pkgs/mkEpicsPackage: switch to using epicsSetupHook

and add explainer comments

pkgs/build-support/mk-epics-package/default.nix

@@ -16,127 +16,43 @@
   depsBuildBuild ? [],
   nativeBuildInputs ? [],
   buildInputs ? [],
-  makeFlags ? [],
-  preBuild ? "",
-  postFixup ? "",
   ...
-} @ attrs:
-with lib; let
-  inherit (buildPackages) epnixLib;
-
+} @ attrs: let
   # remove non standard attributes that cannot be coerced to strings
   overridable = builtins.removeAttrs attrs ["local_config_site" "local_release"];
-  generateConf = (epnixLib.formats.make {}).generate;
-
-  # "build" as in Nix terminology (the build machine)
-  build_arch = epnixLib.toEpicsArch stdenv.buildPlatform;
-  # "host" as in Nix terminology (the machine which will run the generated code)
-  host_arch = epnixLib.toEpicsArch stdenv.hostPlatform;
+  generateConf = (buildPackages.epnixLib.formats.make {}).generate;
 in
   stdenv.mkDerivation (overridable
     // {
       strictDeps = true;
 
+      # When cross-compiling,
+      # epics will build every project twice,
+      # once "build -> build", and once "build -> host",
+      # so we need a compiler for the "build -> build" compilation.
       depsBuildBuild = depsBuildBuild ++ [buildPackages.stdenv.cc];
 
-      nativeBuildInputs = nativeBuildInputs ++ [makeWrapper perl readline];
-
-      # Also add perl into the non-native build inputs so that shebangs gets patched
-      buildInputs = buildInputs ++ [perl readline] ++ (optional (!isEpicsBase) [epnix.epics-base]);
-
-      makeFlags =
-        makeFlags
+      nativeBuildInputs =
+        nativeBuildInputs
         ++ [
-          "INSTALL_LOCATION=${placeholder "out"}"
+          makeWrapper
+          perl
+          readline
+          epnix.epicsSetupHook
         ];
 
-      PERL_HASH_SEED = 0;
+      # Also add perl into the non-native build inputs
+      # so that shebangs gets patched
+      buildInputs =
+        buildInputs
+        ++ [perl readline]
+        ++ (lib.optional (!isEpicsBase) epnix.epics-base);
 
       setupHook = ./setup-hook.sh;
 
-      # Defaults to true, EPICS' Makefile framework does usually support parallel builds
-      enableParallelBuilding = attrs.enableParallelBuilding or true;
-
-      dontConfigure = true;
-
-      local_config_site = generateConf ({
-          # This variable is used as a default version revision if no VCS is found.
-          #
-          # Since fetchgit and related fetchers remove the .git directory for
-          # reproducibility, EPICS fallsback to either the GENVERSIONDEFAULT variable
-          # if set (not the default), or the current date/time, which isn't
-          # reproducible.
-          GENVERSIONDEFAULT = "EPNix";
-          CROSS_COMPILER_TARGET_ARCHS =
-            if (stdenv.buildPlatform != stdenv.hostPlatform)
-            then host_arch
-            else null;
-
-          # This prevents EPICS from detecting installed libraries on the host
-          # system, for when Nix is compiling without sandbox (e.g.: WSL2)
-          GNU_DIR = "/var/empty";
-        }
-        // local_config_site);
-
-      # Undefine the SUPPORT variable here, since there is no single "support"
-      # directory and this variable is a source of conflicts between RELEASE files
-      local_release = generateConf (local_release // {SUPPORT = null;});
-
-      preBuild =
-        ''
-          echo "$local_config_site" > configure/CONFIG_SITE.local
-          echo "$local_release" > configure/RELEASE.local
-
-          # set to empty if unset
-          : "''${EPICS_COMPONENTS=}"
-
-          IFS=: read -ra components <<<$EPICS_COMPONENTS
-
-          for component in "''${components[@]}"; do
-            echo "$component"
-            echo "$component" >> configure/RELEASE.local
-          done
-
-          echo "=============================="
-          echo "CONFIG_SITE.local"
-          echo "------------------------------"
-          cat "configure/CONFIG_SITE.local"
-          echo "=============================="
-          echo "RELEASE.local"
-          echo "------------------------------"
-          cat "configure/RELEASE.local"
-          echo "------------------------------"
-
-        ''
-        + preBuild;
-
-      # Automatically create binaries directly in `bin/` that calls the ones that
-      # are in `bin/linux-x86_64/`
-      # TODO: we should probably do the same for libraries
-      #
-      # Don't do a manual `make install`, `make` already installs
-      # everything into `INSTALL_LOCATION`.
-      installPhase = ''
-        runHook preInstall
-
-        if [[ -d "$out/bin/${host_arch}" ]]; then
-          for file in "$out/bin/${host_arch}/"*; do
-            [[ -x "$file" ]] || continue
-
-            makeWrapper "$file" "$out/bin/$(basename "$file")"
-          done
-        fi
-
-        runHook postInstall
-      '';
+      local_config_site = generateConf local_config_site;
+      local_release = generateConf local_release;
 
       doCheck = attrs.doCheck or true;
       checkTarget = "runtests";
-
-      stripDebugList = attrs.stripDebugList or ["bin/${host_arch}" "lib/${host_arch}"];
-      postFixup =
-        optionalString (stdenv.buildPlatform != stdenv.hostPlatform) ''
-          stripDirs strip "bin/${build_arch} lib/${build_arch}" "-S"
-        ''
-        + postFixup;
     })

pkgs/build-support/mk-epics-package/setup-hook.sh

@@ -1 +1,5 @@
+# Export this package in a EPNix specific "EPICS_COMPONENTS" environment variable,
+# so that we are able to list every EPICS-specific packages,
+# to add them in the 'configure/RELEASE.local' file
+# in dependent packages.
 export "EPICS_COMPONENTS=${EPICS_COMPONENTS:+${EPICS_COMPONENTS}:}@varname@=@out@"