Disable DocC plugin by default (#240)

Co-authored-by: Karl Tarbe <tarbe@apple.com>

Author: fboemer

Package.resolved

@@ -64,7 +64,6 @@ let package = Package(
         .package(url: "https://github.com/apple/swift-log.git", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-numerics", from: "1.0.0"),
         .package(url: "https://github.com/apple/swift-protobuf", from: "1.31.1"), // Keep version in sync with README
-        .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.1.0"),
     ],
     targets: [
         // Targets are the basic building blocks of a package, defining a module or a test suite.
@@ -300,6 +299,22 @@ if enableBenchmarking {
     ]
 }
 
+// MARK: - DoCC plugin
+
+var enableDocCPlugin: Bool {
+    let benchmarkFlags = "SWIFT_HOMOMORPHIC_ENCRYPTION_ENABLE_DOCCPLUGIN"
+    if let flag = ProcessInfo.processInfo.environment[benchmarkFlags], flag == "1" {
+        return true
+    }
+    return false
+}
+
+if enableDocCPlugin {
+    package.dependencies += [
+        .package(url: "https://github.com/swiftlang/swift-docc-plugin", from: "1.1.0"),
+    ]
+}
+
 // Set the minimum macOS version for the package
 #if canImport(Darwin)
 package.platforms = [

Package.swift

@@ -246,9 +246,9 @@ The documentation can be built from Xcode via `Product -> Build Documentation`.
 ## Command line
 The documentation can be built from command line by running
 ```sh
-swift package generate-documentation
+SWIFT_HOMOMORPHIC_ENCRYPTION_ENABLE_DOCCPLUGIN=1 swift package generate-documentation
 ```
 and previewed by running
 ```sh
-swift package --disable-sandbox preview-documentation --target HomomorphicEncryption
+SWIFT_HOMOMORPHIC_ENCRYPTION_ENABLE_DOCCPLUGIN=1 swift package --disable-sandbox preview-documentation --target HomomorphicEncryption
 ```