Add option to skip building and running plugins

This *shouldn't* be needed, but allows running plugins to be skipped if
there's any unexpected interactions with background indexing.

(cherry picked from commit 5f25d6a)

Author: bnbarham

Documentation/Configuration File.md

@@ -27,6 +27,7 @@ The structure of the file is currently not guaranteed to be stable. Options may
   - `linkerFlags: string[]`: Extra arguments passed to the linker. Equivalent to SwiftPM's `-Xlinker` option.
   - `buildToolsSwiftCompilerFlags: string[]`: Extra arguments passed to the compiler for Swift files or plugins. Equivalent to SwiftPM's `-Xbuild-tools-swiftc` option.
   - `disableSandbox: boolean`: Disables running subprocesses from SwiftPM in a sandbox. Equivalent to SwiftPM's `--disable-sandbox` option. Useful when running `sourcekit-lsp` in a sandbox because nested sandboxes are not supported.
+  - `skipPlugins: boolean`: Whether to skip building and running plugins when creating the in-memory build graph. Note: this should generally not be enabled as it will cause generated files not to be found in semantic functionality. It exists only as an escape hatch if doing so causes any unintentional interactions with background indexing.
 - `compilationDatabase`: Dictionary with the following keys, defining options for workspaces with a compilation database.
   - `searchPaths: string[]`: Additional paths to search for a compilation database, relative to a workspace root.
 - `fallbackBuildSystem`: Dictionary with the following keys, defining options for files that aren't managed by any build system.

Sources/BuildSystemIntegration/SwiftPMBuildSystem.swift

@@ -373,7 +373,7 @@ package actor SwiftPMBuildSystem: BuiltInBuildSystem {
     // We have a whole separate arena if we're performing background indexing. This allows us to also build and run
     // plugins, without having to worry about messing up any regular build state.
     let buildDescription: SourceKitLSPAPI.BuildDescription
-    if isForIndexBuild {
+    if isForIndexBuild && !(options.swiftPMOrDefault.skipPlugins ?? false) {
       let loaded = try await BuildDescription.load(
         destinationBuildParameters: destinationBuildParameters,
         toolsBuildParameters: toolsBuildParameters,

Sources/SKOptions/SourceKitLSPOptions.swift

@@ -76,6 +76,11 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
     /// Useful when running `sourcekit-lsp` in a sandbox because nested sandboxes are not supported.
     public var disableSandbox: Bool?
 
+    /// Whether to skip building and running plugins when creating the in-memory build graph. Note: this should
+    /// generally not be enabled as it will cause generated files not to be found in semantic functionality. It exists
+    /// only as an escape hatch if doing so causes any unintentional interactions with background indexing.
+    public var skipPlugins: Bool?
+
     public init(
       configuration: BuildConfiguration? = nil,
       scratchPath: String? = nil,
@@ -88,7 +93,8 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
       swiftCompilerFlags: [String]? = nil,
       linkerFlags: [String]? = nil,
       buildToolsSwiftCompilerFlags: [String]? = nil,
-      disableSandbox: Bool? = nil
+      disableSandbox: Bool? = nil,
+      skipPlugins: Bool? = nil
     ) {
       self.configuration = configuration
       self.scratchPath = scratchPath
@@ -117,7 +123,8 @@ public struct SourceKitLSPOptions: Sendable, Codable, Equatable {
         swiftCompilerFlags: override?.swiftCompilerFlags ?? base.swiftCompilerFlags,
         linkerFlags: override?.linkerFlags ?? base.linkerFlags,
         buildToolsSwiftCompilerFlags: override?.buildToolsSwiftCompilerFlags ?? base.buildToolsSwiftCompilerFlags,
-        disableSandbox: override?.disableSandbox ?? base.disableSandbox
+        disableSandbox: override?.disableSandbox ?? base.disableSandbox,
+        skipPlugins: override?.skipPlugins ?? base.skipPlugins
       )
     }
   }

config.schema.json

@@ -251,6 +251,11 @@
           "markdownDescription" : "Build artifacts directory path. If nil, the build system may choose a default value. This path can be specified as a relative path, which will be interpreted relative to the project root. Equivalent to SwiftPM's `--scratch-path` option.",
           "type" : "string"
         },
+        "skipPlugins" : {
+          "description" : "Whether to skip building and running plugins when creating the in-memory build graph. Note: this should generally not be enabled as it will cause generated files not to be found in semantic functionality. It exists only as an escape hatch if doing so causes any unintentional interactions with background indexing.",
+          "markdownDescription" : "Whether to skip building and running plugins when creating the in-memory build graph. Note: this should generally not be enabled as it will cause generated files not to be found in semantic functionality. It exists only as an escape hatch if doing so causes any unintentional interactions with background indexing.",
+          "type" : "boolean"
+        },
         "swiftCompilerFlags" : {
           "description" : "Extra arguments passed to the compiler for Swift files. Equivalent to SwiftPM's `-Xswiftc` option.",
           "items" : {