From 788853b555b589c1283664171732c3c624a0e5b9 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <abdulras@fb.com>
Date: Wed, 26 Jun 2019 16:04:06 -0700
Subject: [PATCH] WIP/SwiftExpressionParser: preserve default argument thunks

---
 .../Swift/SwiftASTManipulator.cpp             | 38 +++++++++++++++++++
 .../Swift/SwiftASTManipulator.h               |  3 ++
 .../Swift/SwiftExpressionParser.cpp           | 14 +++++++
 3 files changed, 55 insertions(+)

diff --git a/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.cpp b/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.cpp
index c453af0a3b75..5bb4b06053ea 100644
--- a/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.cpp
+++ b/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.cpp
@@ -788,6 +788,44 @@ void SwiftASTManipulator::FindNonVariableDeclarations(
   }
 }
 
+void SwiftASTManipulator::EnumerateDefaultValuedArguments(llvm::SmallVectorImpl<std::pair<swift::FuncDecl *, std::vector<int>>> &FDAI) {
+  class DefaultArgumentThunkFinder : public swift::ASTWalker {
+    swift::SourceFile *SF;
+    llvm::SmallVectorImpl<std::pair<swift::FuncDecl *, std::vector<int>>> &FDAI;
+
+  public:
+    explicit DefaultArgumentThunkFinder(llvm::SmallVectorImpl<std::pair<swift::FuncDecl *, std::vector<int>>> &FDAI) : SF(nullptr), FDAI(FDAI) {}
+
+    void scan(swift::SourceFile &SF) {
+      this->SF = &SF;
+      for (swift::Decl *D : SF.Decls)
+        D->walk(*this);
+      this->SF = nullptr;
+    }
+
+  private:
+    bool walkToDeclPre(swift::Decl *D) override {
+      if (auto *FD = llvm::dyn_cast<swift::FuncDecl>(D)) {
+        if (swift::ParameterList *PL = FD->getParameters()) {
+          std::vector<int> DAI;
+          for (unsigned AI = 0, AE = PL->size(); AI < AE; ++AI) {
+            if (PL->get(AI)->getDefaultArgumentKind() ==
+                    swift::DefaultArgumentKind::None)
+              continue;
+            DAI.push_back(AI);
+          }
+          if (!DAI.empty())
+            FDAI.push_back(std::make_pair(FD, DAI));
+        }
+      }
+      return true;
+    }
+  };
+
+  DefaultArgumentThunkFinder DATF(FDAI);
+  DATF.scan(m_source_file);
+}
+
 void SwiftASTManipulator::InsertResult(
     swift::VarDecl *result_var, swift::Type &result_type,
     SwiftASTManipulator::ResultLocationInfo &result_info) {
diff --git a/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.h b/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.h
index 4213550fb221..fd30f1c0fd3e 100644
--- a/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.h
+++ b/source/Plugins/ExpressionParser/Swift/SwiftASTManipulator.h
@@ -164,6 +164,9 @@ class SwiftASTManipulator : public SwiftASTManipulatorBase {
   void FindNonVariableDeclarations(
       llvm::SmallVectorImpl<swift::ValueDecl *> &non_variables);
 
+  void EnumerateDefaultValuedArguments(
+    llvm::SmallVectorImpl<std::pair<swift::FuncDecl *, std::vector<int>>> &DefaultValuedArgumentIndices);
+
   bool FixCaptures();
 
   swift::ValueDecl *MakeGlobalTypealias(swift::Identifier name,
diff --git a/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp b/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp
index 09db606ef243..9cce4391bbb8 100644
--- a/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp
+++ b/source/Plugins/ExpressionParser/Swift/SwiftExpressionParser.cpp
@@ -68,6 +68,7 @@
 #include "swift/Frontend/Frontend.h"
 #include "swift/Parse/LocalContext.h"
 #include "swift/Parse/PersistentParserState.h"
+#include "swift/SIL/SILDeclRef.h"
 #include "swift/SIL/SILDebuggerClient.h"
 #include "swift/SIL/SILFunction.h"
 #include "swift/SIL/SILModule.h"
@@ -1661,9 +1662,22 @@ unsigned SwiftExpressionParser::Parse(DiagnosticManager &diagnostic_manager,
         variable_map[name] = *var_info;
       }
 
+  llvm::SmallVector<std::pair<swift::FuncDecl *, std::vector<int>>, 4> FDAIs;
+  parsed_expr->code_manipulator->EnumerateDefaultValuedArguments(FDAIs);
+
   std::unique_ptr<swift::SILModule> sil_module(swift::performSILGeneration(
       parsed_expr->source_file, swift_ast_ctx->GetSILOptions()));
 
+  for (const auto &FDAI : FDAIs) {
+    swift::FuncDecl *FD = FDAI.first;
+    std::vector<int> DAI = FDAI.second;
+    for (int AI : DAI) {
+      auto DAG = swift::SILDeclRef::getDefaultArgGenerator(FD, AI);
+      swift::SILFunction *F = sil_module->lookUpFunction(DAG);
+      F->dump();
+    }
+  }
+
   if (log) {
     std::string s;
     llvm::raw_string_ostream ss(s);