Remove components.all (#776)

It causes a lot of issues. To make this work:

* `shellFor` is updated to use `getAllComponents` instead of `.all`.
* `getAllComponents` is updated to work on the package rather than
  the package config.
* Tests updated to not use `.library` or `.exes.X` where appropriate.
* Documentation updated.
* Out of date examples removed.

As a bonus `shellFor` now takes a `components` argument that might be
useful for limiting the dependencies of the shell to just the ones
needed for the components you intend to work on.

builder/comp-builder.nix

@@ -65,9 +65,7 @@ let
     then builtins.trace ("Cleaning component source not supported for hpack package: " + name) src
     else haskellLib.cleanCabalComponent package component src;
 
-  nameOnly = if haskellLib.isAll componentId
-    then "${package.identifier.name}-all"
-    else "${package.identifier.name}-${componentId.ctype}-${componentId.cname}";
+  nameOnly = "${package.identifier.name}-${componentId.ctype}-${componentId.cname}";
 
   fullName = "${nameOnly}-${package.identifier.version}";
 
@@ -293,7 +291,7 @@ let
       in ''
       runHook preInstall
       $SETUP_HS copy ${lib.concatStringsSep " " setupInstallFlags}
-      ${lib.optionalString (haskellLib.isLibrary componentId || haskellLib.isAll componentId) ''
+      ${lib.optionalString (haskellLib.isLibrary componentId) ''
         $SETUP_HS register --gen-pkg-config=${name}.conf
         ${ghc.targetPrefix}ghc-pkg -v0 init $out/package.conf.d
         if [ -d "${name}.conf" ]; then
@@ -326,7 +324,7 @@ let
           echo "package-id $id" >> $out/envDep
         fi
       ''}
-      ${(lib.optionalString (haskellLib.isTest componentId || haskellLib.isBenchmark componentId || haskellLib.isAll componentId) ''
+      ${(lib.optionalString (haskellLib.isTest componentId || haskellLib.isBenchmark componentId) ''
         mkdir -p $out/bin
         if [ -f ${testExecutable} ]; then
           mkdir -p $(dirname $out/bin/${exeName})

builder/shell-for.nix

@@ -1,11 +1,20 @@
 { lib, stdenv, glibcLocales, pkgconfig, ghcForComponent, makeConfigFiles, hsPkgs, hoogleLocal, haskellLib, buildPackages, compiler }:
 
-{ packages ? ps:
+{ # `packages` function selects packages that will be worked on in the shell itself.
+  # These packages will not be built by `shellFor`, but their
+  # dependencies will be included in the shell's `ghc-pkg list`.
+  packages ? ps:
     let
       selected = haskellLib.selectLocalPackages ps;
     in
       builtins.trace ("Shell for " + toString (builtins.attrNames selected))
         (builtins.attrValues selected)
+  # `components` function selects components that will be worked on in the shell itself.
+  # By default `shellFor` will include the dependencies of all of the components
+  # in the selected packages.  If only as subset of the components will be
+  # worked on in the shell then we can pass a different `components` function
+  # to select those.
+, components ? ps: lib.concatMap haskellLib.getAllComponents (packages hsPkgs) 
 , additional ? _: []
 , withHoogle ? true
 , exactDeps ? false
@@ -16,8 +25,9 @@ let
   # TODO find out why hoogle index creation can be made to work for cross compilers
   withHoogle' = withHoogle && !haskellLib.isCrossHost;
   selected = packages hsPkgs;
+  selectedComponents = components hsPkgs;
   additionalSelected = additional hsPkgs;
-  selectedConfigs = map (p: p.components.all.config) selected;
+  selectedConfigs = map (c: c.config) selectedComponents;
 
   name = if lib.length selected == 1
     then "ghc-shell-for-${(lib.head selected).identifier.name}"
@@ -45,9 +55,9 @@ let
   # Add the system libraries and build tools of the selected haskell
   # packages to the shell.
   systemInputs = removeSelectedInputs (lib.concatMap
-    (p: p.components.all.buildInputs ++ p.components.all.propagatedBuildInputs) selected);
+    (c: c.buildInputs ++ c.propagatedBuildInputs) selectedComponents);
   nativeBuildInputs = removeSelected
-    (lib.concatMap (p: p.components.all.executableToolDepends) selected);
+    (lib.concatMap (c: c.executableToolDepends) selectedComponents);
 
   # Set up a "dummy" component to use with ghcForComponent.
   component = {

changelog.md

@@ -1,6 +1,11 @@
 This file contains a summary of changes to Haskell.nix and `nix-tools`
 that will impact users.
 
+## July 21, 2020
+* Removed `components.all`, use `symlinkJoin` on components.exes or
+ `shellFor` if you need a shell.
+* Added `components` arguemnt to `shellFor`.
+
 ## July 21, 2020
 * Added GHC 8.8.4 and replaced 8.8.3 in tests and as the ghc
   used to build nix-tools for stack projects.

docs/reference/library.md

@@ -70,7 +70,6 @@ components = {
   exes = { NAME = COMPONENT; };
   tests = { NAME = COMPONENT; };
   benchmarks = { NAME = COMPONENT; };
-  all = COMPONENT;
 }
 ```
 
@@ -80,9 +79,6 @@ In [Haskell.nix][], a _component_ is a derivation corresponding to a
 [Cabal component](https://www.haskell.org/cabal/users-guide/developing-packages.html)
 of a package.
 
-[Haskell.nix][] also defines a special `all` component, which is the
-union of all components in the package.
-
 ## Identifier
 
 A package identifier is an attrset pair of `name` and `version`.
@@ -427,6 +423,7 @@ shellFor =
 | Argument       | Type | Description         |
 |----------------|------|---------------------|
 | `packages`     | Function | Package selection function. It takes a list of [Haskell packages](#haskell-package) and returns a subset of these packages. |
+| `components`   | Function | Similar to `packages`, by default all the components of the selected packages are selected. |
 | `additional`   | Function | Similar to `packages`, but the selected packages are built and included in `ghc-pkg list` (not just their dependencies). |
 | `withHoogle`   | Boolean  | Whether to build a Hoogle documentation index and provide the `hoogle` command. |
 | `exactDeps`    | Boolean  | Prevents the Cabal solver from choosing any package dependency other than what are in the package set. |

docs/tutorials/development.md

@@ -24,25 +24,9 @@ it exists in a file called `default.nix`.
     on it.  Starting Cabal 3.0 `cabal build` will work out of the box, as
     new style builds are the default.
 
-## How to get a development shell for a package
+## How to get a development shell
 
-Run a `nix‑shell` on `components.all` of your package. `all` is a
-synthetic component whose dependencies are the union of the
-dependencies of all components in the package. Therefore, you will be
-able to build the test suites because their dependencies will be
-included.
-
-```nix
-# shell.nix
-let
-  hsPkgs = import ./default.nix {};
-in
-  hsPkgs.my-package.components.all
-```
-
-## How to get a development shell for a multi-package project
-
-If you have a Cabal or Stack project with multiple packages
+If you have a Cabal or Stack project with one or more packages
 (i.e. multiple `.cabal` files, not a single package with multiple
 components), then you will need a development environment that
 contains the _dependencies_ of your packages, but not the packages