Add flag for dumping ClangImporter lookup tables

ClangImporter’s SwiftLookupTables map Swift names to their corresponding Clang declarations. These tables are built into a module’s clang .pcm file and missing or inaccurate entries can cause name lookup to fail to find an imported declaration.

Swift has always included a helper function that would dump these tables, and swift-ide-test has a command-line switch that would invoke it, but these tools are clumsy to use in many debugging scenarios. Add a frontend flag that dumps the tables at the end of the frontend job, making it a lot easier to get at this information in the context of a specific compilation.

Author: beccadax

include/swift/AST/ClangModuleLoader.h

@@ -144,6 +144,7 @@ class ClangModuleLoader : public ModuleLoader {
   virtual clang::Sema &getClangSema() const = 0;
   virtual const clang::CompilerInstance &getClangInstance() const = 0;
   virtual void printStatistics() const = 0;
+  virtual void dumpSwiftLookupTables() const = 0;
 
   /// Returns the module that contains imports and declarations from all loaded
   /// Objective-C header files.

include/swift/ClangImporter/ClangImporter.h

@@ -538,7 +538,7 @@ class ClangImporter final : public ClangModuleLoader {
   void printStatistics() const override;
 
   /// Dump Swift lookup tables.
-  void dumpSwiftLookupTables();
+  void dumpSwiftLookupTables() const override;
 
   /// Given the path of a Clang module, collect the names of all its submodules.
   /// Calling this function does not load the module.

include/swift/Frontend/FrontendOptions.h

@@ -280,6 +280,10 @@ class FrontendOptions {
   /// termination.
   bool PrintClangStats = false;
 
+  /// Indicates whether or not the Clang importer should dump lookup tables
+  /// upon termination.
+  bool DumpClangLookupTables = false;
+
   /// Indicates whether standard help should be shown.
   bool PrintHelp = false;
 

include/swift/Option/FrontendOptions.td

@@ -580,6 +580,10 @@ def stack_promotion_limit : Separate<["-"], "stack-promotion-limit">,
 def dump_clang_diagnostics : Flag<["-"], "dump-clang-diagnostics">,
   HelpText<"Dump Clang diagnostics to stderr">;
 
+def dump_clang_lookup_tables : Flag<["-"], "dump-clang-lookup-tables">,
+  HelpText<"Dump the importer's Swift-name-to-Clang-name lookup tables to "
+           "stderr">;
+
 def disable_modules_validate_system_headers : Flag<["-"], "disable-modules-validate-system-headers">,
   HelpText<"Disable validating system headers in the Clang importer">;
 

lib/ClangImporter/ClangImporter.cpp

@@ -6269,7 +6269,7 @@ EffectiveClangContext ClangImporter::Implementation::getEffectiveClangContext(
   return EffectiveClangContext();
 }
 
-void ClangImporter::dumpSwiftLookupTables() {
+void ClangImporter::dumpSwiftLookupTables() const {
   Impl.dumpSwiftLookupTables();
 }
 

lib/Frontend/ArgsToFrontendOptionsConverter.cpp

@@ -170,6 +170,8 @@ bool ArgsToFrontendOptionsConverter::convert(
   computeDebugTimeOptions();
   computeTBDOptions();
 
+  Opts.DumpClangLookupTables |= Args.hasArg(OPT_dump_clang_lookup_tables);
+
   Opts.CheckOnoneSupportCompleteness = Args.hasArg(OPT_check_onone_completeness);
 
   Opts.ParseStdlib |= Args.hasArg(OPT_parse_stdlib);

lib/FrontendTool/FrontendTool.cpp

@@ -1117,6 +1117,9 @@ static void performEndOfPipelineActions(CompilerInstance &Instance) {
   if (auto *stats = ctx.Stats)
     countASTStats(*stats, Instance);
 
+  if (opts.DumpClangLookupTables && ctx.getClangModuleLoader())
+    ctx.getClangModuleLoader()->dumpSwiftLookupTables();
+
   // Report mangling stats if there was no error.
   if (!ctx.hadError())
     Mangle::printManglingStats();

test/IDE/dump_swift_lookup_tables.swift

@@ -1,5 +1,9 @@
-// RUN: %target-swift-ide-test -dump-importer-lookup-table -source-filename %s -import-objc-header %S/Inputs/swift_name.h -I %S/Inputs/custom-modules > %t.log 2>&1
-// RUN: %FileCheck %s < %t.log
+// RUN: %target-swift-ide-test -dump-importer-lookup-table -source-filename %s -import-objc-header %S/Inputs/swift_name.h -I %S/Inputs/custom-modules > %t.ide-test.log 2>&1
+// RUN: %FileCheck %s < %t.ide-test.log
+
+// RUN: %target-typecheck-verify-swift -dump-clang-lookup-tables -import-objc-header %S/Inputs/swift_name.h -I %S/Inputs/custom-modules > %t.frontend.log 2>&1
+// RUN: %FileCheck %s < %t.frontend.log
+// RUN: false
 
 // REQUIRES: objc_interop
 import ImportAsMember

test/IDE/dump_swift_lookup_tables_objc.swift

@@ -1,5 +1,8 @@
-// RUN: %target-swift-ide-test -dump-importer-lookup-table -source-filename %s -import-objc-header %S/Inputs/swift_name_objc.h > %t.log 2>&1
-// RUN: %FileCheck %s < %t.log
+// RUN: %target-swift-ide-test -dump-importer-lookup-table -source-filename %s -import-objc-header %S/Inputs/swift_name_objc.h > %t.ide-test.log 2>&1
+// RUN: %FileCheck %s < %t.ide-test.log
+
+// RUN: %target-typecheck-verify-swift -dump-clang-lookup-tables -import-objc-header %S/Inputs/swift_name_objc.h > %t.frontend.log 2>&1
+// RUN: %FileCheck %s < %t.frontend.log
 
 // REQUIRES: objc_interop
 // REQUIRES: OS=macosx