Do not automatically add -ObjC flag when integrating Objective-C dependencies

Sources/TuistGenerator/Mappers/ModuleMapMapper.swift

@@ -10,7 +10,6 @@ import TuistSupport
 public final class ModuleMapMapper: GraphMapping { // swiftlint:disable:this type_body_length
     private static let modulemapFileSetting = "MODULEMAP_FILE"
     private static let otherCFlagsSetting = "OTHER_CFLAGS"
-    private static let otherLinkerFlagsSetting = "OTHER_LDFLAGS"
     private static let otherSwiftFlagsSetting = "OTHER_SWIFT_FLAGS"
     private static let headerSearchPaths = "HEADER_SEARCH_PATHS"
 
@@ -82,14 +81,6 @@ public final class ModuleMapMapper: GraphMapping { // swiftlint:disable:this typ
                     mappedSettingsDictionary[Self.headerSearchPaths] = updatedHeaderSearchPaths
                 }
 
-                if let updatedOtherLinkerFlags = Self.updatedOtherLinkerFlags(
-                    targetID: targetID,
-                    oldOtherLinkerFlags: mappedSettingsDictionary[Self.otherLinkerFlagsSetting],
-                    targetToDependenciesMetadata: targetToDependenciesMetadata
-                ) {
-                    mappedSettingsDictionary[Self.otherLinkerFlagsSetting] = updatedOtherLinkerFlags
-                }
-
                 let targetSettings = target.settings ?? Settings(
                     base: [:],
                     configurations: [:],
@@ -277,28 +268,4 @@ public final class ModuleMapMapper: GraphMapping { // swiftlint:disable:this typ
 
         return .array(mappedOtherCFlags)
     }
-
-    private static func updatedOtherLinkerFlags(
-        targetID: TargetID,
-        oldOtherLinkerFlags: SettingsDictionary.Value?,
-        targetToDependenciesMetadata: [TargetID: Set<DependencyMetadata>]
-    ) -> SettingsDictionary.Value? {
-        guard let dependenciesModuleMaps = targetToDependenciesMetadata[targetID]?.compactMap(\.moduleMapPath),
-              !dependenciesModuleMaps.isEmpty
-        else { return nil }
-
-        var mappedOtherLinkerFlags: [String]
-        switch oldOtherLinkerFlags ?? .array(["$(inherited)"]) {
-        case let .array(values):
-            mappedOtherLinkerFlags = values
-        case let .string(value):
-            mappedOtherLinkerFlags = value.split(separator: " ").map(String.init)
-        }
-
-        if !mappedOtherLinkerFlags.contains("-ObjC") {
-            mappedOtherLinkerFlags.append("-ObjC")
-        }
-
-        return .array(mappedOtherLinkerFlags)
-    }
 }

Tests/TuistGeneratorTests/ProjectMappers/ModuleMapMapperTests.swift

@@ -114,7 +114,6 @@ final class ModuleMapMapperTests: TuistUnitTestCase {
                     "-fmodule-map-file=$(SRCROOT)/../B/B2/B2.module",
                 ]),
                 "HEADER_SEARCH_PATHS": .array(["$(inherited)", "$(SRCROOT)/../B/B1/include", "$(SRCROOT)/../B/B2/include"]),
-                "OTHER_LDFLAGS": .array(["$(inherited)", "-ObjC"]),
             ]),
             dependencies: [
                 .project(target: "B1", path: projectBPath),
@@ -134,7 +133,6 @@ final class ModuleMapMapperTests: TuistUnitTestCase {
                 "OTHER_CFLAGS": .array(["$(inherited)", "-fmodule-map-file=$(SRCROOT)/B2/B2.module"]),
                 "OTHER_SWIFT_FLAGS": .array(["$(inherited)", "-Xcc", "-fmodule-map-file=$(SRCROOT)/B2/B2.module"]),
                 "HEADER_SEARCH_PATHS": .array(["$(SRCROOT)/B1/include", "$(SRCROOT)/B2/include"]),
-                "OTHER_LDFLAGS": .array(["$(inherited)", "-ObjC"]),
             ]),
             dependencies: [
                 .target(name: "B2"),
@@ -262,7 +260,6 @@ final class ModuleMapMapperTests: TuistUnitTestCase {
                         "-fmodule-map-file=$(SRCROOT)/../B/B/B.module",
                     ]),
                     "HEADER_SEARCH_PATHS": .array(["$(inherited)", "$(SRCROOT)/../B/B/include"]),
-                    "OTHER_LDFLAGS": .array(["$(inherited)", "-ObjC"]),
                 ],
                 configurations: [:],
                 defaultSettings: .recommended

docs/docs/guide/project/dependencies.md

@@ -194,3 +194,11 @@ pod install
 
 > [!WARNING] 
 > CocoaPods dependencies are not compatible with workflows like `build` or `test` that run `xcodebuild` right after generating the project. They are also incompatible with binary caching and selective testing since the fingerprinting logic doesn't account for the Pods dependencies.
+
+## Objective-C Dependencies
+
+When integrating Objective-C dependencies, the inclusion of certain flags on the consuming target may be necessary to avoid runtime crashes as detailed in [Apple Technical Q&A QA1490](https://developer.apple.com/library/archive/qa/qa1490/_index.html).
+
+Since the build system and Tuist have no way of inferring whether the flag is necessary or not, and since the flag comes with potentially undesirable side effects, Tuist will not automatically apply any of these flags, and because Swift Package Manager considers `-ObjC` to be included via an `.unsafeFlag` most packages cannot include it as part of their default linking settings when required.
+
+Consumers of Objective-C dependencies (or internal Objective-C targets) should apply  `-ObjC` or `-force_load` flags when required by setting `OTHER_LDFLAGS` on consuming targets.

fixtures/app_with_spm_dependencies/App/Sources/AppKit/AppKit.swift

@@ -32,7 +32,7 @@ public enum AppKit {
         _ = YAMLEncoder()
 
         // Use GoogleSignIn
-        _ = GIDSignIn.sharedInstance.hasPreviousSignIn()
+        _ = GIDSignIn.sharedInstance.configuration
 
         // Use Sentry
         SentrySDK.startSession()