[BuildPlan] Demote pkg-config errors to warnings

Fix fallout from 350745a, these were
always supposed to be warnings and not errors.

<rdar://problem/42743455>

Author: aciidgh

Sources/Build/BuildPlan.swift

@@ -818,7 +818,9 @@ public class BuildPlan {
         if let provider = result.provider, result.couldNotFindConfigFile {
             diagnostics.emit(data: PkgConfigHintDiagnostic(pkgConfigName: result.pkgConfigName, installText: provider.installText))
         } else if let error = result.error {
-            diagnostics.emit(error)
+            diagnostics.emit(
+                data: PkgConfigGenericDiagnostic(error: "\(error)"),
+                location: PkgConfigDiagnosticLocation(pcFile: result.pkgConfigName, target: target.name))
         }
         pkgConfigCache[target] = (result.cFlags, result.libs)
         return pkgConfigCache[target]!
@@ -828,6 +830,28 @@ public class BuildPlan {
     private var pkgConfigCache = [SystemLibraryTarget: (cFlags: [String], libs: [String])]()
 }
 
+struct PkgConfigDiagnosticLocation: DiagnosticLocation {
+    let pcFile: String
+    let target: String
+
+    public var localizedDescription: String {
+        return "'\(target)' \(pcFile).pc"
+    }
+}
+
+public struct PkgConfigGenericDiagnostic: DiagnosticData {
+    public static let id = DiagnosticID(
+        type: PkgConfigGenericDiagnostic.self,
+        name: "org.swift.diags.pkg-config-generic",
+        defaultBehavior: .warning,
+        description: {
+            $0 <<< { $0.error }
+        }
+    )
+
+    let error: String
+}
+
 public struct PkgConfigHintDiagnostic: DiagnosticData {
     public static let id = DiagnosticID(
         type: PkgConfigHintDiagnostic.self,

Sources/PackageLoading/Target+PkgConfig.swift

@@ -164,7 +164,7 @@ func whitelist(pcFile: String, flags: (cFlags: [String], libs: [String])) throws
     let filtered = filter(flags: flags.cFlags, filters: ["-I", "-F"]) +
       filter(flags: flags.libs, filters: ["-L", "-l", "-F", "-framework", "-w"])
     guard filtered.isEmpty else {
-        throw PkgConfigError.nonWhitelistedFlags("Non whitelisted flags found: \(filtered) in pc file \(pcFile)")
+        throw PkgConfigError.nonWhitelistedFlags(filtered.joined(separator: ", "))
     }
 }
 

Sources/Utility/PkgConfig.swift

@@ -12,10 +12,21 @@ import Basic
 import Foundation
 import func POSIX.getenv
 
-public enum PkgConfigError: Swift.Error {
+public enum PkgConfigError: Swift.Error, CustomStringConvertible {
     case couldNotFindConfigFile
     case parsingError(String)
     case nonWhitelistedFlags(String)
+
+    public var description: String {
+        switch self {
+        case .couldNotFindConfigFile:
+            return "couldn't find pc file"
+        case .parsingError(let error):
+            return "parsing error(s): \(error)"
+        case .nonWhitelistedFlags(let flags):
+            return "non whitelisted flag(s): \(flags)"
+        }
+    }
 }
 
 public struct PkgConfigExecutionDiagnostic: DiagnosticData {

Tests/BuildTests/BuildPlanTests.swift

@@ -828,7 +828,7 @@ final class BuildPlanTests: XCTestCase {
         }
     }
 
-    func testPkgConfigError() throws {
+    func testPkgConfigHintDiagnostic() throws {
         let fileSystem = InMemoryFileSystem(emptyFiles:
             "/A/Sources/ATarget/foo.swift",
             "/A/Sources/BTarget/module.modulemap"
@@ -861,6 +861,40 @@ final class BuildPlanTests: XCTestCase {
 
         XCTAssertTrue(diagnostics.diagnostics.contains(where: { ($0.data is PkgConfigHintDiagnostic) }))
     }
+
+    func testPkgConfigGenericDiagnostic() throws {
+        let fileSystem = InMemoryFileSystem(emptyFiles:
+            "/A/Sources/ATarget/foo.swift",
+            "/A/Sources/BTarget/module.modulemap"
+        )
+
+        let diagnostics = DiagnosticsEngine()
+        let graph = loadPackageGraph(root: "/A", fs: fileSystem, diagnostics: diagnostics,
+            manifests: [
+                Manifest.createV4Manifest(
+                    name: "A",
+                    path: "/A",
+                    url: "/A",
+                    targets: [
+                        TargetDescription(name: "ATarget", dependencies: ["BTarget"]),
+                        TargetDescription(
+                            name: "BTarget",
+                            type: .system,
+                            pkgConfig: "BTarget"
+                        )
+                    ]),
+            ]
+        )
+
+        _ = try BuildPlan(buildParameters: mockBuildParameters(),
+            graph: graph, diagnostics: diagnostics, fileSystem: fileSystem)
+
+        let diagnostic = diagnostics.diagnostics.first(where: { ($0.data is PkgConfigGenericDiagnostic) })!
+
+        XCTAssertEqual(diagnostic.localizedDescription, "couldn't find pc file")
+        XCTAssertEqual(diagnostic.behavior, .warning)
+        XCTAssertEqual(diagnostic.location.localizedDescription, "'BTarget' BTarget.pc")
+    }
 }
 
 // MARK:- Test Helpers

Tests/BuildTests/XCTestManifests.swift

@@ -14,7 +14,8 @@ extension BuildPlanTests {
         ("testDynamicProducts", testDynamicProducts),
         ("testExecAsDependency", testExecAsDependency),
         ("testNonReachableProductsAndTargets", testNonReachableProductsAndTargets),
-        ("testPkgConfigError", testPkgConfigError),
+        ("testPkgConfigGenericDiagnostic", testPkgConfigGenericDiagnostic),
+        ("testPkgConfigHintDiagnostic", testPkgConfigHintDiagnostic),
         ("testSwiftCMixed", testSwiftCMixed),
         ("testSystemPackageBuildPlan", testSystemPackageBuildPlan),
         ("testTestModule", testTestModule),

Tests/PackageLoadingTests/PkgConfigTests.swift

@@ -88,7 +88,7 @@ class PkgConfigTests: XCTestCase {
             XCTAssertFalse(result.couldNotFindConfigFile)
             switch result.error {
             case PkgConfigError.nonWhitelistedFlags(let desc)?:
-                XCTAssertEqual(desc, "Non whitelisted flags found: [\"-DBlackListed\"] in pc file Bar")
+                XCTAssertEqual(desc, "-DBlackListed")
             default:
                 XCTFail("unexpected error \(result.error.debugDescription)")
             }

Tests/PackageLoadingTests/WhitelistTests.swift

@@ -28,9 +28,7 @@ final class PkgConfigWhitelistTests: XCTestCase {
         do {
             try whitelist(pcFile: "dummy", flags: (cFlags, libs))
         } catch {
-            XCTAssertEqual("\(error)", """
-                nonWhitelistedFlags("Non whitelisted flags found: [\\"-L/hello\\", \\"-module-name\\", \\"name\\", \\"-werror\\"] in pc file dummy")
-                """)
+            XCTAssertEqual("\(error)", "non whitelisted flag(s): -L/hello, -module-name, name, -werror")
         }
     }
 
@@ -40,9 +38,7 @@ final class PkgConfigWhitelistTests: XCTestCase {
         do {
             try whitelist(pcFile: "dummy", flags: (cFlags, libs))
         } catch {
-            XCTAssertEqual("\(error)", """
-                nonWhitelistedFlags("Non whitelisted flags found: [\\"-L/hello\\", \\"-module-name\\", \\"ok\\", \\"name\\"] in pc file dummy")
-                """)
+            XCTAssertEqual("\(error)", "non whitelisted flag(s): -L/hello, -module-name, ok, name")
         }
     }