Fix nix print-dev-env with drv paths

Fixes #8309

This regression was because both `CmdDevelop` and `CmdPrintDevEnv` were
switched to be `InstallableValueCommand` subclasses, but only
`CmdDevelop` should have been.

src/libcmd/command-installable-value.hh

@@ -10,7 +10,7 @@ namespace nix {
  * An InstallableCommand where the single positional argument must be an
  * InstallableValue in particular.
  */
-struct InstallableValueCommand : InstallableCommand
+struct InstallableValueCommand : virtual InstallableCommand
 {
     /**
      * Entry point to this command

src/nix/develop.cc

@@ -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 : InstallableValueCommand, MixProfile
+struct Common : virtual InstallableCommand, MixProfile
 {
     std::set<std::string> ignoreVars{
         "BASHOPTS",
@@ -374,7 +374,7 @@ struct Common : InstallableValueCommand, MixProfile
         return res;
     }
 
-    StorePath getShellOutPath(ref<Store> store, ref<InstallableValue> installable)
+    StorePath getShellOutPath(ref<Store> store, ref<Installable> installable)
     {
         auto path = installable->getStorePath();
         if (path && hasSuffix(path->to_string(), "-env"))
@@ -393,7 +393,7 @@ struct Common : InstallableValueCommand, MixProfile
     }
 
     std::pair<BuildEnvironment, std::string>
-    getBuildEnvironment(ref<Store> store, ref<InstallableValue> installable)
+    getBuildEnvironment(ref<Store> store, ref<Installable> installable)
     {
         auto shellOutPath = getShellOutPath(store, installable);
 
@@ -407,7 +407,7 @@ struct Common : InstallableValueCommand, MixProfile
     }
 };
 
-struct CmdDevelop : Common, MixEnvironment
+struct CmdDevelop : virtual InstallableValueCommand, Common, MixEnvironment
 {
     std::vector<std::string> command;
     std::optional<std::string> phase;
@@ -605,7 +605,7 @@ struct CmdPrintDevEnv : Common, MixJSON
 
     Category category() override { return catUtility; }
 
-    void run(ref<Store> store, ref<InstallableValue> installable) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         auto buildEnvironment = getBuildEnvironment(store, installable).first;
 

tests/nix-shell.sh

@@ -98,6 +98,14 @@ nix develop -f "$shellDotNix" shellDrv -c echo foo |& grepQuiet foo
 nix print-dev-env -f "$shellDotNix" shellDrv > $TEST_ROOT/dev-env.sh
 nix print-dev-env -f "$shellDotNix" shellDrv --json > $TEST_ROOT/dev-env.json
 
+# Test with raw drv
+
+nix print-dev-env $(nix-instantiate "$shellDotNix" -A shellDrv.out) > $TEST_ROOT/dev-env2.sh
+nix print-dev-env $(nix-instantiate "$shellDotNix" -A shellDrv.out) --json > $TEST_ROOT/dev-env2.json
+
+diff $TEST_ROOT/dev-env{,2}.sh
+diff $TEST_ROOT/dev-env{,2}.json
+
 # Ensure `nix print-dev-env --json` contains variable assignments.
 [[ $(jq -r .variables.arr1.value[2] $TEST_ROOT/dev-env.json) = '3 4' ]]