Improve check for unsafe flags (#2853)

We prohibit unsafe flags in package dependencies, but the check was only
looking at targets which are direct dependencies of a product, not
transitive ones.

rdar://problem/66499615

(cherry picked from commit 6f469cf)

Author: neonichu

Sources/PackageGraph/PackageGraphLoader.swift

@@ -541,7 +541,7 @@ private final class ResolvedTargetBuilder: ResolvedBuilder<ResolvedTarget> {
 
     func diagnoseInvalidUseOfUnsafeFlags(_ product: ResolvedProduct) {
         // Diagnose if any target in this product uses an unsafe flag.
-        for target in product.targets {
+        for target in product.recursiveTargetDependencies() {
             let declarations = target.underlyingTarget.buildSettings.assignments.keys
             for decl in declarations {
                 if BuildSettings.Declaration.unsafeSettings.contains(decl) {

Sources/PackageModel/ResolvedModels.swift

@@ -235,6 +235,12 @@ public final class ResolvedProduct: ObjectIdentifierProtocol, CustomStringConver
       // contain Swift code we don't know about as part of this build).
       return targets.contains { $0.underlyingTarget is SwiftTarget }
     }
+
+    /// Returns the recursive target dependencies.
+    public func recursiveTargetDependencies() -> [ResolvedTarget] {
+        let recursiveDependencies = targets.lazy.flatMap { $0.recursiveTargetDependencies() }
+        return Array(Set(targets).union(recursiveDependencies))
+    }
 }
 
 extension ResolvedTarget.Dependency: CustomStringConvertible {

Tests/PackageGraphTests/PackageGraphTests.swift

@@ -880,9 +880,11 @@ class PackageGraphTests: XCTestCase {
     func testUnsafeFlags() throws {
         let fs = InMemoryFileSystem(emptyFiles:
             "/Foo/Sources/Foo/foo.swift",
+            "/Foo/Sources/Foo2/foo.swift",
             "/Bar/Sources/Bar/bar.swift",
             "/Bar/Sources/Bar2/bar.swift",
             "/Bar/Sources/Bar3/bar.swift",
+            "/Bar/Sources/TransitiveBar/bar.swift",
             "<end>"
         )
 
@@ -899,14 +901,16 @@ class PackageGraphTests: XCTestCase {
                     ],
                     targets: [
                         TargetDescription(name: "Foo", dependencies: ["Bar"]),
+                        TargetDescription(name: "Foo2", dependencies: ["TransitiveBar"]),
                     ]),
                 Manifest.createV4Manifest(
                     name: "Bar",
                     path: "/Bar",
                     url: "/Bar",
                     packageKind: .local,
                     products: [
-                        ProductDescription(name: "Bar", targets: ["Bar", "Bar2", "Bar3"])
+                        ProductDescription(name: "Bar", targets: ["Bar", "Bar2", "Bar3"]),
+                        ProductDescription(name: "TransitiveBar", targets: ["TransitiveBar"]),
                     ],
                     targets: [
                         TargetDescription(
@@ -926,14 +930,19 @@ class PackageGraphTests: XCTestCase {
                         TargetDescription(
                             name: "Bar3"
                         ),
+                        TargetDescription(
+                            name: "TransitiveBar",
+                            dependencies: ["Bar2"]
+                        ),
                     ]),
             ]
         )
 
-        XCTAssertEqual(diagnostics.diagnostics.count, 2)
+        XCTAssertEqual(diagnostics.diagnostics.count, 3)
         DiagnosticsEngineTester(diagnostics, ignoreNotes: true) { result in
-            result.check(diagnostic: .contains("the target 'Bar' in product 'Bar' contains unsafe build flags"), behavior: .error)
-            result.check(diagnostic: .contains("the target 'Bar2' in product 'Bar' contains unsafe build flags"), behavior: .error)
+            result.checkUnordered(diagnostic: .contains("the target 'Bar2' in product 'TransitiveBar' contains unsafe build flags"), behavior: .error)
+            result.checkUnordered(diagnostic: .contains("the target 'Bar' in product 'Bar' contains unsafe build flags"), behavior: .error)
+            result.checkUnordered(diagnostic: .contains("the target 'Bar2' in product 'Bar' contains unsafe build flags"), behavior: .error)
         }
     }
 

Tests/WorkspaceTests/WorkspaceTests.swift

@@ -3835,7 +3835,8 @@ final class WorkspaceTests: XCTestCase {
         // We should only see errors about use of unsafe flag in the version-based dependency.
         workspace.checkPackageGraph(roots: ["Foo", "Bar"]) { (graph, diagnostics) in
             DiagnosticsEngineTester(diagnostics, ignoreNotes: true) { result in
-               result.check(diagnostic: .equal("the target 'Baz' in product 'Baz' contains unsafe build flags"), behavior: .error)
+               result.checkUnordered(diagnostic: .equal("the target 'Baz' in product 'Baz' contains unsafe build flags"), behavior: .error)
+               result.checkUnordered(diagnostic: .equal("the target 'Bar' in product 'Baz' contains unsafe build flags"), behavior: .error)
            }
         }
     }