Clean up the lock file handling flags

Added a flag --no-update-lock-file to barf if the lock file needs any
changes. This is useful for CI systems if you're building a
checkout. Fixes #2947.

Renamed --no-save-lock-file to --no-write-lock-file. It is now a fatal
error if the lock file needs changes but --no-write-lock-file is not
given.

src/nix/command.hh

@@ -16,10 +16,6 @@ class EvalState;
 struct Pos;
 class Store;
 
-namespace flake {
-enum LockFileMode : unsigned int;
-}
-
 /* A command that requires a Nix store. */
 struct StoreCommand : virtual Command
 {
@@ -42,15 +38,9 @@ struct EvalCommand : virtual StoreCommand, MixEvalArgs
 
 struct MixFlakeOptions : virtual Args
 {
-    bool recreateLockFile = false;
-    bool saveLockFile = true;
-    bool useRegistries = true;
-
     flake::LockFlags lockFlags;
 
     MixFlakeOptions();
-
-    flake::LockFileMode getLockFileMode();
 };
 
 struct SourceExprCommand : virtual Args, EvalCommand, MixFlakeOptions

src/nix/flake.cc

@@ -38,12 +38,12 @@ public:
     Flake getFlake()
     {
         auto evalState = getEvalState();
-        return flake::getFlake(*evalState, getFlakeRef(), useRegistries);
+        return flake::getFlake(*evalState, getFlakeRef(), lockFlags.useRegistries);
     }
 
     LockedFlake lockFlake()
     {
-        return flake::lockFlake(*getEvalState(), getFlakeRef(), getLockFileMode(), lockFlags);
+        return flake::lockFlake(*getEvalState(), getFlakeRef(), lockFlags);
     }
 };
 

src/nix/installables.cc

@@ -22,17 +22,22 @@ MixFlakeOptions::MixFlakeOptions()
     mkFlag()
         .longName("recreate-lock-file")
         .description("recreate lock file from scratch")
-        .set(&recreateLockFile, true);
+        .set(&lockFlags.recreateLockFile, true);
 
     mkFlag()
-        .longName("no-save-lock-file")
-        .description("do not save the newly generated lock file")
-        .set(&saveLockFile, false);
+        .longName("no-update-lock-file")
+        .description("do not allow any updates to the lock file")
+        .set(&lockFlags.updateLockFile, false);
+
+    mkFlag()
+        .longName("no-write-lock-file")
+        .description("do not write the newly generated lock file")
+        .set(&lockFlags.writeLockFile, false);
 
     mkFlag()
         .longName("no-registries")
         .description("don't use flake registries")
-        .set(&useRegistries, false);
+        .set(&lockFlags.useRegistries, false);
 
     mkFlag()
         .longName("override-input")
@@ -46,17 +51,6 @@ MixFlakeOptions::MixFlakeOptions()
         });
 }
 
-flake::LockFileMode MixFlakeOptions::getLockFileMode()
-{
-    using namespace flake;
-    return
-        useRegistries
-        ? recreateLockFile
-          ? (saveLockFile ? RecreateLockFile : UseNewLockFile)
-          : (saveLockFile ? UpdateLockFile : UseUpdatedLockFile)
-        : AllPure;
-}
-
 SourceExprCommand::SourceExprCommand()
 {
     mkFlag()
@@ -332,7 +326,7 @@ std::tuple<std::string, FlakeRef, flake::EvalCache::Derivation> InstallableFlake
 {
     auto state = cmd.getEvalState();
 
-    auto lockedFlake = lockFlake(*state, flakeRef, cmd.getLockFileMode(), cmd.lockFlags);
+    auto lockedFlake = lockFlake(*state, flakeRef, cmd.lockFlags);
 
     Value * vOutputs = nullptr;
 
@@ -386,7 +380,7 @@ std::vector<flake::EvalCache::Derivation> InstallableFlake::toDerivations()
 
 Value * InstallableFlake::toValue(EvalState & state)
 {
-    auto lockedFlake = lockFlake(state, flakeRef, cmd.getLockFileMode(), cmd.lockFlags);
+    auto lockedFlake = lockFlake(state, flakeRef, cmd.lockFlags);
 
     auto vOutputs = getFlakeOutputs(state, lockedFlake);