Implementing Code Coverage with -toolexec
summary
Explains how Go’s coverage works by recreating it with -toolexec, showing the actual instrumentation format (legacy text), the runtime limitation that forces a deferred dump in main instead of the internal coverage hook, and how the build graph and linker importcfg (about 47 packages in the example) drive ordering. Implements per-compile instrumentation, a cache keyed from object IDs, generates a helper package and rebuilds main with export and patched importcfg; admits the result is kludgy and “mostly works.”
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chapters (4)
- 0:00Understanding code coverage
- 2:03Analyzing the action graph
- 3:57Implementing custom coverage
- 5:59Challenges and solutions
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