feat: only update deps in configure + don't ignore manifest.json

closes leanprover/lake#59, leanprover/lake#63

Lake/CLI/Help.lean

@@ -24,7 +24,7 @@ COMMANDS:
   new <name>            create a Lean package in a new directory
   init <name>           create a Lean package in the current directory
   build [<targets>...]  configure and build targets
-  configure             download and build dependencies
+  configure             update and build dependencies
   clean                 remove build outputs
   script                manage and run workspace scripts
   serve                 start the Lean language server
@@ -79,10 +79,11 @@ TARGET EXAMPLES:
   :bin                  build the root package's binary
 
 A bare `build` command will build the default facet of the root package.
-Arguments to the `Packager` itself can be specified with `args`."
+Arguments to the `Packager` itself can be specified with `args`.
+Package dependencies are not updated during a build."
 
 def helpConfigure :=
-"Download and build dependencies
+"Update and build dependencies
 
 USAGE:
   lake configure [-- <args>...]
@@ -92,8 +93,12 @@ This command sets up the directory with the package's dependencies
 if specified.
 
 For each (transitive) git dependency, the specified commit is checked out
-into a sub-directory of `depsDir`. If there are dependencies on multiple
-versions of the same package, the version materialized is undefined.
+into a sub-directory of `packagesDir`. Already checked out dependencies are
+updated to the latest version compatible with the package's configuration.
+If there are dependencies on multiple versions of the same package, the
+version materialized is undefined. The specific revision of the resolved
+packages are cached in the `manifest.json` file of the `packagesDir`.
+
 No copy is made of local dependencies."
 
 def helpClean :=

Lake/CLI/Init.lean

@@ -5,6 +5,7 @@ Authors: Gabriel Ebner, Sebastian Ullrich, Mac Malone
 -/
 import Lake.Util.Git
 import Lake.Config.Package
+import Lake.Config.Workspace
 import Lake.Config.Load
 
 namespace Lake
@@ -16,7 +17,10 @@ def toolchainFileName : FilePath :=
 "lean-toolchain"
 
 def gitignoreContents :=
-s!"/{defaultBuildDir}\n/{defaultPackagesDir}\n"
+s!"/{defaultBuildDir}
+/{defaultPackagesDir}/*
+!/{defaultPackagesDir}/{manifestFileName}
+"
 
 def libFileContents :=
   s!"def hello := \"world\""

Lake/CLI/Main.lean

@@ -94,7 +94,7 @@ def loadPkg (args : List String := []) : CliStateM Package := do
   setupLeanSearchPath (← getLeanInstall?) (← getLakeInstall?)
   Package.load dir args (dir / file)
 
-def loadWorkspace (args : List String := []) (updateDeps := true) : CliStateM Workspace := do
+def loadWorkspace (args : List String := []) (updateDeps := false) : CliStateM Workspace := do
   let pkg ← loadPkg args
   let ws := Workspace.ofPackage pkg
   let manifest ← do
@@ -305,7 +305,7 @@ def command : (cmd : String) → CliM PUnit
   runBuildM ws <| build (← takeArgs)
 | "configure" => do
   processOptions lakeOption
-  let ws ← loadWorkspace (← getSubArgs)
+  let ws ← loadWorkspace (← getSubArgs) (updateDeps := true)
   noArgsRem <| runBuildM ws ws.root.buildDepOleans
 | "print-paths" => do
   processOptions lakeOption

Lake/Config/Package.lean

@@ -47,7 +47,7 @@ The `src` of a `Dependency`.
 In Lake, dependency sources currently come into flavors:
 * Local `path`s relative to the package's directory.
 * Remote `git` repositories that are download from a given `url`
-  into the packages's `depsDir`.
+  into the workspace's `packagesDir`.
 -/
 inductive Source where
 | path (dir : FilePath)

README.md

@@ -78,7 +78,7 @@ package hello {
 }
 ```
 
-The next run of `lake build` (or refreshing dependencies in an editor like VSCode) will clone the mathlib repository and build it.
+The next run of `lake build` (or refreshing dependencies in an editor like VSCode) will clone the mathlib repository and build it. Information on the specific revision cloned will then be saved to `manifest.json` in `lean_packages` to enable reproducibility. To update `mathlib` after this, you will need to run `lake configure` -- other commands do not update resolved dependencies.
 
 Further examples of different package configurations can be found in the [`examples`](examples) folder of this repository.