#13342: Core Lint warnings are emitted on stdout rather than stderr -------------------------------------+------------------------------------- Reporter: mpickering | Owner: (none) Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ThreeFx): Just a note: The culprit seems to be `displayLintResults` in `compiler/coreSyn/CoreLint.hs`. Using `log_action` with the severity `SevDump` writes the given text to `stdout`. By changing this to `SevWarning` it is written to `stderr` instead, although the error message is worse than before because it is even more redundant: {{{ <no location info>: warning: *** Core Lint warnings : in result of Occurrence analysis *** test.hs:4:1: warning: [RHS of f :: [()] -> [()]] INLINE binder is (non-rule) loop breaker: f }}} Since linting `Core` is a compiler developer thing 99% of the time, IMO it is more important to print concise and clear error messages/warnings than to write to the correct output (the first line overshadows the linting error). But these are just my 2 cents. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13342#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler