066.

Activity

Marco KaufmannSeptember 13, 2024 at 12:41 PM
Edited

I have some general doubt about this rule, because it always changes semantics. What we see here is two separate problems. 1. the missing parenthesis, which are fixed for S10166, and are fixed for S6916 in this PR. But there is still 2.: when we change

to

then in the original code in line 3, b is evaluated on !a || !x, but in the code after refactoring on !a || !x || !y. I.e. the condition under which the case is checked changes. So in the general case, collapsing an inner if with an outer when always changes semantics.

Here is an example in which this changes program behavior.

A different output is produced by collapsed and uncollapsed:

Done
Pinned fields
Click on the next to a field label to start pinning.

Details

Assignee

Reporter

Start date

Components

Fix versions

Due date

Priority

Parent

Sentry

Created April 29, 2024 at 9:53 AM
Updated October 16, 2024 at 2:11 PM
Resolved September 23, 2024 at 8:49 AM