Update incremental build hash to encode option arguments and ordering

Otherwise, changing the argument to an option which affects incremental builds, or the relative ordering of multiple options affecting incremental builds won't correctly rebuild all of the sources.

rdar://96556787

Author: owenv

Sources/SwiftDriver/IncrementalCompilation/BuildRecordInfo.swift

@@ -109,8 +109,7 @@ import SwiftOptions
     var parsedOptions = parsedOptionsArg
     let hashInput = parsedOptions
       .filter { $0.option.affectsIncrementalBuild && $0.option.kind != .input}
-      .map { $0.option.spelling }
-      .sorted()
+      .map { $0.description } // The description includes the spelling of the option itself and, if present, its argument(s).
       .joined()
     return SHA256().hash(hashInput).hexadecimalRepresentation
   }

Tests/SwiftDriverTests/IncrementalCompilationTests.swift

@@ -537,6 +537,74 @@ extension IncrementalCompilationTests {
   }
 }
 
+// MARK: - Incremental argument hashing tests
+extension IncrementalCompilationTests {
+  func testNullBuildWhenAddingAndRemovingArgumentsNotAffectingIncrementalBuilds() throws {
+    // Adding, removing, or changing the arguments of options which don't affect incremental builds should result in a null build.
+    try buildInitialState(extraArguments: ["-driver-batch-size-limit", "5", "-debug-diagnostic-names"])
+    let driver = try checkNullBuild(extraArguments: ["-driver-batch-size-limit", "10", "-diagnostic-style", "swift"])
+    let mandatoryJobs = try XCTUnwrap(driver.incrementalCompilationState?.mandatoryJobsInOrder)
+    XCTAssertTrue(mandatoryJobs.isEmpty)
+  }
+
+  func testChangingOptionArgumentLeadsToRecompile() throws {
+    // If an option affects incremental builds, changing only the argument should trigger a full recompile.
+    try buildInitialState(extraArguments: ["-user-module-version", "1.0"])
+    try doABuild(
+      "change user module version",
+      checkDiagnostics: true,
+      extraArguments: ["-user-module-version", "1.1"],
+      whenAutolinking: autolinkLifecycleExpectedDiags
+    ) {
+      enablingCrossModule
+      differentArgsPassed
+      disablingIncrementalDifferentArgsPassed
+      createdGraphFromSwiftdeps
+      findingBatchingCompiling("main", "other")
+      reading(deps: "main", "other")
+      schedLinking
+    }
+  }
+
+  func testOptionReorderingLeadsToRecompile() throws {
+    // Reordering options which affect incremental builds should trigger a full recompile.
+    try buildInitialState(extraArguments: ["-warnings-as-errors", "-no-warnings-as-errors"])
+    try doABuild(
+      "change user module version",
+      checkDiagnostics: true,
+      extraArguments: ["-no-warnings-as-errors", "-warnings-as-errors"],
+      whenAutolinking: autolinkLifecycleExpectedDiags
+    ) {
+      enablingCrossModule
+      differentArgsPassed
+      disablingIncrementalDifferentArgsPassed
+      createdGraphFromSwiftdeps
+      findingBatchingCompiling("main", "other")
+      reading(deps: "main", "other")
+      schedLinking
+    }
+  }
+
+  func testArgumentReorderingLeadsToRecompile() throws {
+    // Reordering the arguments of an option which affect incremental builds should trigger a full recompile.
+    try buildInitialState(extraArguments: ["-Ifoo", "-Ibar"])
+    try doABuild(
+      "change user module version",
+      checkDiagnostics: true,
+      extraArguments: ["-Ibar", "-Ifoo"],
+      whenAutolinking: autolinkLifecycleExpectedDiags
+    ) {
+      enablingCrossModule
+      differentArgsPassed
+      disablingIncrementalDifferentArgsPassed
+      createdGraphFromSwiftdeps
+      findingBatchingCompiling("main", "other")
+      reading(deps: "main", "other")
+      schedLinking
+    }
+  }
+}
+
 // MARK: - Incremental test stages
 extension IncrementalCompilationTests {
   /// Setup the initial post-build state.
@@ -1390,6 +1458,12 @@ extension DiagVerifiable {
   @DiagsBuilder var disablingIncrementalCannotReadBuildRecord: [Diagnostic.Message] {
     "Incremental compilation: Disabling incremental build: could not read build record"
   }
+  @DiagsBuilder var differentArgsPassed: [Diagnostic.Message] {
+      "Incremental compilation: Incremental compilation has been disabled, because different arguments were passed to the compiler"
+  }
+  @DiagsBuilder var disablingIncrementalDifferentArgsPassed: [Diagnostic.Message] {
+      "Incremental compilation: Disabling incremental build: different arguments were passed to the compiler"
+  }
   @DiagsBuilder var missingMainDependencyEntry: [Diagnostic.Message] {
     .warning("ignoring -incremental; output file map has no master dependencies entry (\"swift-dependencies\" under \"\")")
   }