Moved colorization arguments to SwiftTargetDescription.

Author: Austinate

Sources/Basic/TerminalController.swift

@@ -61,13 +61,18 @@ public final class TerminalController {
     /// Constructs the instance if the stream is a tty.
     public init?(stream: LocalFileOutputByteStream) {
         // Make sure this file stream is tty.
-        guard isatty(fileno(stream.filePointer)) != 0 else {
+        guard TerminalController.isTTY(stream) else {
             return nil
         }
         width = TerminalController.terminalWidth() ?? 80 // Assume default if we are not able to determine.
         self.stream = stream
     }
 
+    /// Checks if passed file stream is tty.
+    public static func isTTY(_ stream: LocalFileOutputByteStream) -> Bool {
+        return isatty(fileno(stream.filePointer)) != 0
+    }
+
     /// Tries to get the terminal width first using COLUMNS env variable and
     /// if that fails ioctl method testing on stdout stream.
     ///

Sources/Build/BuildPlan.swift

@@ -57,14 +57,6 @@ public struct BuildParameters {
     public var swiftCompilerFlags: [String] {
         var flags = self.flags.cCompilerFlags.flatMap({ ["-Xcc", $0] })
         flags += self.flags.swiftCompilerFlags
-
-        let stream = stdoutStream as? LocalFileOutputByteStream
-        let terminalController = stream.flatMap({ TerminalController(stream: $0) })
-        // Add extra flags if stdout is tty
-        if terminalController != nil {
-            flags += ["-Xfrontend", "-color-diagnostics"]
-        }
-
         flags += verbosity.ccArgs
         return flags
     }
@@ -80,6 +72,14 @@ public struct BuildParameters {
     /// If should link the Swift stdlib statically.
     public let shouldLinkStaticSwiftStdlib: Bool
 
+    /// Checks if stdout stream is tty.
+    fileprivate let isTTY: Bool = {
+        guard let stream = stdoutStream as? LocalFileOutputByteStream else {
+            return false
+        }
+        return TerminalController.isTTY(stream)
+    }()
+
     public init(
         dataPath: AbsolutePath,
         configuration: Configuration,
@@ -297,6 +297,11 @@ public final class SwiftTargetDescription {
         args += additionalFlags
         args += moduleCacheArgs
 
+        // Add arguments to colorize output if stdout is tty
+        if buildParameters.isTTY {
+            args += ["-Xfrontend", "-color-diagnostics"]
+        }
+
         // User arguments (from -Xswiftc) should follow generated arguments to allow user overrides
         args += buildParameters.swiftCompilerFlags
         return args