make-derivation: fix position in trace

For a long time now, tracing has been broken in Nixpkgs. So when you
have an eval error you would get something like this:

  error: while evaluating the attribute 'buildInputs' of the derivation 'hello-2.10' at /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:185:11:
  while evaluating 'chooseDevOutputs' at /home/mbauer/nixpkgs/lib/attrsets.nix:474:22, called from undefined position:
  while evaluating 'optionals' at /home/mbauer/nixpkgs/lib/lists.nix:257:5, called from /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:132:17:

This is coming from how Nix handles string context and how
make-derivation messes with the "name" attribute. This commit should
restore the old behavior so you get a nice line number like:

  error: while evaluating the attribute 'buildInputs' of the derivation 'hello-2.10' at /home/mbauer/nixpkgs/pkgs/applications/misc/hello/default.nix:4:3:
  while evaluating 'chooseDevOutputs' at /home/mbauer/nixpkgs/lib/attrsets.nix:474:22, called from undefined position:
  while evaluating 'optionals' at /home/mbauer/nixpkgs/lib/lists.nix:257:5, called from /home/mbauer/nixpkgs/pkgs/stdenv/generic/make-derivation.nix:132:17:

NOTE: This will still be broken for cross compilation due to the
prefixes we are adding to name.

1 files changed, 10 insertions, 12 deletions

diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index c646b6d715bd..90dbb102fae9 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -81,8 +81,6 @@ rec {
     , ... } @ attrs:
 
     let
-      computedName = if name != "" then name else "${attrs.pname}-${attrs.version}";
-
       # TODO(@oxij, @Ericson2314): This is here to keep the old semantics, remove when
       # no package has `doCheck = true`.
       doCheck' = doCheck && stdenv.hostPlatform == stdenv.buildPlatform;
@@ -179,15 +177,15 @@ rec {
            "checkInputs" "installCheckInputs"
            "__impureHostDeps" "__propagatedImpureHostDeps"
            "sandboxProfile" "propagatedSandboxProfile"])
-        // {
-          name = computedName + lib.optionalString
-            # Fixed-output derivations like source tarballs shouldn't get a host
-            # suffix. But we have some weird ones with run-time deps that are
-            # just used for their side-affects. Those might as well since the
-            # hash can't be the same. See #32986.
-            (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix)
-            ("-" + stdenv.hostPlatform.config);
-
+        // (lib.optionalAttrs (stdenv.hostPlatform != stdenv.buildPlatform && !dontAddHostSuffix)) {
+          # Fixed-output derivations like source tarballs shouldn't get a host
+          # suffix. But we have some weird ones with run-time deps that are
+          # just used for their side-affects. Those might as well since the
+          # hash can't be the same. See #32986.
+          name = "${if name != "" then name else "${attrs.pname}-${attrs.version}"}-${stdenv.hostPlatform.config}";
+        } // (lib.optionalAttrs (name == "")) {
+          name = "${attrs.pname}-${attrs.version}";
+        } // {
           builder = attrs.realBuilder or stdenv.shell;
           args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
           inherit stdenv;
@@ -276,7 +274,7 @@ rec {
       meta = {
           # `name` above includes cross-compilation cruft (and is under assert),
           # lets have a clean always accessible version here.
-          name = computedName;
+          name = if name != "" then name else "${attrs.pname}-${attrs.version}";
 
           # If the packager hasn't specified `outputsToInstall`, choose a default,
           # which is the name of `p.bin or p.out or p`;