[Haskell-cafe] Same code, system, but different arch using Win32 for reading registry.

Akos Marton makos999 at gmail.com
Mon Apr 10 18:17:44 UTC 2017

On 04/07/2017 05:09 PM, Brandon Allbery wrote:
> On Fri, Apr 7, 2017 at 3:51 PM, Akos Marton <makos999 at gmail.com> wrote:
>> *me.exe: RegOpenKey: invalid argument (The system cannot find the file
>> specified.)*
>> That would be fine, however the key does exists. When same code, same
>> system, but the .exe built to be x64 it runs like a charm.
> My guess is that the FFI call has an incorrect type somewhere and therefore
> passes garbage.
My fear is that, even if digging into the code of win32 package, 
underlying details seems to be hidden how certain values are read out. - 
at least for me.
Can it be that ghc forces its evaluation during compilation and renders 
something hard-coded into the binary? - this is how it feels, I am 
trying to show it, so far w/o success.

> Another thing which convoluted in the issue...
>> The function, *getSystemInfo :: IO SYSTEM_INFO, *can read out the
>> underlying architecture. When compiled on x86 and run on x64 it would tell
>> me: "I am running on x86". That's failure.
> You can blame Windows for that one: if you run an x86 binary on x86_64, it
> launches the WoW subsystem emulating an x86 processor, so you will get the
> emulated processor reported back. There may be a different API to get the
> actual host --- but given that WoW exists to minimize incompatibilities for
> x86 software, it is likely well hidden if it exists at all.
I do not know that, but it feels like I should use something which can 
be called via /system/ and hence on can rely on the local window api and 
not on the system I compile.
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