[BuildPlan] Add c++ link args if needed

Author: aciidgh

Sources/Build/BuildPlan.swift

@@ -417,9 +417,28 @@ public class BuildPlan {
  for buildProduct in buildProducts {
  // FIXME: Ask this from package graph instead.
  let allModules = try! topologicalSort(buildProduct.product.modules, successors: { $0.dependencies })
- // Add pkgConfig libs arguments.
- for case let module as CModule in allModules {
- buildProduct.additionalFlags += pkgConfig(for: module).libs
+ var linkCpp = false
+
+ for module in allModules {
+ switch module {
+ case let module as CModule:
+ // Add pkgConfig libs arguments.
+ buildProduct.additionalFlags += pkgConfig(for: module).libs
+ case let module as ClangModule:
+ if module.containsCppFiles {
+ linkCpp = true
+ }
+ default: break
+ }
+ }
+ // Link C++ if needed.
+ // Note: This will come from build settings in future.
+ if linkCpp {
+ #if os(macOS)
+ buildProduct.additionalFlags += ["-lc++"]
+ #else
+ buildProduct.additionalFlags += ["-lstdc++"]
+ #endif
  }
  }
  }

Sources/Build/misc.swift

@@ -12,9 +12,6 @@ import Basic
 import Utility
 import PackageModel
 
-import func POSIX.getenv
-import func POSIX.popen
-
 public protocol Toolchain {
  /// Path of the `swiftc` compiler.
  var swiftCompiler: AbsolutePath { get }
@@ -42,30 +39,6 @@ extension AbsolutePath {
 }
 
 extension ClangModule {
- // Returns language specific arguments for a ClangModule.
- var languageLinkArgs: [String] {
- var args = [String]() 
- // Check if this module contains any cpp file.
- var linkCpp = self.containsCppFiles
-
- // Otherwise check if any of its dependencies contains a cpp file.
- // FIXME: It is expensive to iterate over all of the dependencies.
- // Figure out a way to cache this kind of lookups.
- if !linkCpp {
- for case let dep as ClangModule in recursiveDependencies {
- if dep.containsCppFiles {
- linkCpp = true
- break
- }
- }
- }
- // Link C++ if found any cpp source. 
- if linkCpp {
- args += ["-lstdc++"]
- }
- return args
- }
-
  var containsCppFiles: Bool {
  return sources.paths.contains { $0.isCpp }
  }

Tests/BuildTests/BuildPlanTests.swift

@@ -196,13 +196,39 @@ final class BuildPlanTests: XCTestCase {
  XCTAssertEqual(try result.target(for: "exe").swiftTarget().compileArguments(), ["-Onone", "-g", "-enable-testing", "-j8", "-DSWIFT_PACKAGE", "-Xcc", "-fmodule-map-file=/Clibgit/module.modulemap", "-module-cache-path", "/path/to/build/debug/ModuleCache"])
  }
 
+ func testCppModule() throws {
+ let fs = InMemoryFileSystem(emptyFiles:
+ "/Pkg/Sources/exe/main.swift",
+ "/Pkg/Sources/lib/lib.cpp",
+ "/Pkg/Sources/lib/include/lib.h"
+ )
+ let pkg = Package(
+ name: "Pkg",
+ targets: [
+ Target(name: "exe", dependencies: ["lib"]),
+ ]
+ )
+ let graph = try loadMockPackageGraph(["/Pkg": pkg], root: "/Pkg", in: fs)
+ let result = BuildPlanResult(plan: try BuildPlan(buildParameters: mockBuildParameters(), graph: graph, fileSystem: fs))
+ result.checkProductsCount(1)
+ result.checkTargetsCount(2)
+ let linkArgs = try result.buildProduct(for: "exe").linkArguments()
+
+ #if os(macOS)
+ XCTAssertTrue(linkArgs.contains("-lc++"))
+ #else
+ XCTAssertTrue(linkArgs.contains("-lstdc++"))
+ #endif
+ }
+
  static var allTests = [
  ("testBasicClangPackage", testBasicClangPackage),
  ("testBasicReleasePackage", testBasicReleasePackage),
  ("testBasicSwiftPackage", testBasicSwiftPackage),
  ("testCModule", testCModule),
  ("testSwiftCMixed", testSwiftCMixed),
  ("testTestModule", testTestModule),
+ ("testCppModule", testCppModule),
  ]
 }