diff options
| -rw-r--r-- | .gitignore | 8 | ||||
| -rw-r--r-- | compiler/typecheck/TcRnExports.hs | 13 | ||||
| -rw-r--r-- | docs/users_guide/bugs.rst | 28 | ||||
| -rw-r--r-- | testsuite/tests/module/T13704.hs | 3 | ||||
| -rw-r--r-- | testsuite/tests/module/all.T | 2 |
5 files changed, 45 insertions, 9 deletions
diff --git a/.gitignore b/.gitignore index c72d044473..83fa7ececb 100644 --- a/.gitignore +++ b/.gitignore @@ -208,4 +208,10 @@ GIT_COMMIT_ID # ----------------------------------------------------------------------------- # Output of ghc-in-ghci -/.ghci-objects/
\ No newline at end of file +/.ghci-objects/ + +# ----------------------------------------------------------------------------- +# ghc.nix +ghc.nix/ + + diff --git a/compiler/typecheck/TcRnExports.hs b/compiler/typecheck/TcRnExports.hs index dbe2b4b22b..1b57608a41 100644 --- a/compiler/typecheck/TcRnExports.hs +++ b/compiler/typecheck/TcRnExports.hs @@ -33,7 +33,7 @@ import DataCon import PatSyn import Maybes import Util (capitalise) - +import FastString (fsLit) import Control.Monad import DynFlags @@ -124,19 +124,18 @@ tcRnExports explicit_mod exports -- list, to avoid bleating about re-exporting a deprecated -- thing (especially via 'module Foo' export item) do { - -- If the module header is omitted altogether, then behave - -- as if the user had written "module Main(main) where..." - -- EXCEPT in interactive mode, when we behave as if he had + -- In interactive mode, we behave as if he had -- written "module Main where ..." - -- Reason: don't want to complain about 'main' not in scope - -- in interactive mode ; dflags <- getDynFlags + ; let default_main = case mainFunIs dflags of + Just main_fun -> mkUnqual varName (fsLit main_fun) + Nothing -> main_RDR_Unqual ; let real_exports | explicit_mod = exports | ghcLink dflags == LinkInMemory = Nothing | otherwise = Just (noLoc [noLoc (IEVar noExt - (noLoc (IEName $ noLoc main_RDR_Unqual)))]) + (noLoc (IEName $ noLoc default_main)))]) -- ToDo: the 'noLoc' here is unhelpful if 'main' -- turns out to be out of scope diff --git a/docs/users_guide/bugs.rst b/docs/users_guide/bugs.rst index aee8dc5842..0290622b62 100644 --- a/docs/users_guide/bugs.rst +++ b/docs/users_guide/bugs.rst @@ -173,6 +173,34 @@ same context. For example, this is fine: :: .. _infelicities-Modules: +Default Module headers with -main-is +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The Haskell2010 report specifies in <https://www.haskell.org/onlinereport/haskell2010/haskellch5.html#x11-990005.1> that + + "An abbreviated form of module, consisting only of the module body, + is permitted. If this is used, the header is assumed to be + `module Main(main) where`." + +Consider the following program: :: + + -- file: Main.hs + program :: IO () + program = return () + +Under the report, this would fail with ``ghc -main-is Main.program Main.hs`` +with the following errors: :: + + Main.hs:1:1: error: + Not in scope: 'main' + Perhaps you meant 'min' (imported from Prelude) + + Main.hs:1:1: error: + The main IO action 'program' is not exported by module 'Main' + +GHC's flag '-main-is' allows one to change the entry point name so that +the above example would succeed. + Module system and interface files ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/testsuite/tests/module/T13704.hs b/testsuite/tests/module/T13704.hs new file mode 100644 index 0000000000..38b1cb73fc --- /dev/null +++ b/testsuite/tests/module/T13704.hs @@ -0,0 +1,3 @@ +program = return () + +-- meant to be compiled with 'ghc -main-is Main.program T13704.hs' diff --git a/testsuite/tests/module/all.T b/testsuite/tests/module/all.T index e862413897..dbba44f0ba 100644 --- a/testsuite/tests/module/all.T +++ b/testsuite/tests/module/all.T @@ -284,4 +284,4 @@ test('T11970B', normal, compile_fail, ['']) test('MultiExport', normal, compile, ['']) test('T13528', normal, compile, ['']) test('T13622', normal, compile, ['']) - +test('T13704', normal, compile, ['-main-is Main.program']) |