[project @ 2004-02-24 15:18:27 by simonpj]

---------------------------------------
  	 Make foreign import "&foo" work in constructors
	  ---------------------------------------

		Merge to stable branch

A foreign-imported-label might be in another DLL or library, and
can't be in the read-only static data.  This showed up when compiling
unix/System/Posix/Env.hs without -O

diff --git a/ghc/compiler/coreSyn/CoreUtils.lhs b/ghc/compiler/coreSyn/CoreUtils.lhs
index 8e53bbc..39d2fcf 100644 (file)
--- a/ghc/compiler/coreSyn/CoreUtils.lhs
+++ b/ghc/compiler/coreSyn/CoreUtils.lhs
@@ -45,7 +45,7 @@ import Var            ( Var, isId, isTyVar )
 import VarEnv
 import Name            ( hashName, isDllName )
 import Literal         ( hashLiteral, literalType, litIsDupable, 
-                         litIsTrivial, isZeroLit )
+                         litIsTrivial, isZeroLit, Literal( MachLabel ) )
 import DataCon         ( DataCon, dataConRepArity, dataConArgTys,
                          isExistentialDataCon, dataConTyCon )
 import PrimOp          ( PrimOp(..), primOpOkForSpeculation, primOpIsCheap )
@@ -1239,7 +1239,19 @@ is_static False (Lam b e) = isRuntimeVar b || is_static False e
 
 is_static in_arg (Note (SCC _) e) = False
 is_static in_arg (Note _ e)       = is_static in_arg e
-is_static in_arg (Lit lit)        = True
+
+is_static in_arg (Lit lit)
+  = case lit of
+       MachLabel _ _ -> False
+       other         -> True
+       -- A MachLabel (foreign import "&foo") in an argument
+       -- prevents a constructor application from being static.  The
+       -- reason is that it might give rise to unresolvable symbols
+       -- in the object file: under Linux, references to "weak"
+       -- symbols from the data segment give rise to "unresolvable
+       -- relocation" errors at link time This might be due to a bug
+       -- in the linker, but we'll work around it here anyway. 
+       -- SDM 24/2/2004
 
 is_static in_arg other_expr = go other_expr 0
   where