Address code review comments and build failure

Author: DougGregor

include/swift/AST/IfConfigClauseRangeInfo.h

@@ -1,4 +1,4 @@
-//===--- ASTBridging.h - header for the swift SILBridging module ----------===//
+//===--- IfConfigClauseRangeInfo.h - header for #if clauses -=====---------===//
 //
 // This source file is part of the Swift.org open source project
 //

lib/AST/ASTBridging.cpp

@@ -238,7 +238,7 @@ bool BridgedASTContext_canImport(BridgedASTContext cContext,
 
   // FIXME: The source location here is empty because build configurations
   // are supposed to be completely separated from source code. We could re-plumb
-  // things to have any errors reported up thruough the "canImportModule"
+  // things to have any errors reported up through the "canImportModule"
   // API.
   ImportPath::Module::Builder builder(
       cContext.unbridged(), importPath.unbridged(), /*separator=*/'.',

lib/AST/Module.cpp

@@ -2950,8 +2950,12 @@ IfConfigClauseRangeInfo::getWholeRange(const SourceManager &SM) const {
 
 void SourceFile::recordIfConfigClauseRangeInfo(
     const IfConfigClauseRangeInfo &range) {
+#if SWIFT_BUILD_SWIFT_SYNTAX
+  // Don't record ranges; they'll be extracted from swift-syntax when needed.
+#else
   IfConfigClauseRanges.Ranges.push_back(range);
   IfConfigClauseRanges.IsSorted = false;
+#endif
 }
 
 ArrayRef<IfConfigClauseRangeInfo> SourceFile::getIfConfigClauseRanges() const {

lib/ASTGen/Sources/ASTGen/CompilerBuildConfiguration.swift

@@ -1,4 +1,4 @@
-//===--- CompilerBuildConfiguration.swift --------------\------------------===//
+//===--- CompilerBuildConfiguration.swift ---------------------------------===//
 //
 // This source file is part of the Swift.org open source project
 //

lib/CompilerSwiftSyntax/CMakeLists.txt

@@ -30,6 +30,7 @@ includeSwiftSyntax()
 
 set(compiler_swiftsyntax_libs
   _CompilerSwiftSyntax
+  _CompilerSwiftIfConfig
   _CompilerSwiftOperators
   _CompilerSwiftSyntaxBuilder
   _CompilerSwiftParser