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Workaround for ghcjs hardcoding to linux #511

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1 change: 1 addition & 0 deletions default.nix
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ let iosSupport = system == "x86_64-darwin";
inherit (self) lib;
haskellLib = self.haskell.lib;
inherit
system
useFastWeak useReflexOptimizer enableLibraryProfiling enableTraceReflexEvents
useTextJSString enableExposeAllUnfoldings
haskellOverlays;
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5 changes: 3 additions & 2 deletions haskell-overlays/default.nix
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
{ lib
{ system
, lib
, haskellLib
, nixpkgs
, useFastWeak, useReflexOptimizer, enableLibraryProfiling, enableTraceReflexEvents
Expand Down Expand Up @@ -112,7 +113,7 @@ rec {

# Just for GHCJS
ghcjs = import ./ghcjs.nix {
inherit lib haskellLib nixpkgs fetchgit fetchFromGitHub useReflexOptimizer;
inherit system lib haskellLib nixpkgs fetchgit fetchFromGitHub useReflexOptimizer;
};
ghcjs-fast-weak = import ./ghcjs-fast-weak {
inherit lib;
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18 changes: 16 additions & 2 deletions haskell-overlays/ghcjs.nix
Original file line number Diff line number Diff line change
@@ -1,8 +1,20 @@
{ lib, haskellLib, nixpkgs, fetchgit, fetchFromGitHub, useReflexOptimizer }:
{ system, lib, haskellLib, nixpkgs, fetchgit, fetchFromGitHub, useReflexOptimizer }:

with haskellLib;

self: super: {
self: super:

# Workaround for https://github.com/ghcjs/ghcjs/issues/674
# 'os (osx)' will always evaluate to 'false'
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let dontHardcodeLinux = package: cabalFile:
if ! self.ghc.isGhcjs then package
else nixpkgs.haskell.lib.overrideCabal package (drv: {
postPatch = (drv.postPatch or "") + nixpkgs.lib.optionalString (system == "x86_64-darwin") ''
substituteInPlace ${cabalFile}.cabal --replace 'if os(linux)' 'if os(linux) && !impl(ghcjs)'
substituteInPlace ${cabalFile}.cabal --replace 'if os(osx)' 'if os(linux) && impl(ghcjs)'
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Is this right? if os(osx) gets translated to if os(linux) ...?

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If it is right...an explanation is worthy.

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Talked to @alexfmpe. So basically this is just a very confusing way of writing it. Because of the hardcoding in GHCJS, os(linux) == true and true && x == x so why are we confounding this substitution?

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We don't want the os(linux) patches to get applied, so we change the os(linux) conditional to only apply when GHCJS isn't being used. Since GHCJS always thinks it's running on Linux, we change the os(osx) patches to os(linux) patches.

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because we don't want to apply the actual os(linux) patches (since we're really on macOS)

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GHCJS thinks we're on Linux, but that doesn't mean we should apply the Linux patches, instead we need to trick GHCJS into applying the macOS patches

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so we say "these linux patches are not for you, silly GHCJS, but these other (actually macOS) linux patches are!"

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Note the replacement only happens if system == "x86_64-darwin"

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That makes sense. Thanks.

'';
});
in {
_dep = super._dep or {} // {
ghcjsBaseSrc = fetchgit {
url = "https://github.com/ghcjs/ghcjs-base.git";
Expand Down Expand Up @@ -82,4 +94,6 @@ self: super: {
sha256 = "1sy51nz096sv91nxqk6yk7b92b5a40axv9183xakvki2nc09yhqg";
};
}));

foundation = dontHardcodeLinux super.foundation "foundation";
}