Hi Norman, in addition to what Ben already said: is there any particular reason you wanted to use the stage0 compiler? I have written a small program against HEAD which used the GHC API fairly recently, and I have simply used the `stage1` compiler. An excerpt from my little code snippet: ``` -- This is just the output of '_build/stage1/bin/ghc --print-libdir' myGhcLibDir :: FilePath myGhcLibDir = "./_build/stage1/lib" playground :: FilePath -> IO () playground fn = do res <- runGhc (Just myGhcLibDir) $ do ... ``` As you can see that's exactly what you are doing, modulo the fact I was using the `stage1` (where _build is the default directory for Hadrian builds). Hope this helps in some way! A. On Fri, 24 Sept 2021 at 03:37, Ben Gamari wrote:

Norman Ramsey writes:

...

I'm writing client code against the GHC API in HEAD (version 9.3), using 9.0.1 as my bootstrap compiler. To make it possible to build this code, I've set up cabal using

cabal v1-configure \ --package-db clear \ --package-db $STAGE0/lib/package.conf.d/ # stage0 libraries

In my Haskell code I'm invoking `runGhc (Just thelibdir)` where

thelibir = "/home/nr/asterius/ghc/_build/stage0/lib"

which is my `$STAGE0/lib`.

Unfortunuately, when I launch my app, `setSessionDynFlags` panics. The output, along with some diagnostic information about some dflags that seemed relevant, looks like this:

libdir = /home/nr/asterius/ghc/_build/stage0/lib includePaths = IncludeSpecs {includePathsQuote = [], includePathsGlobal = [], includePathsQuoteImplicit = []} libraryPaths = [] packageDBFlags = [] packageEnv = Nothing panic! (the 'impossible' happened) GHC version 9.3.20210918: GHC couldn't find the RTS constants (#define HS_CONSTANTS ") in /home/nr/.ghcup/ghc/9.0.1/lib/ghc-9.0.1/include/DerivedConstants.h: the RTS package you are trying to use is perhaps for another GHC version(e.g. you are using the wrong package database) or the package database is broken.

CallStack (from HasCallStack): error, called at _build/stage0/compiler/build/GHC/Platform/Constants.hs:143:20 in ghc:GHC.Platform.Constants

Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug

I'm a little suprprised that my app is hunting for 9.3 information in the tree that belongs to the bootstrap compiler.

I suspect that the stages are getting mixed up here. Would it be possible to post a full reproducer? I'd be happy to investigate further, but without being able to reproduce locally it's a bit hard to say anything useful. My recollection is that we look for DerivedConstants.h in the usual include paths, so there are many ways in which things could go wrong.

Cheers,

- Ben _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs

Alfredo, I've confirmed that I can use the stage1 compiler and it doesn't panic. It occurs to me that I might be able to *compile* my code with the stage1 compiler while using the bootstrap compiler and Haskell Language Server. I'll give that a shot. Norman

Hi Norman,

in addition to what Ben already said: is there any particular reason you wanted to use the stage0 compiler? I have written a small program against HEAD which used the GHC API fairly recently, and I have simply used the `stage1` compiler. An excerpt from my little code snippet:

``` -- This is just the output of '_build/stage1/bin/ghc --print-libdir' myGhcLibDir :: FilePath myGhcLibDir = "./_build/stage1/lib"

playground :: FilePath -> IO () playground fn = do res <- runGhc (Just myGhcLibDir) $ do ... ```

As you can see that's exactly what you are doing, modulo the fact I was using the `stage1` (where _build is the default directory for Hadrian builds).

Hope this helps in some way!

A.

On Fri, 24 Sept 2021 at 03:37, Ben Gamari wrote:

...

Norman Ramsey writes:

...

I'm writing client code against the GHC API in HEAD (version 9.3), using 9.0.1 as my bootstrap compiler. To make it possible to build this code, I've set up cabal using

cabal v1-configure \ --package-db clear \ --package-db $STAGE0/lib/package.conf.d/ # stage0 libraries

In my Haskell code I'm invoking `runGhc (Just thelibdir)` where

thelibir = "/home/nr/asterius/ghc/_build/stage0/lib"

which is my `$STAGE0/lib`.

Unfortunuately, when I launch my app, `setSessionDynFlags` panics. The output, along with some diagnostic information about some dflags that seemed relevant, looks like this:

libdir = /home/nr/asterius/ghc/_build/stage0/lib includePaths = IncludeSpecs {includePathsQuote = [], includePathsGlobal = [], includePathsQuoteImplicit = []} libraryPaths = [] packageDBFlags = [] packageEnv = Nothing panic! (the 'impossible' happened) GHC version 9.3.20210918: GHC couldn't find the RTS constants (#define HS_CONSTANTS ") in /home/nr/.ghcup/ghc/9.0.1/lib/ghc-9.0.1/include/DerivedConstants.h: the RTS package you are trying to use is perhaps for another GHC version(e.g. you are using the wrong package database) or the package database is broken.

CallStack (from HasCallStack): error, called at _build/stage0/compiler/build/GHC/Platform/Constants.hs:143:20 in ghc:GHC.Platform.Constants

Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug

I'm a little suprprised that my app is hunting for 9.3 information in the tree that belongs to the bootstrap compiler.

I suspect that the stages are getting mixed up here. Would it be possible to post a full reproducer? I'd be happy to investigate further, but without being able to reproduce locally it's a bit hard to say anything useful. My recollection is that we look for DerivedConstants.h in the usual include paths, so there are many ways in which things could go wrong.

Cheers,

- Ben _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs