feat: preliminary custom targets

Lake/Build/Index.lean

@@ -165,6 +165,13 @@ the initial set of Lake package facets (e.g., `extraDep`).
   | .package pkg facet =>
     if let some build := packageBuildMap.find? facet then
       build pkg
+    else if let some config := pkg.findTargetConfig? facet then
+      if h : facet = config.name then
+        have : DynamicType PackageData facet (ActiveBuildTarget config.resultType) :=
+          ⟨by simp [h, eq_dynamic_type]⟩
+        mkPackageFacetBuild config.build pkg
+      else
+        error "target's name in the configuration does not match the name it was registered with"
     else
       error s!"do not know how to build package facet `{facet}`"
   | .staticLeanLib lib =>
@@ -179,8 +186,6 @@ the initial set of Lake package facets (e.g., `extraDep`).
     mkTargetBuild ExternLib.sharedFacet do
       let staticTarget := Target.active <| ← lib.static.recBuild
       staticToLeanDynlibTarget staticTarget |>.activate
-  | _ =>
-    error s!"do not know how to build `{info.key}`"
 
 /--
 Recursively build the given info using the Lake build index

Lake/Build/Info.lean

@@ -27,7 +27,6 @@ inductive BuildInfo
 | leanExe (exe : LeanExe)
 | staticExternLib (lib : ExternLib)
 | sharedExternLib (lib : ExternLib)
-| custom (package : Package) (target : WfName) (facet : WfName)
 
 --------------------------------------------------------------------------------
 /-! ## Build Info & Keys                                                      -/
@@ -67,7 +66,6 @@ abbrev BuildInfo.key : (self : BuildInfo) → BuildKey
 | leanExe x => x.buildKey
 | staticExternLib l => l.staticBuildKey
 | sharedExternLib l => l.sharedBuildKey
-| custom p t f => ⟨p.name, t, f⟩
 
 /-! ### Instances for deducing data types of `BuildInfo` keys -/
 

Lake/CLI/Build.lean

@@ -60,7 +60,9 @@ def resolveExeTarget (exe : LeanExe) (facet : String) : Except CliError OpaqueTa
     throw <| CliError.unknownFacet "executable" facet
 
 def resolveTargetInPackage (ws : Workspace) (pkg : Package) (target : Name) (facet : String) : Except CliError OpaqueTarget :=
-  if let some exe := pkg.findLeanExe? target then
+  if let some target := pkg.findTargetConfig? target then
+    return pkg.facet target.name |>.target
+  else if let some exe := pkg.findLeanExe? target then
     resolveExeTarget exe facet
   else if let some lib := pkg.findExternLib? target then
     if facet.isEmpty then
@@ -96,7 +98,9 @@ def resolvePackageTarget (ws : Workspace) (pkg : Package) (facet : String) : Exc
     throw <| CliError.unknownFacet "package" facet
 
 def resolveTargetInWorkspace (ws : Workspace) (spec : String) (facet : String) : Except CliError OpaqueTarget :=
-  if let some exe := ws.findLeanExe? spec.toName then
+  if let some (pkg, target) := ws.findTargetConfig? spec then
+    return pkg.facet target.name |>.target
+  else if let some exe := ws.findLeanExe? spec.toName then
     resolveExeTarget exe facet
   else if let some lib := ws.findExternLib? spec.toName then
     if facet.isEmpty then

Lake/Config/Load.lean

@@ -7,6 +7,7 @@ import Lean.Elab.Frontend
 import Lake.DSL.Attributes
 import Lake.DSL.Extensions
 import Lake.Config.ModuleFacetConfig
+import Lake.Config.TargetConfig
 
 namespace Lake
 open Lean System
@@ -124,6 +125,10 @@ unsafe def loadUnsafe (dir : FilePath) (args : List String := [])
         match env.evalConst ModuleFacetConfig leanOpts declName with
         | .ok config => pure <| OpaqueModuleFacetConfig.mk config
         | .error e => throw <| IO.userError e
+      let opaqueTargetConfigs ← mkTagMap targetAttr fun declName =>
+        match env.evalConst TargetConfig leanOpts declName with
+        | .ok config => pure <| OpaqueTargetConfig.mk config
+        | .error e => throw <| IO.userError e
       let defaultTargets := defaultTargetAttr.ext.getState env |>.toArray
       -- Construct the Package
       if leanLibConfigs.isEmpty && leanExeConfigs.isEmpty && config.defaultFacet ≠ .none then
@@ -132,7 +137,7 @@ unsafe def loadUnsafe (dir : FilePath) (args : List String := [])
       return {
         dir, config, scripts,
         leanLibConfigs, leanExeConfigs, externLibConfigs,
-        opaqueModuleFacetConfigs,
+        opaqueModuleFacetConfigs, opaqueTargetConfigs,
         defaultTargets
       }
     | _ => error s!"configuration file has multiple `package` declarations"

Lake/Config/ModuleFacetConfig.lean

@@ -9,7 +9,7 @@ import Lake.Build.Store
 namespace Lake
 open Lean System
 
-/-- A Module facet's declarative configuration. -/
+/-- A module facet's declarative configuration. -/
 structure ModuleFacetConfig where
   /-- The name of the facet. -/
   facet : WfName

Lake/Config/Opaque.lean

@@ -15,3 +15,6 @@ declare_opaque_type OpaqueWorkspace
 
 /-- Opaque reference to a `ModuleFacetConfig` used for forward declaration. -/
 declare_opaque_type OpaqueModuleFacetConfig
+
+/-- Opaque reference to a `TargetConfig` used for forward declaration. -/
+declare_opaque_type OpaqueTargetConfig

Lake/Config/Package.lean

@@ -263,8 +263,10 @@ structure Package where
   leanExeConfigs : NameMap LeanExeConfig := {}
   /-- External library targets for the package. -/
   externLibConfigs : NameMap ExternLibConfig := {}
-  /-- (Opaque) module facets defined in the package. -/
+  /-- (Opaque references to) module facets defined in the package. -/
   opaqueModuleFacetConfigs : NameMap OpaqueModuleFacetConfig := {}
+  /-- (Opaque references to) targets defined in the package. -/
+  opaqueTargetConfigs : NameMap OpaqueTargetConfig := {}
   /--
   The names of the package's targets to build by default
   (i.e., on a bare `lake build` of the package).

Lake/Config/TargetConfig.lean

@@ -0,0 +1,39 @@
+/-
+Copyright (c) 2022 Mac Malone. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mac Malone
+-/
+import Lake.Build.Info
+import Lake.Build.Store
+
+namespace Lake
+
+/-- A custom target's declarative configuration. -/
+structure TargetConfig where
+  /-- The name of the target. -/
+  name : WfName
+  /-- The type of the target's build result. -/
+  resultType : Type
+  /-- The target's build function. -/
+  build : {m : Type → Type} →
+    [Monad m] → [MonadLift BuildM m] → [MonadBuildStore m] →
+    Package → IndexT m (ActiveBuildTarget resultType)
+  /-- Proof that target's build result is the correctly typed target.-/
+  data_eq_target : PackageData name = ActiveBuildTarget resultType
+
+instance : Inhabited TargetConfig := ⟨{
+  name := &`extraDep
+  resultType := PUnit
+  build := default
+  data_eq_target := eq_dynamic_type
+}⟩
+
+hydrate_opaque_type OpaqueTargetConfig TargetConfig
+
+instance {cfg : TargetConfig}
+: DynamicType PackageData cfg.name (ActiveBuildTarget cfg.resultType) :=
+  ⟨cfg.data_eq_target⟩
+
+/-- Try to find a target configuration in the package with the given name . -/
+def Package.findTargetConfig? (name : Name) (self : Package) : Option TargetConfig :=
+  self.opaqueTargetConfigs.find? name |>.map (·.get)

Lake/Config/Workspace.lean

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Mac Malone
 -/
 import Lean.Util.Paths
+import Lake.Config.TargetConfig
 import Lake.Config.ModuleFacetConfig
 
 open System
@@ -90,6 +91,10 @@ def findExternLib? (name : Name) (self : Workspace) : Option ExternLib :=
 def findModuleFacetConfig? (name : Name) (self : Workspace) : Option ModuleFacetConfig :=
   self.packageArray.findSome? fun pkg => pkg.findModuleFacetConfig? name
 
+/-- Try to find a target configuration in the workspace with the given name. -/
+def findTargetConfig? (name : Name) (self : Workspace) : Option (Package × TargetConfig) :=
+  self.packageArray.findSome? fun pkg => pkg.findTargetConfig? name <&> (⟨pkg, ·⟩)
+
 /-- The `LEAN_PATH` of the workspace. -/
 def oleanPath (self : Workspace) : SearchPath :=
   self.packageList.map (·.oleanDir)

Lake/DSL.lean

@@ -12,3 +12,4 @@ import Lake.DSL.Script
 import Lake.DSL.Require
 import Lake.DSL.Targets
 import Lake.DSL.ModuleFacet
+import Lake.DSL.Target

Lake/DSL/Attributes.lean

@@ -23,13 +23,17 @@ initialize leanExeAttr : TagAttribute ←
 initialize externLibAttr : TagAttribute ←
   registerTagAttribute `externLib "mark a definition as a Lake external library target"
 
+initialize targetAttr : TagAttribute ←
+  registerTagAttribute `target "mark a definition as a custom Lake target"
+
 initialize defaultTargetAttr : TagAttribute ←
   registerTagAttribute `defaultTarget "mark a Lake target as the package's default"
     fun name => do
       let valid ← getEnv <&> fun env =>
         leanLibAttr.hasTag env name ||
         leanExeAttr.hasTag env name ||
-        externLibAttr.hasTag env name
+        externLibAttr.hasTag env name ||
+        targetAttr.hasTag env name
       unless valid do
         throwError "attribute `defaultTarget` can only be used on a target (e.g., `lean_lib`, `lean_exe`)"
 

Lake/DSL/DeclUtil.lean

@@ -47,6 +47,9 @@ syntax declValTyped :=
 syntax declValOptTyped :=
   (Term.typeSpec)? declValSimple
 
+syntax simpleDeclSig :=
+  ident Term.typeSpec declValSimple
+
 def expandAttrs (attrs? : Option Attributes) : Array AttrInstance :=
   if let some attrs := attrs? then
     match attrs with

Lake/DSL/ModuleFacet.lean

@@ -9,15 +9,12 @@ import Lake.Config.ModuleFacetConfig
 namespace Lake.DSL
 open Lean Parser Command
 
-syntax moduleFacetDeclSpec :=
-  ident Term.typeSpec declValSimple
-
 scoped macro (name := moduleFacetDecl)
 doc?:optional(docComment) attrs?:optional(Term.attributes)
-"module_facet " spec:moduleFacetDeclSpec : command => do
-  match spec with
-  | `(moduleFacetDeclSpec| $id:ident : $ty := $defn $[$wds?]?) =>
-    let attr ← `(Term.attrInstance| moduleFacet)
+kw:"module_facet " sig:simpleDeclSig : command => do
+  match sig with
+  | `(simpleDeclSig| $id:ident : $ty := $defn $[$wds?]?) =>
+    let attr ← withRef kw `(Term.attrInstance| moduleFacet)
     let attrs := #[attr] ++ expandAttrs attrs?
     let axm := mkIdentFrom id <| ``Lake.ModuleData ++ id.getId
     `(module_data $id : ActiveBuildTarget $ty

Lake/DSL/Target.lean

@@ -0,0 +1,27 @@
+/-
+Copyright (c) 2022 Mac Malone. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Mac Malone
+-/
+import Lake.DSL.DeclUtil
+import Lake.Config.TargetConfig
+
+namespace Lake.DSL
+open Lean Parser Command
+
+scoped macro (name := targetDecl)
+doc?:optional(docComment) attrs?:optional(Term.attributes)
+kw:"target " sig:simpleDeclSig : command => do
+  match sig with
+  | `(simpleDeclSig| $id:ident : $ty := $defn $[$wds?]?) =>
+    let attr ← withRef kw `(Term.attrInstance| target)
+    let attrs := #[attr] ++ expandAttrs attrs?
+    let axm := mkIdentFrom id <| ``Lake.PackageData ++ id.getId
+    `(package_data $id : ActiveBuildTarget $ty
+      $[$doc?]? @[$attrs,*] def $id : TargetConfig := {
+        name := $(WfName.quoteFrom id (WfName.ofName id.getId))
+        resultType := $ty
+        build := $defn
+        data_eq_target := $axm
+      })
+  | stx => Macro.throwErrorAt stx "ill-formed target declaration"

examples/targets/lakefile.lean

@@ -15,3 +15,12 @@ lean_exe b
 
 @[defaultTarget]
 lean_exe c
+
+@[defaultTarget]
+target meow : PUnit := fun pkg => do
+  IO.FS.writeFile (pkg.buildDir / "meow.txt") "Meow!"
+  return ActiveTarget.nil
+
+target bark : PUnit := fun _ => do
+  logInfo "Bark!"
+  return ActiveTarget.nil

examples/targets/test.sh

@@ -1,9 +1,8 @@
-set -e
+#!/usr/bin/env bash
+set -exo pipefail
 
 LAKE=${LAKE:-../../build/bin/lake}
 
-set -x
-
 if [ "$OS" = Windows_NT ]; then
 SHARED_LIB_EXT=dll
 elif [ "`uname`" = Darwin ]; then
@@ -14,6 +13,8 @@ fi
 
 ./clean.sh
 
+$LAKE build bark | grep -m1 Bark!
+
 $LAKE build +Foo.Test
 
 test -f ./build/lib/Foo/Test.olean
@@ -27,6 +28,7 @@ $LAKE build
 
 ./build/bin/c
 test -f ./build/lib/Foo.olean
+cat ./build/meow.txt | grep -m1 Meow!
 
 $LAKE build a b
 
@@ -38,3 +40,5 @@ $LAKE build bar:shared
 
 test -f ./build/lib/libFoo.a
 test -f ./build/lib/Bar.$SHARED_LIB_EXT
+
+$LAKE build bark | grep -m1 Bark!