Issue #22269 has been reported by mugikurash (Shuta Mugikura). ---------------------------------------- Bug #22269: `Coverage.line_stub` clobbers already-collected coverage data https://bugs.ruby-lang.org/issues/22269 * Author: mugikurash (Shuta Mugikura) * Status: Open * ruby -v: ruby 4.1.0dev (2026-08-27T01:47:31Z master 5ee95de080) +PRISM [arm64-darwin25] * Backport: 3.3: UNKNOWN, 3.4: UNKNOWN, 4.0: UNKNOWN ---------------------------------------- `Coverage.line_stub` compiles the file with `compile_file` only to read the ISeq's `trace_points`. Since https://bugs.ruby-lang.org/issues/22018 `compile_file` registers the file into the coverage table, so calling `line_stub` while `Coverage` is running resets the file's already-collected counters. This also reproduces on 3.4 and 4.0, so I would like it backported. Reproduction: ```ruby require "coverage" f = File.expand_path("m.rb") File.write(f, "def m\n :ok\nend\n") Coverage.start require f m p Coverage.peek_result[f] Coverage.line_stub(f) p Coverage.peek_result[f] m p Coverage.result[f] ``` Expected: ``` [1, 1, nil] [1, 1, nil] [1, 2, nil] ``` Actual: ``` [1, 1, nil] [0, 0, nil] [0, 0, nil] ``` -- https://bugs.ruby-lang.org/