nix/build: add `--rebuild` option

Occasionally, `nix-build --check` is fairly helpful and I'd like to be
able to use this feature for flakes that need to be built with `nix
build` as well.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/nix/build.cc b/src/nix/build.cc
index 0f7e0e123..bec25d8d8 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -9,6 +9,7 @@ using namespace nix;
 struct CmdBuild : InstallablesCommand, MixDryRun, MixProfile
 {
     Path outLink = "result";
+    BuildMode buildMode = bmNormal;
 
     CmdBuild()
     {
@@ -26,6 +27,12 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixProfile
             .description = "do not create a symlink to the build result",
             .handler = {&outLink, Path("")},
         });
+
+        addFlag({
+            .longName = "rebuild",
+            .description = "Rebuild an already built package locally and compare the result to the existing store-paths.",
+            .handler = {&buildMode, bmCheck},
+        });
     }
 
     std::string description() override
@@ -53,7 +60,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixProfile
 
     void run(ref<Store> store) override
     {
-        auto buildables = build(store, dryRun ? Realise::Nothing : Realise::Outputs, installables);
+        auto buildables = build(store, dryRun ? Realise::Nothing : Realise::Outputs, installables, buildMode);
 
         if (dryRun) return;