perform documentation builds in a different scratch directory than .build/

Author: tayloraswift

.gitignore

@@ -1,4 +1,5 @@
 .build
+.build.*
 .swiftinit
 .testing
 .vscode

Package.resolved

@@ -101,7 +101,7 @@ let package:Package = .init(
         .package(url: "https://github.com/tayloraswift/swift-mongodb", .upToNextMinor(
             from: "0.10.5")),
         .package(url: "https://github.com/tayloraswift/swift-png", .upToNextMinor(
-            from: "4.1.0")),
+            from: "4.2.0")),
 
         .package(url: "https://github.com/apple/swift-atomics", .upToNextMinor(
             from: "1.2.0")),

Package.swift

@@ -0,0 +1,17 @@
+import System
+
+extension SPM
+{
+    @frozen public
+    struct ArtifactDirectory:SystemWorkspace
+    {
+        public
+        let path:FilePath
+
+        @inlinable public
+        init(path:FilePath)
+        {
+            self.path = path
+        }
+    }
+}

Sources/SymbolGraphBuilder/Artifacts/ArtifactError.swift

@@ -0,0 +1,37 @@
+import System
+import TraceableErrors
+
+extension SPM
+{
+    public
+    struct ArtifactError:Error, Sendable
+    {
+        public
+        let underlying:any Error
+        public
+        let path:FilePath
+
+        public
+        init(underlying:any Error, path:FilePath)
+        {
+            self.underlying = underlying
+            self.path = path
+        }
+    }
+}
+extension SPM.ArtifactError:Equatable
+{
+    public static
+    func == (lhs:Self, rhs:Self) -> Bool
+    {
+        lhs.path == rhs.path && lhs.underlying == rhs.underlying
+    }
+}
+extension SPM.ArtifactError:TraceableError
+{
+    public
+    var notes:[String]
+    {
+        ["while processing artifact '\(self.path)'"]
+    }
+}

Sources/SymbolGraphBuilder/Artifacts/Artifacts.swift

@@ -6,7 +6,7 @@ import SymbolGraphs
 import Symbols
 import System
 
-extension Artifacts
+extension SPM.Artifacts
 {
     struct Culture
     {
@@ -29,14 +29,14 @@ extension Artifacts
         }
     }
 }
-extension Artifacts.Culture:Identifiable
+extension SPM.Artifacts.Culture:Identifiable
 {
     var id:Symbol.Module
     {
         self.module.id
     }
 }
-extension Artifacts.Culture
+extension SPM.Artifacts.Culture
 {
     func loadArticles(root:Symbol.FileBase) throws -> [MarkdownSourceFile]
     {
@@ -83,7 +83,7 @@ extension Artifacts.Culture
             }
             catch let error
             {
-                throw ArtifactError.init(underlying: error, path: path)
+                throw SPM.ArtifactError.init(underlying: error, path: path)
             }
         }
     }