nix3-build: show all FOD errors with `--keep-going`

Basically I'd expect the same behavior as with `nix-build`, i.e.
with `--keep-going` the hash-mismatch error of each failing
fixed-output derivation is shown.

The approach is derived from `Store::buildPaths` (`entry-point.cc`):
instead of throwing the first build-result, check if there are any build
errors and if so, display all of them and throw after that.

Unfortunately, the BuildResult struct doesn't have an `ErrorInfo`
(there's a FIXME for that at least), so I have to construct my own here.
This is a rather cheap bugfix and I decided against touching too many
parts of libstore for that (also I don't know if that's in line with the
ongoing refactoring work).

Closes https://git.lix.systems/lix-project/lix/issues/302

Change-Id: I378ab984fa271e6808c6897c45e0f070eb4c6fac

1 files changed, 39 insertions, 0 deletions

diff --git a/tests/functional/fod-failing.nix b/tests/functional/fod-failing.nix
new file mode 100644
index 000000000..37c04fe12
--- /dev/null
+++ b/tests/functional/fod-failing.nix
@@ -0,0 +1,39 @@
+with import ./config.nix;
+rec {
+  x1 = mkDerivation {
+    name = "x1";
+    builder = builtins.toFile "builder.sh"
+      ''
+        echo $name > $out
+      '';
+    outputHashMode = "recursive";
+    outputHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+  };
+  x2 = mkDerivation {
+    name = "x2";
+    builder = builtins.toFile "builder.sh"
+      ''
+        echo $name > $out
+      '';
+    outputHashMode = "recursive";
+    outputHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+  };
+  x3 = mkDerivation {
+    name = "x3";
+    builder = builtins.toFile "builder.sh"
+      ''
+        echo $name > $out
+      '';
+    outputHashMode = "recursive";
+    outputHash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+  };
+  x4 = mkDerivation {
+    name = "x4";
+    inherit x2 x3;
+    builder = builtins.toFile "builder.sh"
+      ''
+        echo $x2 $x3
+        exit 1
+      '';
+  };
+}