Revert "Filter superfluous diagnostics"

This reverts commit ac8806f since it is no longer needed with more recent Swift compilers.

Author: neonichu

Sources/SPMTestSupport/Observability.swift

@@ -72,14 +72,6 @@ public struct TestingObservability {
 
         // TODO: do something useful with scope
         func handleDiagnostic(scope: ObservabilityScope, diagnostic: Basics.Diagnostic) {
-            // Filter superfluous diagnostics.
-            guard !diagnostic.message.hasPrefix("<unknown>:0: warning: annotation implies no releases") else {
-                return
-            }
-            guard !diagnostic.message.hasPrefix("<unknown>:0: note: add explicit") else {
-                return
-            }
-
             if self.verbose {
                 print(diagnostic.description)
             }

Sources/SPMTestSupport/Toolchain.swift

@@ -111,22 +111,6 @@ extension UserToolchain {
         }
     }
 
-    // This builds a trivial program with `-warnings-as-errors`, if it fails, the compiler in use generates warnings by default and is not suitable for testing warnings as errors behaviors.
-    public func supportsWarningsAsErrors() -> Bool {
-        do {
-            try testWithTemporaryDirectory { tmpPath in
-                let inputPath = tmpPath.appending("best.swift")
-                try localFileSystem.writeFileContents(inputPath, string: "print(\"hello\")")
-                let outputPath = tmpPath.appending("foo")
-                let toolchainPath = self.swiftCompilerPath.parentDirectory.parentDirectory
-                try Process.checkNonZeroExit(arguments: ["/usr/bin/xcrun", "--toolchain", toolchainPath.pathString, "swiftc", inputPath.pathString, "-o", outputPath.pathString, "-warnings-as-errors"])
-            }
-            return true
-        } catch {
-            return false
-        }
-    }
-
     /// Helper function to determine whether we should run SDK-dependent tests.
     public func supportsSDKDependentTests() -> Bool {
         return ProcessInfo.processInfo.environment["SWIFTCI_DISABLE_SDK_DEPENDENT_TESTS"] == nil

Tests/CommandsTests/PackageToolTests.swift

@@ -2407,10 +2407,7 @@ final class PackageToolTests: CommandsTestCase {
             do {
                 let (stdout, stderr) = try SwiftPM.Package.execute(["plugin", "MyPlugin", "--foo", "--help", "--version", "--verbose"], packagePath: packageDir)
                 XCTAssertMatch(stdout, .contains("success"))
-                let filteredStderr = stderr.components(separatedBy: "\n").filter {
-                    !$0.contains("annotation implies no releases") && !$0.contains("note: add explicit")
-                }.joined(separator: "\n")
-                XCTAssertEqual(filteredStderr, "")
+                XCTAssertEqual(stderr, "")
             }
 
             // Check default command arguments

Tests/FunctionalTests/MiscellaneousTests.swift

@@ -665,7 +665,7 @@ class MiscellaneousTestCase: XCTestCase {
     func testRootPackageWithConditionals() throws {
         try fixture(name: "Miscellaneous/RootPackageWithConditionals") { path in
             let (_, stderr) = try SwiftPM.Build.execute(packagePath: path)
-            let errors = stderr.components(separatedBy: .newlines).filter { !$0.contains("[logging] misuse") && !$0.contains("annotation implies no releases") && !$0.contains("note: add explicit") && !$0.isEmpty }
+            let errors = stderr.components(separatedBy: .newlines).filter { !$0.contains("[logging] misuse") && !$0.isEmpty }
             XCTAssertEqual(errors, [], "unexpected errors: \(errors)")
         }
     }

Tests/FunctionalTests/ResourcesTests.swift

@@ -11,7 +11,6 @@
 //===----------------------------------------------------------------------===//
 
 import Basics
-import PackageModel
 import SPMTestSupport
 import XCTest
 
@@ -101,8 +100,6 @@ class ResourcesTests: XCTestCase {
     }
 
     func testSwiftResourceAccessorDoesNotCauseInconsistentImportWarning() throws {
-        try XCTSkipIf(!UserToolchain.default.supportsWarningsAsErrors(), "skipping because test environment doesn't support warnings as errors")
-
         try fixture(name: "Resources/FoundationlessClient/UtilsWithFoundationPkg") { fixturePath in
             XCTAssertBuilds(
                 fixturePath,