From f8713e1287e2641c3d2550f7af1a445c77b8552a Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Thu, 4 Dec 2008 10:40:41 +0000
Subject: [PATCH] * Dirty hack to make nix-push work properly on derivations:
 the   derivation should be a source rather than a derivation dependency of  
 the call to the NAR derivation.  Otherwise the derivation (and all   its
 dependencies) will be built as a side-effect, which may not even   succeed.

---
 scripts/nix-push.in    |  3 +--
 src/libexpr/primops.cc | 31 +++++++++++++++++++++++--------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/scripts/nix-push.in b/scripts/nix-push.in
index c7a0dc668..ba611465c 100644
--- a/scripts/nix-push.in
+++ b/scripts/nix-push.in
@@ -128,7 +128,7 @@ while (<READ>) {
 close READ or die "nix-instantiate failed: $?";
 
 
-# Realise the store expressions.
+# Build the derivations.
 print STDERR "creating archives...\n";
 
 my @narPaths;
@@ -144,7 +144,6 @@ while (scalar @tmp > 0) {
     # reference (see above).  Even if that is fixed, using a hook
     # probably wouldn't make that much sense; pumping lots of data
     # around just to compress them won't gain that much.
-    $ENV{"NIX_BUILD_HOOK"} = "";
     my $pid = open(READ, "$binDir/nix-store --no-build-hook --realise @tmp2|")
         or die "cannot run nix-store";
     while (<READ>) {
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 7d179da8e..989a68682 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -366,12 +366,18 @@ static Expr prim_derivationStrict(EvalState & state, const ATermVector & args)
        attributes should be added as dependencies of the resulting
        derivation. */
     for (PathSet::iterator i = context.begin(); i != context.end(); ++i) {
-        debug(format("derivation uses `%1%'") % *i);
-        assert(isStorePath(*i));
-        if (isDerivation(*i))
-            drv.inputDrvs[*i] = singleton<StringSet>("out");
+        Path path = *i;
+        bool buildDrv = true;
+        if (path.at(0) == '=') {
+            buildDrv = false;
+            path = string(path, 1);
+        }
+        debug(format("derivation uses `%1%'") % path);
+        assert(isStorePath(path));
+        if (buildDrv && isDerivation(path))
+            drv.inputDrvs[path] = singleton<StringSet>("out");
         else
-            drv.inputSrcs.insert(*i);
+            drv.inputSrcs.insert(path);
     }
             
     /* Do we have all required attributes? */
@@ -498,9 +504,17 @@ static Expr prim_storePath(EvalState & state, const ATermVector & args)
     Path path = canonPath(coerceToPath(state, args[0], context));
     if (!isInStore(path))
         throw EvalError(format("path `%1%' is not in the Nix store") % path);
-    if (!store->isValidPath(path))
-        throw EvalError(format("store path `%1%' is not valid") % path);
-    context.insert(toStorePath(path));
+    Path path2 = toStorePath(path);
+    if (!store->isValidPath(path2))
+        throw EvalError(format("store path `%1%' is not valid") % path2);
+    /* If this is a derivation, mark it so it doesn't get built;
+       i.e. we want the dependency as a "source" dependency.  This is
+       to make nix-push work properly (we want it to create a NAR
+       archive of the derivation, not build the derivation as a
+       side-effect).  The `=' is a special marker that gets stripped
+       off by prim_derivationStrict. */
+    if (isDerivation(path2)) path2 = "=" + path2;
+    context.insert(path2);
     return makeStr(path, context);
 }
 
@@ -578,6 +592,7 @@ static Expr prim_toFile(EvalState & state, const ATermVector & args)
     for (PathSet::iterator i = context.begin(); i != context.end(); ++i) {
         if (isDerivation(*i))
             throw EvalError(format("in `toFile': the file `%1%' cannot refer to derivation outputs") % name);
+        /* !!! */
         refs.insert(*i);
     }