Dynamic types: GHCI works, GHC doesn't?
Sat, 1 Jun 2002 23:23:49 +1000
On Sat, Jun 01, 2002 at 11:01:57PM +1000, Andre Pang wrote:
> It seems that the fromDynamic and fromDyn functions seem to work
> if you load your module into GHCI, but they don't work when you
> compile it into a stand-alone executable with GHC.
.. unless you compile it with -O2:
23:18(0) .../project/dynamic_types-bug% ghc --make -package lang -O2 DynamicTypesBug.hs
ghc-5.02.2: chasing modules from: DynamicTypesBug.hs
Compiling Main ( DynamicTypesBug.hs, ./DynamicTypesBug.o )
ghc: linking ...
23:18(0) .../project/dynamic_types-bug% ./a.out
Static type: FootnoteData [Char] Int
Coerced (dynamic) type: FootnoteData [Char] Int
Does dynamic type == static type? True
Attempting to run fromDynamic on the dynamic type ...
5. This be the footnote
It also seems to work with -O1.
I should note that I observed the buggy GHC behaviour with
-fvia-c as well, regardless of whether gcc-2.95 or gcc-3.1 was
Putting -O0 on the GHC commandline, or omitting the -O option
altogether, appears to trigger the bug. This doesn't happen with
GHCI (i.e. 'ghci -O0' seems to work).
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