Adopt typed-throws throughout Subprocess

Remove SubprocessError.UnderlyingError and instead use any Error for the .underlyingError field. This setup allows custom execution closures to throw any error and still be represented by a SubprocessError

Raise macOS CI to 26.0 because we hit a mis-compile issue on 16.3

Author: iCharlesHu

.github/workflows/pull_request.yml

@@ -42,7 +42,7 @@ jobs:
         Invoke-Program swift test -c release
         Invoke-Program swift test --disable-default-traits
       enable_macos_checks: true
-      macos_xcode_versions: '["16.3"]'
+      macos_xcode_versions: '["26.0"]'
       macos_build_command: 'xcrun swift test && xcrun swift test -c release && xcrun swift test --disable-default-traits'
       enable_linux_static_sdk_build: true
       enable_android_sdk_build: true

Sources/Subprocess/API.swift

@@ -275,10 +275,7 @@ extension AsyncBufferSequence {
                 while let first = try await nextCodeUnit() {
                     // Throw if we exceed max line length
                     if case .maxLineLength(let maxLength) = self.bufferingPolicy, buffer.count >= maxLength {
-                        throw SubprocessError(
-                            code: .init(.streamOutputExceedsLimit(maxLength)),
-                            underlyingError: nil
-                        )
+                        throw SubprocessError.outputLimitExceeded(limit: maxLength)
                     }
 
                     buffer.append(first)

Sources/Subprocess/AsyncBufferSequence.swift

@@ -71,10 +71,14 @@ extension AsyncBufferSequence.Buffer {
     ///   the method creates it. The argument is valid only for the duration of the
     ///   closure's execution.
     /// - Returns: The return value of the body closure.
-    public func withUnsafeBytes<ResultType>(
-        _ body: (UnsafeRawBufferPointer) throws -> ResultType
-    ) rethrows -> ResultType {
-        return try self.data.withUnsafeBytes(body)
+    public func withUnsafeBytes<ResultType, Error: Swift.Error>(
+        _ body: (UnsafeRawBufferPointer) throws(Error) -> ResultType
+    ) throws(Error) -> ResultType {
+        do {
+            return try self.data.withUnsafeBytes(body)
+        } catch {
+            throw error as! Error
+        }
     }
 
     #if SubprocessSpan