[SwiftIfConfig] Adopt updated APIs to for build configuration handling

Switch to the new `canImport` API that includes TokenSyntax nodes for each
import path, so we can provide better source locations. We no longer need
to stuff a random source location into `CompilerBuildConfiguration`.

Make use of `ConfiguredRegions.isActive(_:)` directly instead of going
through the older entrypoint.

When parser validation is enabled, we currently can end up with duplicated
diagnostics from canImport. This is going to require some requestification
to address.

Author: DougGregor

lib/ASTGen/Sources/ASTGen/ASTGen+CompilerBuildConfiguration.swift

@@ -25,8 +25,6 @@ extension ASTGenVisitor {
   /// produced due to the evaluation.
   func activeClause(in node: IfConfigDeclSyntax) -> IfConfigClauseSyntax? {
     // Determine the active clause.
-    var buildConfiguration = self.buildConfiguration
-    buildConfiguration.conditionLoc = generateSourceLoc(node)
     let (activeClause, diagnostics) = node.activeClause(in: buildConfiguration)
     diagnoseAll(diagnostics)
 

lib/ASTGen/Sources/ASTGen/ASTGen.swift

@@ -98,7 +98,7 @@ struct ASTGenVisitor {
     self.legacyParse = legacyParser
     self.buildConfiguration = CompilerBuildConfiguration(
       ctx: ctx,
-      conditionLoc: BridgedSourceLoc(at: AbsolutePosition(utf8Offset: 0), in: sourceBuffer)
+      sourceBuffer: sourceBuffer
     )
   }
 

lib/ASTGen/Sources/ASTGen/CompilerBuildConfiguration.swift

@@ -20,11 +20,11 @@ import SwiftSyntax
 /// queries.
 struct CompilerBuildConfiguration: BuildConfiguration {
   let ctx: BridgedASTContext
-  var conditionLoc: BridgedSourceLoc
+  let sourceBuffer: UnsafeBufferPointer<UInt8>
 
-  init(ctx: BridgedASTContext, conditionLoc: BridgedSourceLoc) {
+  init(ctx: BridgedASTContext, sourceBuffer: UnsafeBufferPointer<UInt8>) {
     self.ctx = ctx
-    self.conditionLoc = conditionLoc
+    self.sourceBuffer = sourceBuffer
   }
 
   func isCustomConditionSet(name: String) throws -> Bool {
@@ -48,8 +48,11 @@ struct CompilerBuildConfiguration: BuildConfiguration {
     }
   }
 
-  func canImport(importPath: [String], version: CanImportVersion) throws -> Bool {
-    var importPathStr = importPath.joined(separator: ".")
+  func canImport(
+    importPath: [(TokenSyntax, String)],
+    version: CanImportVersion
+  ) throws -> Bool {
+    var importPathStr = importPath.map { $0.1 }.joined(separator: ".")
 
     var versionComponents: [Int]
     let cVersionKind: BridgedCanImportVersion
@@ -71,7 +74,10 @@ struct CompilerBuildConfiguration: BuildConfiguration {
       versionComponents.withUnsafeBufferPointer { versionComponentsBuf in
         ctx.canImport(
           importPath: bridgedImportPathStr,
-          location: conditionLoc,
+          location: BridgedSourceLoc(
+            at: importPath.first!.0.position,
+            in: sourceBuffer
+          ),
           versionKind: cVersionKind,
           versionComponents: versionComponentsBuf.baseAddress,
           numVersionComponents: versionComponentsBuf.count
@@ -165,7 +171,7 @@ public func configuredRegions(
   let sourceFilePtr = sourceFilePtr.bindMemory(to: ExportedSourceFile.self, capacity: 1)
   let configuration = CompilerBuildConfiguration(
     ctx: astContext,
-    conditionLoc: sourceFilePtr.pointee.sourceLoc(at: AbsolutePosition(utf8Offset: 0))
+    sourceBuffer: sourceFilePtr.pointee.buffer
   )
   let regions = sourceFilePtr.pointee.syntax.configuredRegions(in: configuration)
 

lib/ASTGen/Sources/ASTGen/SourceFile.swift

@@ -158,23 +158,19 @@ public func emitParserDiagnostics(
   ) { sourceFile in
     var anyDiags = false
 
-    let diags = ParseDiagnosticsGenerator.diagnostics(
-      for: sourceFile.pointee.syntax
-    )
+    let sourceFileSyntax = sourceFile.pointee.syntax
+    let diags = ParseDiagnosticsGenerator.diagnostics(for: sourceFileSyntax)
 
     let diagnosticEngine = BridgedDiagnosticEngine(raw: diagEnginePtr)
     let buildConfiguration = CompilerBuildConfiguration(
       ctx: ctx,
-      conditionLoc:
-        BridgedSourceLoc(
-        at: AbsolutePosition(utf8Offset: 0),
-        in: sourceFile.pointee.buffer
-      )
+      sourceBuffer: sourceFile.pointee.buffer
     )
 
+    let configuredRegions = sourceFileSyntax.configuredRegions(in: buildConfiguration)
     for diag in diags {
       // If the diagnostic is in an unparsed #if region, don't emit it.
-      if diag.node.isActive(in: buildConfiguration).state == .unparsed {
+      if configuredRegions.isActive(diag.node) == .unparsed {
         continue
       }
 

test/Parse/ConditionalCompilation/can_import_version_missing_user_module_version.swift

@@ -14,11 +14,17 @@ import NoUserModuleVersion
 func testCanImportNoUserModuleVersion() {
 
 #if canImport(NoUserModuleVersion, _version: 113.331) // expected-warning {{cannot find user version number for Swift module 'NoUserModuleVersion'; version number ignored}}
+  // NOTE: Duplicate warning because the canImport request happens twice when parser
+  // validation is enabled.
+  // expected-warning@-3 *{{cannot find user version number for Swift module 'NoUserModuleVersion'; version number ignored}}
   let a = 1 // expected-warning {{initialization of immutable value 'a' was never used; consider replacing with assignment to '_' or removing it}}
 #endif
 
 #if canImport(NoUserModuleVersion, _version: 2) // expected-warning {{cannot find user version number for Swift module 'NoUserModuleVersion'; version number ignored}}
   let b = 1 // expected-warning {{initialization of immutable value 'b' was never used; consider replacing with assignment to '_' or removing it}}
+  // NOTE: Duplicate warning because the canImport request happens twice when parser
+  // validation is enabled.
+  // expected-warning@-4 *{{cannot find user version number for Swift module 'NoUserModuleVersion'; version number ignored}}
 #endif
 
 }