Stratify `ExtraPathInfo` along `Installable` hierarchy

Instead of having a bunch of optional fields, have a few subclasses
which can have mandatory fields.

Additionally, the new `getExtraPathInfo`, and `nixpkgsFlakeRef`, are
moved to `InstallableValue`.

I did these things because https://github.com/NixOS/rfcs/pull/134 ; with
these things moved to `InstallableValue`, the base `Installable` no
longer depends on libexpr! This is a major step towards that.

Also, add a bunch of doc comments for sake of the internal API docs.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index f06ade008..d8de20586 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -1,6 +1,6 @@
 #include "eval.hh"
-#include "command.hh"
 #include "installable-flake.hh"
+#include "command-installable-value.hh"
 #include "common-args.hh"
 #include "shared.hh"
 #include "store-api.hh"
@@ -252,7 +252,7 @@ static StorePath getDerivationEnvironment(ref<Store> store, ref<Store> evalStore
     throw Error("get-env.sh failed to produce an environment");
 }
 
-struct Common : InstallableCommand, MixProfile
+struct Common : InstallableValueCommand, MixProfile
 {
     std::set<std::string> ignoreVars{
         "BASHOPTS",
@@ -374,7 +374,7 @@ struct Common : InstallableCommand, MixProfile
         return res;
     }
 
-    StorePath getShellOutPath(ref<Store> store, ref<Installable> installable)
+    StorePath getShellOutPath(ref<Store> store, ref<InstallableValue> installable)
     {
         auto path = installable->getStorePath();
         if (path && hasSuffix(path->to_string(), "-env"))
@@ -393,7 +393,7 @@ struct Common : InstallableCommand, MixProfile
     }
 
     std::pair<BuildEnvironment, std::string>
-    getBuildEnvironment(ref<Store> store, ref<Installable> installable)
+    getBuildEnvironment(ref<Store> store, ref<InstallableValue> installable)
     {
         auto shellOutPath = getShellOutPath(store, installable);
 
@@ -481,7 +481,7 @@ struct CmdDevelop : Common, MixEnvironment
           ;
     }
 
-    void run(ref<Store> store, ref<Installable> installable) override
+    void run(ref<Store> store, ref<InstallableValue> installable) override
     {
         auto [buildEnvironment, gcroot] = getBuildEnvironment(store, installable);
 
@@ -605,7 +605,7 @@ struct CmdPrintDevEnv : Common, MixJSON
 
     Category category() override { return catUtility; }
 
-    void run(ref<Store> store, ref<Installable> installable) override
+    void run(ref<Store> store, ref<InstallableValue> installable) override
     {
         auto buildEnvironment = getBuildEnvironment(store, installable).first;