Commit 12a74444 authored by Moritz Angermann's avatar Moritz Angermann

Adds -ghc-version flag to ghc.

When building the rts with ghc (e.g. using ghc as a c compiler), ghc's
"Value Add"[1] is, it includes adding `-include /path/to/ghcversion.h`.  For
this it looksup the rts package in the package database, which--if
empty--fails.  Thus to allow compiling C files with GHC, we add the
`-ghc-version` flag, which takes the path to the `ghcversion.h` file.

A `-no-ghc-version` flag was omitted, as at that point it becomes
questionable why one would use ghc to compile c if one doesn't
any of the added value.


[1] from `compiler/main/DriverPipeline.hs`
>        -- add package include paths even if we're just compiling .c
>        -- files; this is the Value Add(TM) that using ghc instead of
>        -- gcc gives you :)

Reviewers: bgamari, geekosaur, austin

Reviewed By: bgamari

Subscribers: rwbarton, thomie

Differential Revision:
parent c7297342
......@@ -2204,11 +2204,16 @@ touchObjectFile dflags path = do
-- | Find out path to @ghcversion.h@ file
getGhcVersionPathName :: DynFlags -> IO FilePath
getGhcVersionPathName dflags = do
dirs <- getPackageIncludePath dflags [toInstalledUnitId rtsUnitId]
candidates <- case ghcVersion dflags of
Just path -> return [path]
Nothing -> (map (</> "ghcversion.h")) <$>
(getPackageIncludePath dflags [toInstalledUnitId rtsUnitId])
found <- filterM doesFileExist (map (</> "ghcversion.h") dirs)
found <- filterM doesFileExist candidates
case found of
[] -> throwGhcExceptionIO (InstallationError ("ghcversion.h missing"))
[] -> throwGhcExceptionIO (InstallationError
("ghcversion.h missing; tried: "
++ intercalate ", " candidates))
(x:_) -> return x
-- Note [-fPIC for assembler]
......@@ -534,6 +534,7 @@ data GeneralFlag
| Opt_ExternalInterpreter
| Opt_OptimalApplicativeDo
| Opt_VersionMacros
| Opt_GhcVersion
| Opt_WholeArchiveHsLibs
-- PreInlining is on by default. The option is there just to see how
......@@ -917,6 +918,7 @@ data DynFlags = DynFlags {
flushOut :: FlushOut,
flushErr :: FlushErr,
ghcVersion :: Maybe FilePath,
haddockOptions :: Maybe String,
-- | GHCi scripts specified by -ghci-script, in reverse order
......@@ -1682,6 +1684,7 @@ defaultDynFlags mySettings myLlvmTargets =
filesToClean = panic "defaultDynFlags: No filesToClean",
dirsToClean = panic "defaultDynFlags: No dirsToClean",
generatedDumps = panic "defaultDynFlags: No generatedDumps",
ghcVersion = Nothing,
haddockOptions = Nothing,
dumpFlags = EnumSet.empty,
generalFlags = EnumSet.fromList (defaultFlags mySettings),
......@@ -2339,6 +2342,9 @@ addDepSuffix s d = d { depSuffixes = s : depSuffixes d }
addCmdlineFramework f d = d { cmdlineFrameworks = f : cmdlineFrameworks d}
addGhcVersion :: FilePath -> DynFlags -> DynFlags
addGhcVersion f d = d { ghcVersion = Just f }
addHaddockOpts f d = d { haddockOptions = Just f}
addGhciScript f d = d { ghciScripts = f : ghciScripts d}
......@@ -2866,6 +2872,7 @@ dynamic_flags_deps = [
, make_ord_flag defGhcFlag "no-rtsopts-suggestions"
(noArg (\d -> d {rtsOptsSuggestions = False}))
, make_ord_flag defGhcFlag "ghc-version" (hasArg addGhcVersion)
, make_ord_flag defGhcFlag "main-is" (SepArg setMainIs)
, make_ord_flag defGhcFlag "haddock" (NoArg (setGeneralFlag Opt_Haddock))
, make_ord_flag defGhcFlag "haddock-opts" (hasArg addHaddockOpts)
......@@ -1064,3 +1064,26 @@ Some flags only make sense for particular target platforms.
and later). The :ref:`LLVM backend <llvm-code-gen>` will also use
SSE4.2 if your processor supports it but detects this automatically
so no flag is required.
Miscellaneous flags
.. index::
single: miscellaneous flags
Some flags only make sense for a particular use case.
.. ghc-flag:: -ghc-version ⟨path to ghcversion.h⟩
:shortdesc: (GHC as a C compiler only) Use this ``ghcversion.h`` file
:type: dynamic
:category: misc
When GHC is used to compile C files, GHC adds package include paths and
includes ``ghcversion.h`` directly. The compiler will lookup the path for
the ``ghcversion.h`` file from the ``rts`` package in the package database.
In some cases, the compiler's package database does not contain the ``rts``
package, or one wants to specify a specific ``ghcversions.h`` to be
included. This option can be used to specify the path to the
``ghcversions.h`` file to be included. This is primarily intended to be
used by GHC's build system.
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