More windows woe

[Edward Z. Yang]

Yep, it's string concatenation, and it's ANSI C as per 5.1.1.2.  We use this
idiom in other parts of the RTS.

Cheers,
Edward

Excerpts from Simon Peyton-Jones's message of Wed Sep 04 02:22:48 -0700 2013:
>      IF_DEBUG(linker, debugBelch("Checking whether to unload " FMT_PATH "\n",
> 
> doesn't that expand to 
> 
>      IF_DEBUG(linker, debugBelch("Checking whether to unload " "%S" "\n",
> 
> What does the C compiler make of three strings in a row?  Does it automatically concatenate them? Is that ANSI C?
> 
> S
> 
> | -----Original Message-----
> | From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of Edward
> | Z. Yang
> | Sent: 04 September 2013 10:15
> | To: Jost Berthold
> | Cc: ghc-devs
> | Subject: Re: RE: More windows woe
> | 
> | I think this is reasonable, with the added caveat that
> | the macros should be placed in includes/rts/Linker.h, because that is
> | where pathchar is defined.  So how about something like:
> | 
> | diff --git a/includes/rts/Linker.h b/includes/rts/Linker.h
> | index e900e85..871b8cd 100644
> | --- a/includes/rts/Linker.h
> | +++ b/includes/rts/Linker.h
> | @@ -16,8 +16,10 @@
> | 
> |  #if defined(mingw32_HOST_OS)
> |  typedef wchar_t pathchar;
> | +#define FMT_PATH "%S"
> |  #else
> |  typedef char    pathchar;
> | +#define FMT_PATH "%s"
> |  #endif
> | 
> |  /* initialize the object linker */
> | diff --git a/rts/CheckUnload.c b/rts/CheckUnload.c
> | index a758b06..8dc8fdc 100644
> | --- a/rts/CheckUnload.c
> | +++ b/rts/CheckUnload.c
> | @@ -254,7 +254,7 @@ void checkUnload (StgClosure *static_objects)
> | 
> |    // Mark every unloadable object as unreferenced initially
> |    for (oc = unloaded_objects; oc; oc = oc->next) {
> | -      IF_DEBUG(linker, debugBelch("Checking whether to unload %s\n",
> | +      IF_DEBUG(linker, debugBelch("Checking whether to unload "
> | FMT_PATH "\n",
> |                                    oc->fileName));
> |        oc->referenced = rtsFalse;
> |    }
> | @@ -290,11 +290,11 @@ void checkUnload (StgClosure *static_objects)
> |            } else {
> |                prev->next = oc->next;
> |            }
> | -          IF_DEBUG(linker, debugBelch("Unloading object file %s\n",
> | +          IF_DEBUG(linker, debugBelch("Unloading object file " FMT_PATH
> | "\n",
> |                                        oc->fileName));
> |            freeObjectCode(oc);
> |        } else {
> | -          IF_DEBUG(linker, debugBelch("Object file still in use: %s\n",
> | +          IF_DEBUG(linker, debugBelch("Object file still in use: "
> | FMT_PATH "\n",
> |                                        oc->fileName));
> |        }
> |    }
> | diff --git a/rts/Linker.c b/rts/Linker.c
> | index 6490242..4f0a1c4 100644
> | --- a/rts/Linker.c
> | +++ b/rts/Linker.c
> | @@ -2790,7 +2790,7 @@ unloadObj( pathchar *path )
> | 
> |      initLinker();
> | 
> | -    IF_DEBUG(linker, debugBelch("unloadObj: %s\n", path));
> | +    IF_DEBUG(linker, debugBelch("unloadObj: " FMT_PATH "\n", path));
> | 
> |      prev = NULL;
> |      for (oc = objects; oc; prev = oc, oc = next) {
> | 
> | Excerpts from Jost Berthold's message of Tue Sep 03 12:56:03 -0700 2013:
> | > > From: Simon Peyton-Jones <simonpj at microsoft.com>
> | > > To: "Edward Z. Yang" <ezyang at MIT.EDU>, Simon Marlow
> | > >     <marlowsd at gmail.com>
> | > > Cc: "ghc-devs at haskell.org" <ghc-devs at haskell.org>
> | > > Subject: RE: More windows woe
> | > > Message-ID:
> | > >
> | <59543203684B2244980D7E4057D5FBC1485BB7AB at DB3EX14MBXC308.europe.corp.mic
> | rosoft.com>
> | > >
> | > > Content-Type: text/plain; charset="utf-8"
> | > >
> | > > Simon Marlow: please help!
> | > > At the moment windows builds are hosed, which is a Bad Situation.
> | > >
> | > > Actually it turns out that what want is
> | > >
> | > >    debugBelch("Checking whether to unload %S\n", oc->fileName));
> | > >
> | > > That is, use "%S" rather than "%s" as format specifier for wide
> | chars.
> | > >
> | > > Sadly, this works on Windows, but not on Linux:
> | > > rts/CheckUnload.c:260:13:
> | > >       error: format ?%S? expects argument of type ?wchar_t *?, but
> | argument 2 has type ?pathchar *? [-Werror=format]
> | > >
> | > >
> | > > So what I need guidance on, please!, is what the approved way to
> | deal with this is.  I suppose that I could identify each use of %s on a
> | filepath and say
> | > >
> | > > #ifdef mingw32_HOST_OS
> | > >    debugBelch("Checking whether to unload %S\n", oc->fileName));
> | > > #else
> | > >    debugBelch("Checking whether to unload %s\n", oc->fileName));
> | > > #endif
> | > >
> | > > But that seems deeply unsatisfactory doesn't it?
> | > >
> | > > If not that, then what?
> | > >
> | > >
> | > > Simon
> | >
> | > Similar code is in place to distinguish between 32-bit and 64-bit
> | StgWords:
> | >
> | >  > grep -r -e FMT_Word includes/
> | > includes/stg/Types.h:#define FMT_Word32    "u"
> | > includes/stg/Types.h:#define FMT_Word32    "lu"
> | > includes/stg/Types.h:#define FMT_Word64    "lu"
> | > includes/stg/Types.h:#define FMT_Word64    "llu"
> | > includes/stg/Types.h:#define FMT_Word     FMT_Word64
> | > includes/stg/Types.h:#define FMT_Word     FMT_Word32
> | >
> | > and format strings like "blabla " FMT_Word " ..blabla" are used inside
> | > rts/. One could do the same for FMT_Path and introduce it where
> | required.
> | >
> | > Maybe this would be acceptable?
> | >
> | > / Jost
> | >
> | 
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