Remove "unsafe" keyword from expressions when printing inlinable code

lib/ASTGen/Sources/ASTGen/CompilerBuildConfiguration.swift

@@ -13,8 +13,8 @@
 import ASTBridging
 import SwiftDiagnostics
 @_spi(Compiler) import SwiftIfConfig
-import SwiftParser
-import SwiftSyntax
+@_spi(ExperimentalLanguageFeatures) import SwiftParser
+@_spi(ExperimentalLanguageFeatures) import SwiftSyntax
 
 /// A build configuration that uses the compiler's ASTContext to answer
 /// queries.
@@ -517,7 +517,11 @@ public func extractInlinableText(
   sourceText: BridgedStringRef
 ) -> BridgedStringRef {
   let textBuffer = UnsafeBufferPointer<UInt8>(start: sourceText.data, count: sourceText.count)
-  var parser = Parser(textBuffer)
+  var parser = Parser(
+    textBuffer,
+    swiftVersion: Parser.SwiftVersion(from: astContext),
+    experimentalFeatures: Parser.ExperimentalFeatures(from: astContext)
+  )
   let syntax = SourceFileSyntax.parse(from: &parser)
 
   let configuration = CompilerBuildConfiguration(
@@ -531,6 +535,24 @@ public func extractInlinableText(
     retainFeatureCheckIfConfigs: true
   ).result
 
+  // Remove "unsafe" expressions.
+  let inlineableSyntax = syntaxWithoutInactive.withoutUnsafeExpressions
+
   // Remove comments and return the result.
-  return allocateBridgedString(syntaxWithoutInactive.descriptionWithoutCommentsAndSourceLocations)
+  return allocateBridgedString(inlineableSyntax.descriptionWithoutCommentsAndSourceLocations)
+}
+
+/// Used by withoutUnsafeExpressions to remove "unsafe" expressions from
+/// a syntax tree.
+fileprivate class RemoveUnsafeExprSyntaxRewriter: SyntaxRewriter {
+  override func visit(_ node: UnsafeExprSyntax) -> ExprSyntax {
+    return node.expression.with(\.leadingTrivia, node.leadingTrivia)
+  }
+}
+
+extension SyntaxProtocol {
+  /// Return a new syntax tree with all "unsafe" expressions removed.
+  var withoutUnsafeExpressions: Syntax {
+    RemoveUnsafeExprSyntaxRewriter().rewrite(self)
+  }
 }

test/Unsafe/module-interface.swift

@@ -0,0 +1,34 @@
+// RUN: %target-swift-emit-module-interface(%t.swiftinterface) %s -module-name UserModule -enable-experimental-feature AllowUnsafeAttribute  -enable-experimental-feature WarnUnsafe
+// RUN: %target-swift-typecheck-module-from-interface(%t.swiftinterface) -module-name UserModule
+// RUN: %FileCheck %s < %t.swiftinterface
+
+// REQUIRES: swift_feature_AllowUnsafeAttribute
+// REQUIRES: swift_feature_WarnUnsafe
+
+// CHECK: #if compiler(>=5.3) && $AllowUnsafeAttribute
+// CHECK: @unsafe public func getIntUnsafely() -> Swift.Int
+// CHECK: #else
+// CHECK: public func getIntUnsafely() -> Swift.Int
+// CHECK: #endif
+@unsafe public func getIntUnsafely() -> Int { 0 }
+
+// CHECK: @inlinable public func useUnsafeCode()
+@inlinable public func useUnsafeCode() {
+  // CHECK-NOT: unsafe
+  print( unsafe getIntUnsafely())
+}
+
+// CHECK: public protocol P
+public protocol P {
+  func f()
+}
+
+// CHECK: public struct X : @unsafe UserModule.P
+public struct X: @unsafe P {
+// CHECK:  #if compiler(>=5.3) && $AllowUnsafeAttribute
+// CHECK:  @unsafe public func f()
+// CHECK:  #else
+// CHECK:  public func f()
+// CHECK:  #endif
+  @unsafe public func f() { }
+}