Henrik Nilsson wrote:
> [...] Well, ar does not support directories anyway, so if the objective
> here is to build a link library, the leaf names had better be distinct.
> (At least GNU make does seem to allow putting two object files with the
> same name into a link library if done as a single operation, but my guess
> is that doing so is asking for trouble.) [...]
Allowing leaf names to be equal is essential for the whole hierarchical
module business! Otherwise you would get evil non-local interactions
between different modules. And in practice it doesn't seem to be a problem
for ar/ld, because the base package and the GLUT package have lots of
examples for equal leaf names (see below). I'm not sure how ar/ld handle
this exactly, but I guess it works because of an index in the archive. From
the Linux ar man page:
...
ar creates an index to the symbols defined in relocatable
object modules in the archive when you specify the modi
fier s. Once created, this index is updated in the
archive whenever ar makes a change to its contents (save
for the q update operation). An archive with such an
index speeds up linking to the library, and allows rou
tines in the library to call each other without regard to
their placement in the archive.
You may use nm -s or nm --print-armap to list this index
table. If an archive lacks the table, another form of ar
called ranlib can be used to add just the table.
...
Newer ar versions to add this index automatically, other need an explicit
ranlib. The GHC installation process takes care of that automatically.
Cheers,
S.
---------------------------------------------------------------------------
Leaf name "clashes" in the current GHC version:
libHSGLUT.a:
Graphics.UI.GLUT.Window
Graphics.UI.GLUT.Callbacks.Window
libHSbase.a:
Data.Array
Foreign.Marshal.Array
Data.Array.Base
GHC.Base
Data.Char
Text.ParserCombinators.Parsec.Char
Control.Monad.Error
Foreign.C.Error
Foreign.Marshal.Error
System.IO.Error
Text.ParserCombinators.Parsec.Error
Control.Exception
GHC.Exception
Data.Array.IO
GHC.IO
System.IO
Data.Int
GHC.Int
Control.Monad.ST.Lazy
Data.STRef.Lazy
Control.Monad.List
Data.List
GHC.List
GHC.Posix
Text.Regex.Posix
Foreign.Ptr
GHC.Ptr
GHC.Read
Text.Read
Data.STRef
GHC.STRef
Control.Monad.ST
Data.Array.ST
GHC.ST
GHC.Show
Text.Show
Data.Array.Storable
Foreign.Storable
GHC.Storable
Control.Monad.ST.Strict
Data.STRef.Strict
Foreign.C.Types
System.Posix.Types
Debug.QuickCheck.Utils
Foreign.Marshal.Utils
GHC.Weak
System.Mem.Weak
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