* Store user environment manifests as a Nix expression in

$out/manifest.nix rather than as an ATerm.

  (Hm, I thought I committed this two days ago...)

src/nix-env/nix-env.cc

@@ -8,7 +8,6 @@
 #include "help.txt.hh"
 #include "get-drvs.hh"
 #include "attr-path.hh"
-#include "pathlocks.hh"
 #include "common-opts.hh"
 #include "xml-writer.hh"
 #include "store-api.hh"
@@ -193,141 +192,6 @@ static Path getDefNixExprPath()
 }
 
 
-/* Ensure exclusive access to a profile.  Any command that modifies
-   the profile first acquires this lock. */
-static void lockProfile(PathLocks & lock, const Path & profile)
-{
-    lock.lockPaths(singleton<PathSet>(profile),
-        (format("waiting for lock on profile `%1%'") % profile).str());
-    lock.setDeletion(true);
-}
-
-
-/* Optimistic locking is used by long-running operations like `nix-env
-   -i'.  Instead of acquiring the exclusive lock for the entire
-   duration of the operation, we just perform the operation
-   optimistically (without an exclusive lock), and check at the end
-   whether the profile changed while we were busy (i.e., the symlink
-   target changed).  If so, the operation is restarted.  Restarting is
-   generally cheap, since the build results are still in the Nix
-   store.  Most of the time, only the user environment has to be
-   rebuilt. */
-static string optimisticLockProfile(const Path & profile)
-{
-    return pathExists(profile) ? readLink(profile) : "";
-}
-
-
-static bool createUserEnv(EvalState & state, DrvInfos & elems,
-    const Path & profile, bool keepDerivations,
-    const string & lockToken)
-{
-    throw Error("not implemented");
-#if 0
-    /* Build the components in the user environment, if they don't
-       exist already. */
-    PathSet drvsToBuild;
-    foreach (DrvInfos::const_iterator, i, elems)
-        /* Call to `isDerivation' is for compatibility with Nix <= 0.7
-           user environments. */
-        if (i->queryDrvPath(state) != "" &&
-            isDerivation(i->queryDrvPath(state)))
-            drvsToBuild.insert(i->queryDrvPath(state));
-
-    debug(format("building user environment dependencies"));
-    store->buildDerivations(drvsToBuild);
-
-    /* Get the environment builder expression. */
-    Expr envBuilder = parseExprFromFile(state,
-        nixDataDir + "/nix/corepkgs/buildenv"); /* !!! */
-
-    /* Construct the whole top level derivation. */
-    PathSet references;
-    ATermList manifest = ATempty;
-    ATermList inputs = ATempty;
-    foreach (DrvInfos::iterator, i, elems) {
-        /* Create a pseudo-derivation containing the name, system,
-           output path, and optionally the derivation path, as well as
-           the meta attributes. */
-        Path drvPath = keepDerivations ? i->queryDrvPath(state) : "";
-
-        /* Round trip to get rid of "bad" meta values (like
-           functions). */
-        MetaInfo meta = i->queryMetaInfo(state);
-        i->setMetaInfo(meta);
-        
-        ATermList as = ATmakeList5(
-            makeBind(toATerm("type"),
-                makeStr("derivation"), makeNoPos()),
-            makeBind(toATerm("name"),
-                makeStr(i->name), makeNoPos()),
-            makeBind(toATerm("system"),
-                makeStr(i->system), makeNoPos()),
-            makeBind(toATerm("outPath"),
-                makeStr(i->queryOutPath(state)), makeNoPos()), 
-            makeBind(toATerm("meta"),
-                i->attrs->get(toATerm("meta")), makeNoPos()));
-        
-        if (drvPath != "") as = ATinsert(as, 
-            makeBind(toATerm("drvPath"),
-                makeStr(drvPath), makeNoPos()));
-        
-        manifest = ATinsert(manifest, makeAttrs(as));
-        
-        inputs = ATinsert(inputs, makeStr(i->queryOutPath(state)));
-
-        /* This is only necessary when installing store paths, e.g.,
-           `nix-env -i /nix/store/abcd...-foo'. */
-        store->addTempRoot(i->queryOutPath(state));
-        store->ensurePath(i->queryOutPath(state));
-        
-        references.insert(i->queryOutPath(state));
-        if (drvPath != "") references.insert(drvPath);
-    }
-
-    /* Also write a copy of the list of inputs to the store; we need
-       it for future modifications of the environment. */
-    Path manifestFile = store->addTextToStore("env-manifest",
-        atPrint(canonicaliseExpr(makeList(ATreverse(manifest)))), references);
-
-    Expr topLevel = makeCall(envBuilder, makeAttrs(ATmakeList3(
-        makeBind(toATerm("system"),
-            makeStr(thisSystem), makeNoPos()),
-        makeBind(toATerm("derivations"),
-            makeList(ATreverse(manifest)), makeNoPos()),
-        makeBind(toATerm("manifest"),
-            makeStr(manifestFile, singleton<PathSet>(manifestFile)), makeNoPos())
-        )));
-
-    /* Instantiate it. */
-    debug(format("evaluating builder expression `%1%'") % topLevel);
-    DrvInfo topLevelDrv;
-    if (!getDerivation(state, topLevel, topLevelDrv))
-        abort();
-    
-    /* Realise the resulting store expression. */
-    debug(format("building user environment"));
-    store->buildDerivations(singleton<PathSet>(topLevelDrv.queryDrvPath(state)));
-
-    /* Switch the current user environment to the output path. */
-    PathLocks lock;
-    lockProfile(lock, profile);
-
-    Path lockTokenCur = optimisticLockProfile(profile);
-    if (lockToken != lockTokenCur) {
-        printMsg(lvlError, format("profile `%1%' changed while we were busy; restarting") % profile);
-        return false;
-    }
-    
-    debug(format("switching to new user environment"));
-    Path generation = createGeneration(profile, topLevelDrv.queryOutPath(state));
-    switchLink(profile, generation);
-
-    return true;
-#endif
-}
-
-
 static int getPriority(EvalState & state, const DrvInfo & drv)
 {
     MetaValue value = drv.queryMetaInfo(state, "priority");