add dry-run to oizys cache

pkgs/oizys/src/oizys.nim

@@ -70,8 +70,10 @@ hwylCli:
         ? "jobs when pushing paths"
         * countProcessors()
         - j
+      `dry-run`:
+        ? "don't actually build derivations"
     run:
-      nixBuildWithCache(name, args, service, jobs)
+      nixBuildWithCache(name, args, service, jobs, `dry-run`)
 
     [ci]
     ... "builtin ci"

pkgs/oizys/src/oizys/nix.nim

@@ -312,7 +312,11 @@ proc nixBuildHostDry*(minimal: bool, rest: seq[string]) =
   cmd.addArg "--dry-run"
   cmd.addArgs rest
   let (_, err) =
-    runCmdCaptWithSpinner(cmd, "evaluating derivation for: " & getHosts().join(" ").bb("bold"), {CaptStderr})
+    runCmdCaptWithSpinner(
+      cmd,
+      "evaluating derivation for: " & getHosts().join(" ").bb("bold"),
+      {CaptStderr}
+    )
   let output = parseDryRunOutput err
   display output
 
@@ -373,7 +377,7 @@ proc prettyDerivation*(path: string): BbString =
   drv.name.trunc(maxLen) & " " & drv.hash.bb("faint")
 
 
-proc nixBuildWithCache*(name: string, rest:seq[string], service: string, jobs: int) =
+proc nixBuildWithCache*(name: string, rest:seq[string], service: string, jobs: int, dry: bool) =
   ## build individual derivations not cached and push to cache
   if findExe(service) == "": fatalQuit fmt"is {service} installed?"
   info bbfmt"building and pushing to cache: [b]{name}"
@@ -383,7 +387,9 @@ proc nixBuildWithCache*(name: string, rest:seq[string], service: string, jobs: i
     info "nothing to build"
     quit "exiting...", QuitSuccess
 
-  info fmt("building {drvs.len} derivations:\n") & drvs.mapIt(prettyDerivation(it.drv.outputs["out"].path)).join("\n")
+  info fmt("need to build {drvs.len} derivations:\n") & drvs.mapIt(prettyDerivation("  " & it.drv.outputs["out"].path)).join("\n")
+  if dry:
+    quit "exiting...", QuitSuccess
 
   let results =
     collect: