Make the DWARF version configurable.

This mirrors a similar change in the swift repository.

Author: adrian-prantl

Sources/SwiftDriver/Driver/DebugInfo.swift

@@ -41,9 +41,12 @@
     }
   }
 
-  // The format of debug information.
+  /// The format of debug information.
   public let format: Format
 
+  /// The DWARF standard version to be produced.
+  public let dwarfVersion: UInt8
+
   /// The level of debug information.
   public let level: Level?
 

Sources/SwiftDriver/Driver/Driver.swift

@@ -2308,7 +2308,23 @@ extension Driver {
       diagnosticsEngine.emit(.error_argument_not_allowed_with(arg: fullNotAllowedOption, other: levelOption.spelling))
     }
 
-    return DebugInfo(format: format, level: level, shouldVerify: shouldVerify)
+    // Determine the DWARF version.
+    var dwarfVersion: UInt8 = 4
+    if let versionArg = parsedOptions.getLastArgument(.dwarfVersion) {
+      if let parsedVersion = UInt8(versionArg.asSingle), parsedVersion >= 2 && parsedVersion <= 5 {
+        dwarfVersion = parsedVersion
+      } else {
+        diagnosticsEngine.emit(.error_invalid_arg_value(arg: .dwarfVersion, value: versionArg.asSingle))
+      }
+    }
+
+    if format == .codeView && (level == .lineTables || level == .dwarfTypes) {
+      let levelOption = parsedOptions.getLast(in: .g)!.option
+      let fullNotAllowedOption = Option.debugInfoFormat.spelling + format.rawValue
+      diagnosticsEngine.emit(.error_argument_not_allowed_with(arg: fullNotAllowedOption, other: levelOption.spelling))
+    }
+      
+    return DebugInfo(format: format, dwarfVersion: dwarfVersion, level: level, shouldVerify: shouldVerify)
   }
 
   /// Parses the set of `-sanitize={sanitizer}` arguments and returns all the

Sources/SwiftDriver/Jobs/FrontendJobHelpers.swift

@@ -193,6 +193,7 @@ extension Driver {
     try commandLine.appendLast(.enablePrivateImports, from: &parsedOptions)
     try commandLine.appendLast(in: .g, from: &parsedOptions)
     try commandLine.appendLast(.debugInfoFormat, from: &parsedOptions)
+    try commandLine.appendLast(.dwarfVersion, from: &parsedOptions)
     try commandLine.appendLast(.importUnderlyingModule, from: &parsedOptions)
     try commandLine.appendLast(.moduleCachePath, from: &parsedOptions)
     try commandLine.appendLast(.moduleLinkName, from: &parsedOptions)

Sources/SwiftOptions/Options.swift

@@ -109,6 +109,7 @@ extension Option {
   public static let debugForbidTypecheckPrefix: Option = Option("-debug-forbid-typecheck-prefix", .separate, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Triggers llvm fatal_error if typechecker tries to typecheck a decl with the provided prefix name")
   public static let debugGenericSignatures: Option = Option("-debug-generic-signatures", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Debug generic signatures")
   public static let debugInfoFormat: Option = Option("-debug-info-format=", .joined, attributes: [.frontend], helpText: "Specify the debug info format type to either 'dwarf' or 'codeview'")
+  public static let dwarfVersion: Option = Option("-dwarf-version=", .joined, attributes: [.frontend], helpText: "DWARF debug info version to produce if requested")
   public static let debugInfoStoreInvocation: Option = Option("-debug-info-store-invocation", .flag, attributes: [.frontend], helpText: "Emit the compiler invocation in the debug info.")
   public static let debugMapping: Option = Option("-debug-mapping", .flag, attributes: [.noDriver], helpText: "Dumping information for debug purposes")
   public static let debugMapping_: Option = Option("--debug-mapping", .flag, alias: Option.debugMapping, attributes: [.noDriver], helpText: "Dumping information for debug purposes")
@@ -907,6 +908,7 @@ extension Option {
       Option.debugForbidTypecheckPrefix,
       Option.debugGenericSignatures,
       Option.debugInfoFormat,
+      Option.dwarfVersion,
       Option.debugInfoStoreInvocation,
       Option.debugMapping,
       Option.debugMapping_,

Tests/SwiftDriverTests/SwiftDriverTests.swift

@@ -574,6 +574,19 @@ final class SwiftDriverTests: XCTestCase {
       $1.expect(.error("argument '-debug-info-format=codeview' is not allowed with '-gdwarf-types'"))
     }
 
+    try assertDriverDiagnostics(args: "swiftc", "foo.swift", "-emit-module", "-dwarf-version=0") {
+      $1.expect(.error("invalid value '0' in '-dwarf-version="))
+    }
+
+    try assertDriverDiagnostics(args: "swiftc", "foo.swift", "-emit-module", "-dwarf-version=6") {
+      $1.expect(.error("invalid value '6' in '-dwarf-version="))
+    }
+
+    try assertNoDriverDiagnostics(args: "swiftc", "foo.swift", "-emit-module", "-g", "-debug-info-format=dwarf", "-dwarf-version=4") { driver in
+        let jobs = try driver.planBuild()
+        XCTAssertTrue(jobs[0].commandLine.contains(.flag("-dwarf-version=4")))
+    }
+
     try assertNoDriverDiagnostics(args: "swiftc", "foo.swift", "-g", "-c", "-file-compilation-dir", ".") { driver in
       let jobs = try driver.planBuild()
       XCTAssertTrue(jobs[0].commandLine.contains(.flag("-file-compilation-dir")))