From 8fbc8540d3ea540d985b577166a1168d472c2d70 Mon Sep 17 00:00:00 2001
From: Matthew Kenigsberg <matthewkenigsberg@gmail.com>
Date: Mon, 27 Apr 2020 12:17:58 -0600
Subject: [PATCH] use nixpkgs#bashInteractive for dev-shell

---
 src/nix/dev-shell.cc | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/src/nix/dev-shell.cc b/src/nix/dev-shell.cc
index 6b1cf0ffd..d842be79f 100644
--- a/src/nix/dev-shell.cc
+++ b/src/nix/dev-shell.cc
@@ -6,6 +6,9 @@
 #include "derivations.hh"
 #include "affinity.hh"
 #include "progress-bar.hh"
+#include "attr-path.hh"
+#include "eval-cache.hh"
+#include "flake/flake.hh"
 
 #include <regex>
 
@@ -281,6 +284,41 @@ struct CmdDevShell : Common, MixEnvironment
         };
     }
 
+    std::string getBashPath(ref<Store> store)
+    {
+        auto flakeRef = FlakeRef::fromAttrs({{"type","indirect"}, {"id", "nixpkgs"}});
+        auto state = getEvalState();
+        auto lockedFlake = std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlags));
+        auto cache = openEvalCache(*state, lockedFlake, true);
+        auto root = cache->getRoot();
+
+        auto attrPath = "legacyPackages." + settings.thisSystem.get() + ".bashInteractive";
+        auto attr = root->findAlongAttrPath(parseAttrPath(*state, attrPath));
+        if (!attr || !attr->isDerivation()) throw Error("couldn't find bashInteractive derivation");
+
+        auto aDrvPath = attr->getAttr(state->sDrvPath);
+        auto drvPath = store->parseStorePath(aDrvPath->getString());
+        if (!store->isValidPath(drvPath) && !settings.readOnlyMode) {
+            /* The eval cache contains 'drvPath', but the actual path
+            has been garbage-collected. So force it to be
+            regenerated. */
+            aDrvPath->forceValue();
+            if (!store->isValidPath(drvPath))
+                throw Error("don't know how to recreate store derivation '%s'!",
+                    store->printStorePath(drvPath));
+        }
+
+        auto outputName = attr->getAttr(state->sOutputName)->getString();
+        if (outputName == "")
+            throw Error("derivation '%s' lacks an 'outputName' attribute", store->printStorePath(drvPath));
+
+        auto outPath = store->parseStorePath(attr->getAttr(state->sOutPath)->getString());
+
+        store->buildPaths({{drvPath, {outputName}}});
+
+        return store->printStorePath(outPath) + "/bin/bash";
+    }
+
     void run(ref<Store> store) override
     {
         auto [buildEnvironment, gcroot] = getBuildEnvironment(store);
@@ -303,12 +341,11 @@ struct CmdDevShell : Common, MixEnvironment
 
         stopProgressBar();
 
-        auto shell = getEnv("SHELL").value_or("bash");
-
         setEnviron();
         // prevent garbage collection until shell exits
         setenv("NIX_GCROOT", gcroot.data(), 1);
 
+        auto shell = getBashPath(store);
         auto args = Strings{std::string(baseNameOf(shell)), "--rcfile", rcFilePath};
 
         restoreAffinity();