#10895: "no output will be generated" should be an error, not a warning. -------------------------------------+------------------------------------- Reporter: gershomb | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: -------------------------------------+------------------------------------- Description changed by gershomb: Old description:

Consider a file "Test.hs" which has a "main" function but is declared as "module Test where..."

If we attempt to compile it, we get the following warning:

{{{ Warning: output was redirected with -o, but no output will be generated because there is no Main module. }}}

This should be upgraded from a warning to an error. This would help e.g. Cabal, because such warnings do not lead to a failure of the wrapping Cabal process, which is confusing to end-users.

For gory details, see e.g. discussion at https://github.com/haskell/cabal/issues/1847

New description: Consider a file "Test.hs" which has a "main" function but is declared as "module Test where..." If we attempt to compile it with for example "ghc --make Test.hs -o Test", we get the following warning: {{{ Warning: output was redirected with -o, but no output will be generated because there is no Main module. }}} This should be upgraded from a warning to an error. This would help e.g. Cabal, because such warnings do not lead to a failure of the wrapping Cabal process, which is confusing to end-users. For gory details, see e.g. discussion at https://github.com/haskell/cabal/issues/1847 -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10895#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10895: "no output will be generated" should be an error, not a warning. -------------------------------------+------------------------------------- Reporter: gershomb | Owner: Type: bug | Status: patch Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1253 -------------------------------------+------------------------------------- Changes (by thomie): * status: new => patch * differential: => Phab:D1253 * milestone: => 8.0.1 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10895#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#10895: "no output will be generated" should be an error, not a warning. -------------------------------------+------------------------------------- Reporter: gershomb | Owner: Type: bug | Status: closed Priority: normal | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Incorrect | Test Case: warning at compile-time | driver/should_fail/T10895 Blocked By: | Blocking: Related Tickets: | Differential Revisions: Phab:D1253 -------------------------------------+------------------------------------- Changes (by thomie): * status: patch => closed * testcase: => driver/should_fail/T10895 * resolution: => fixed Comment: Thanks for the suggestion. Should be fixed in ghc-8. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10895#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler