Only link static libraries to executables

Docs/ProjectSpec.md

@@ -296,7 +296,7 @@ A dependency can be one of a 3 types:
 These only applied to `target` and `framework` dependencies.
 
 - [ ] **embed**: **Bool** - Whether to embed the dependency. Defaults to true for application target and false for non application targets.
-- [ ] **link**: **Bool** - Whether to link the dependency. Defaults to true but only static library and dynamic frameworks are linked. This only applies for target dependencies.
+- [ ] **link**: **Bool** - Whether to link the dependency. Defaults to `true` depending on the type of the dependency and the type of the target (e.g. static libraries will only link to executables by default).
 - [ ] **codeSign**: **Bool** - Whether the `codeSignOnCopy` setting is applied when embedding framework. Defaults to true
 - [ ] **removeHeaders**: **Bool** - Whether the `removeHeadersOnCopy` setting is applied when embedding the framework. Defaults to true
 

Sources/ProjectSpec/Dependency.swift

@@ -9,15 +9,15 @@ public struct Dependency: Equatable {
     public var embed: Bool?
     public var codeSign: Bool?
     public var removeHeaders: Bool = true
-    public var link: Bool = true
+    public var link: Bool?
     public var implicit: Bool = false
 
     public init(
         type: DependencyType,
         reference: String,
         embed: Bool? = nil,
         codeSign: Bool? = nil,
-        link: Bool = true,
+        link: Bool? = nil,
         implicit: Bool = false
     ) {
         self.type = type
@@ -53,10 +53,8 @@ extension Dependency: JSONObjectConvertible {
 
         embed = jsonDictionary.json(atKeyPath: "embed")
         codeSign = jsonDictionary.json(atKeyPath: "codeSign")
-
-        if let bool: Bool = jsonDictionary.json(atKeyPath: "link") {
-            link = bool
-        }
+        link = jsonDictionary.json(atKeyPath: "link")
+
         if let bool: Bool = jsonDictionary.json(atKeyPath: "removeHeaders") {
             removeHeaders = bool
         }

Sources/ProjectSpec/Linkage.swift

@@ -0,0 +1,41 @@
+import Foundation
+
+public enum Linkage {
+    case dynamic
+    case `static`
+    case none
+}
+
+extension Target {
+
+    public var defaultLinkage: Linkage {
+        switch type {
+        case .none,
+             .appExtension,
+             .application,
+             .bundle,
+             .commandLineTool,
+             .messagesApplication,
+             .messagesExtension,
+             .ocUnitTestBundle,
+             .stickerPack,
+             .tvExtension,
+             .uiTestBundle,
+             .unitTestBundle,
+             .watchApp,
+             .watchExtension,
+             .watch2App,
+             .watch2Extension,
+             .xcodeExtension,
+             .xpcService:
+            return .none
+        case .framework:
+            // TODO: This should check `MACH_O_TYPE` in case this is a "Static Framework"
+            return .dynamic
+        case .dynamicLibrary:
+            return .dynamic
+        case .staticLibrary:
+            return .static
+        }
+    }
+}

Sources/XcodeGenKit/PBXProjGenerator.swift

@@ -435,7 +435,10 @@ public class PBXProjGenerator {
 
                 dependencies.append(targetDependency.reference)
 
-                if (dependencyTarget.type.isLibrary || dependencyTarget.type.isFramework) && dependency.link {
+                let dependecyLinkage = dependencyTarget.defaultLinkage
+                let shouldLink = dependecyLinkage == .dynamic
+                    || (dependecyLinkage == .static && target.type.isExecutable)
+                if dependency.link ?? shouldLink {
                     let dependencyBuildFile = targetBuildFiles[dependencyTargetName]!
                     let buildFile = createObject(
                         id: dependencyBuildFile.reference + target.name,