Allow running tests on Windows by using SWIFTSYNTAX_BUILD_DYNAMIC_LIBRARY

Also, fix two minor Windows test failures.

Author: ahoppen

CONTRIBUTING.md

@@ -38,16 +38,20 @@ $ swift build -Xcxx -I/usr/lib/swift -Xcxx -I/usr/lib/swift/Block
 
 ### Windows
 
-You must provide the following dependencies for SourceKit-LSP:
-- SQLite3 ninja
+To build SourceKit-LSP on Windows, the swift-syntax libraries need to be built as dynamic libraries so we do not exceed the maximum symbol limit in a single binary. Additionally, the equivalent search paths to the linux build need to be passed. Run the following in Command Prompt.
 
 ```cmd
-> swift build -Xcc -I<absolute path to SQLite header search path> -Xlinker -L<absolute path to SQLite library search path> -Xcc -I%SDKROOT%\usr\include -Xcc -I%SDKROOT%\usr\include\Block
+> set SWIFTSYNTAX_BUILD_DYNAMIC_LIBRARY=1
+> swift build -Xcc -I%SDKROOT%\usr\include -Xcc -I%SDKROOT%\usr\include\Block
 ```
 
-The header and library search paths must be passed to the build by absolute path. This allows the clang importer and linker to find the dependencies.
+To work on SourceKit-LSP in VS Code, add the following to your `settings.json`, for other editors ensure that the `SWIFTSYNTAX_BUILD_DYNAMIC_LIBRARY` environment variable is set when launching `sourcekit-lsp`.
 
-Additionally, as SourceKit-LSP depends on libdispatch and the Blocks runtime, which are part of the SDK, but not in the default search path, need to be explicitly added.
+```json
+"swift.swiftEnvironmentVariables": {
+  "SWIFTSYNTAX_BUILD_DYNAMIC_LIBRARY": "1"
+},
+```
 
 ### Devcontainer
 

Package.swift

@@ -128,11 +128,8 @@ let package = Package(
         "SwiftExtensions",
         "ToolchainRegistry",
         .product(name: "ArgumentParser", package: "swift-argument-parser"),
-        .product(name: "SwiftIDEUtils", package: "swift-syntax"),
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
-        .product(name: "SwiftParser", package: "swift-syntax"),
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
-      ],
+      ] + swiftSyntaxDependencies(["SwiftIDEUtils", "SwiftSyntax", "SwiftParser"]),
       exclude: ["CMakeLists.txt"],
       swiftSettings: globalSwiftSettings
     ),
@@ -360,17 +357,14 @@ let package = Package(
         "SwiftExtensions",
         "ToolchainRegistry",
         .product(name: "IndexStoreDB", package: "indexstore-db"),
-        .product(name: "SwiftBasicFormat", package: "swift-syntax"),
         .product(name: "Crypto", package: "swift-crypto"),
-        .product(name: "SwiftDiagnostics", package: "swift-syntax"),
-        .product(name: "SwiftIDEUtils", package: "swift-syntax"),
-        .product(name: "SwiftParser", package: "swift-syntax"),
-        .product(name: "SwiftParserDiagnostics", package: "swift-syntax"),
-        .product(name: "SwiftRefactor", package: "swift-syntax"),
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
         .product(name: "SwiftPM-auto", package: "swift-package-manager"),
-      ],
+      ]
+        + swiftSyntaxDependencies([
+          "SwiftBasicFormat", "SwiftDiagnostics", "SwiftIDEUtils", "SwiftParser", "SwiftParserDiagnostics",
+          "SwiftRefactor", "SwiftSyntax",
+        ]),
       exclude: ["CMakeLists.txt"],
       swiftSettings: globalSwiftSettings
     ),
@@ -391,14 +385,10 @@ let package = Package(
         "ToolchainRegistry",
         .product(name: "IndexStoreDB", package: "indexstore-db"),
         .product(name: "ISDBTestSupport", package: "indexstore-db"),
-        .product(name: "SwiftParser", package: "swift-syntax"),
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
         .product(name: "SwiftToolsSupport-auto", package: "swift-tools-support-core"),
         // Depend on `SwiftCompilerPlugin` and `SwiftSyntaxMacros` so the modules are built before running tests and can
-        // be used by test cases that test macros (see `SwiftPMTestProject.macroPackageManifest`).
-        .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
-        .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
-      ],
+        // be used by test cases that test macros (see `SwiftPMTestProject.macroPackageManifest`)
+      ] + swiftSyntaxDependencies(["SwiftParser", "SwiftSyntax", "SwiftCompilerPlugin", "SwiftSyntaxMacros"]),
       swiftSettings: globalSwiftSettings
     ),
 
@@ -440,6 +430,14 @@ let package = Package(
   swiftLanguageVersions: [.v5, .version("6")]
 )
 
+func swiftSyntaxDependencies(_ names: [String]) -> [Target.Dependency] {
+  if buildDynamicSwiftSyntaxLibrary {
+    return [.product(name: "_SwiftSyntaxDynamic", package: "swift-syntax")]
+  } else {
+    return names.map { .product(name: $0, package: "swift-syntax") }
+  }
+}
+
 // MARK: - Parse build arguments
 
 func hasEnvironmentVariable(_ name: String) -> Bool {
@@ -460,6 +458,13 @@ var installAction: Bool { hasEnvironmentVariable("SOURCEKIT_LSP_CI_INSTALL") }
 /// remote dependency.
 var useLocalDependencies: Bool { hasEnvironmentVariable("SWIFTCI_USE_LOCAL_DEPS") }
 
+/// Whether swift-syntax is being built as a single dynamic library instead of as a separate library per module.
+///
+/// This means that the swift-syntax symbols don't need to be statically linked, which allows us to stay below the
+/// maximum number of exported symbols on Windows, in turn allowing us to build sourcekit-lsp using SwiftPM on Windows
+/// and run its tests.
+var buildDynamicSwiftSyntaxLibrary: Bool { hasEnvironmentVariable("SWIFTSYNTAX_BUILD_DYNAMIC_LIBRARY") }
+
 // MARK: - Dependencies
 
 // When building with the swift build-script, use local dependencies whose contents are controlled

Tests/SourceKitLSPTests/PullDiagnosticsTests.swift

@@ -17,6 +17,10 @@ import SourceKitLSP
 import SwiftExtensions
 import XCTest
 
+#if os(Windows)
+import WinSDK
+#endif
+
 final class PullDiagnosticsTests: XCTestCase {
   func testUnknownIdentifierDiagnostic() async throws {
     let testClient = try await TestSourceKitLSPClient()
@@ -309,7 +313,11 @@ final class PullDiagnosticsTests: XCTestCase {
         if Task.isCancelled {
           break
         }
-        usleep(10_000)
+        #if os(Windows)
+        Sleep(10 /*ms*/)
+        #else
+        usleep(10_000 /*µs*/)
+        #endif
       }
     }
     let project = try await SwiftPMTestProject(

Tests/SourceKitLSPTests/SwiftInterfaceTests.swift

@@ -34,7 +34,7 @@ final class SwiftInterfaceTests: XCTestCase {
       )
     )
     let location = try XCTUnwrap(resp?.locations?.only)
-    XCTAssertTrue(location.uri.pseudoPath.hasSuffix("/Foundation.swiftinterface"))
+    XCTAssertTrue(location.uri.pseudoPath.hasSuffix("Foundation.swiftinterface"))
     let fileContents = try XCTUnwrap(location.uri.fileURL.flatMap({ try String(contentsOf: $0, encoding: .utf8) }))
     // Sanity-check that the generated Swift Interface contains Swift code
     XCTAssert(