#14234: Enable -Wconversion for GHC's C code -------------------------------------+------------------------------------- Reporter: nh2 | Owner: (none) Type: task | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Because apparently none of `-Wall`, `-Wextra` or `-pedantic` of GCC imply `-Wconversion` or its subset `-Wsign-conversion`: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=51625 That means currently you can call a function taking an `unsigned int` with a `signed int` without getting any warning. That is very bad, because of course negative numbers will overflow. Having `-Wconversion` would have caught overflow errors such as this one: https://phabricator.haskell.org/D3955#110993 We should probably have it for the C code. Turning it on everywhere will be quite some work though because it creates lots of complaints such as `long long int` not being the same as `long int` (which is technically correct but in practice they are typically the same). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14234 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler