Log compiler output atomically and only on debug mode

[agu-z]

Problem

The core compiler uses functions such as putStrLn, putStrFlush, hPutStr, and Text.PrettyPrint.ANSI.Leijen.displayIO to print to stdout and stderr as it compiles, downloads dependencies, displays errors, etc.

Also, the Watchtower.Find module uses print.

Running these functions without a lock can create garbled output, which can have very undesirable consequences, such as having your computer beep at you or open Print dialogs 🙃

Solution

Use Ext.Common.debug instead of putStrLn (et al), and introduce Ext.Common.withPrintLockIfDebug to wrap calls to Text.PrettyPrint.ANSI.Leijen so that its IO is performed atomically.

[supermario]

Nice 👍