Revert "Use libSwiftScan to query supported compiler flags in-process"

Author: DougGregor

Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift

@@ -13,7 +13,7 @@
 import SwiftOptions
 import struct Foundation.Data
 import class Foundation.JSONDecoder
-import struct TSCBasic.Diagnostic
+
 import class TSCBasic.DiagnosticsEngine
 import protocol TSCBasic.FileSystem
 import struct TSCBasic.RelativePath
@@ -56,27 +56,27 @@ extension Toolchain {
  }
 }
 
-extension Diagnostic.Message {
- static func warn_supported_features_frontend_fallback() -> Diagnostic.Message {
- .warning("Fallback to `swift-frontend` for supported compiler features query")
- }
-}
-
 extension Driver {
- static func computeSupportedCompilerArgs(of toolchain: Toolchain,
- hostTriple: Triple,
- parsedOptions: inout ParsedOptions,
- diagnosticsEngine: DiagnosticsEngine,
- fileSystem: FileSystem,
- executor: DriverExecutor, env: [String: String])
+ static func computeSupportedCompilerArgs(of toolchain: Toolchain, hostTriple: Triple,
+ parsedOptions: inout ParsedOptions,
+ diagnosticsEngine: DiagnosticsEngine,
+ fileSystem: FileSystem,
+ executor: DriverExecutor, env: [String: String])
  throws -> Set<String> {
- if let supportedArgs = try querySupportedCompilerArgsInProcess(of: toolchain, hostTriple: hostTriple,
- fileSystem: fileSystem, env: env) {
- return supportedArgs
- }
+ // TODO: Once we are sure libSwiftScan is deployed across supported platforms and architectures
+ // we should deploy it here.
+// let swiftScanLibPath = try Self.getScanLibPath(of: toolchain,
+// hostTriple: hostTriple,
+// env: env)
+//
+// if fileSystem.exists(swiftScanLibPath) {
+// let libSwiftScanInstance = try SwiftScan(dylib: swiftScanLibPath)
+// if libSwiftScanInstance.canQuerySupportedArguments() {
+// return try libSwiftScanInstance.querySupportedArguments()
+// }
+// }
 
- // Fallback: Invoke `swift-frontend -emit-supported-features` and decode the output
- diagnosticsEngine.emit(.warn_supported_features_frontend_fallback())
+ // Invoke `swift-frontend -emit-supported-features`
  let frontendOverride = try FrontendOverride(&parsedOptions, diagnosticsEngine)
  frontendOverride.setUpForTargetInfo(toolchain)
  defer { frontendOverride.setUpForCompilation(toolchain) }
@@ -91,23 +91,6 @@ extension Driver {
  return Set(decodedSupportedFlagList)
  }
 
- static func querySupportedCompilerArgsInProcess(of toolchain: Toolchain,
- hostTriple: Triple,
- fileSystem: FileSystem,
- env: [String: String])
- throws -> Set<String>? {
- let swiftScanLibPath = try Self.getScanLibPath(of: toolchain,
- hostTriple: hostTriple,
- env: env)
- if fileSystem.exists(swiftScanLibPath) {
- let libSwiftScanInstance = try SwiftScan(dylib: swiftScanLibPath)
- if libSwiftScanInstance.canQuerySupportedArguments() {
- return try libSwiftScanInstance.querySupportedArguments()
- }
- }
- return nil
- }
-
  static func computeSupportedCompilerFeatures(of toolchain: Toolchain,
  env: [String: String]) throws -> Set<String> {
  struct FeatureInfo: Codable {