From 884d59178735bcb5d5db7db97a05ad62a175493b Mon Sep 17 00:00:00 2001
From: Ben Burdette <bburdette@protonmail.com>
Date: Fri, 20 May 2022 10:33:50 -0600
Subject: [PATCH] debugRepl ftn pointer

---
 src/libcmd/command.cc  | 27 +++++++++++++++++++++++++++
 src/libexpr/eval.cc    | 12 ++++++++----
 src/libexpr/eval.hh    | 10 +++++-----
 src/libexpr/primops.cc |  2 +-
 4 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index a4ea5bc33..b61b9b61d 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -120,7 +120,34 @@ ref<EvalState> EvalCommand::getEvalState()
             ;
 
         evalState->debugMode = startReplOnEvalErrors; 
+
         // TODO move this somewhere else.  Its only here to get the evalState ptr!
+        if (startReplOnEvalErrors) {
+            evalState->debugRepl = &runRepl;        
+        };
+            // // debuggerHook = [evalState{ref<EvalState>(evalState)}](const Error * error, const Env & env, const Expr & expr) {
+            // debuggerHook = [](EvalState & evalState, const Error * error, const Env & env, const Expr & expr) {
+            //     auto dts =
+            //         error && expr.getPos()
+            //         ? std::make_unique<DebugTraceStacker>(
+            //             evalState,
+            //             DebugTrace {
+            //                 .pos = error->info().errPos ? *error->info().errPos : evalState.positions[expr.getPos()],
+            //                 .expr = expr,
+            //                 .env = env,
+            //                 .hint = error->info().msg,
+            //                 .isError = true
+            //             })
+            //         : nullptr;
+
+            //     if (error)
+            //         printError("%s\n\n" ANSI_BOLD "Starting REPL to allow you to inspect the current state of the evaluator.\n" ANSI_NORMAL, error->what());
+
+            //     auto se = evalState.getStaticEnv(expr);
+            //     if (se) {
+            //         auto vm = mapStaticEnvBindings(evalState.symbols, *se.get(), env);
+            //         runRepl(evalState, *vm);
+            //     }
         // if (startReplOnEvalErrors)
           
         //     // debuggerHook = [evalState{ref<EvalState>(evalState)}](const Error * error, const Env & env, const Expr & expr) {
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 1cde4a9ab..5faecdbe3 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -463,7 +463,7 @@ EvalState::EvalState(
     , emptyBindings(0)
     , store(store)
     , buildStore(buildStore ? buildStore : store)
-    , debugMode(false)
+    , debugRepl(0)
     , debugStop(false)
     , debugQuit(false)
     , regexCache(makeRegexCache())
@@ -811,8 +811,12 @@ std::unique_ptr<ValMap> mapStaticEnvBindings(const SymbolTable & st, const Stati
     return vm;
 }
 
-void EvalState::debugRepl(const Error * error, const Env & env, const Expr & expr)
+void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr & expr)
 {
+    // double check we've got the debugRepl ftn pointer.
+    if (!debugRepl)
+        return;
+  
     auto dts =
         error && expr.getPos()
         ? std::make_unique<DebugTraceStacker>(
@@ -832,7 +836,7 @@ void EvalState::debugRepl(const Error * error, const Env & env, const Expr & exp
     auto se = getStaticEnv(expr);
     if (se) {
         auto vm = mapStaticEnvBindings(symbols, *se.get(), env);
-        runRepl(*this, *vm);
+        (debugRepl)(*this, *vm);
     }
 }
 
@@ -1070,7 +1074,7 @@ DebugTraceStacker::DebugTraceStacker(EvalState & evalState, DebugTrace t)
 {
     evalState.debugTraces.push_front(trace);
     if (evalState.debugStop && evalState.debugMode)
-        evalState.debugRepl(nullptr, trace.env, trace.expr);
+        evalState.runDebugRepl(nullptr, trace.env, trace.expr);
 }
 
 void Value::mkString(std::string_view s)
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 711a4d6be..90bd5497b 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -48,8 +48,6 @@ struct Env
     Value * values[0];
 };
 
-extern void runRepl(ref<EvalState> evalState, const ValMap & extraEnv);
-
 void printEnvBindings(const EvalState &es, const Expr & expr, const Env & env);
 void printEnvBindings(const SymbolTable & st, const StaticEnv & se, const Env & env, int lvl = 0);
 
@@ -129,6 +127,8 @@ public:
     RootValue vImportedDrvToDerivation = nullptr;
 
     /* Debugger */
+    void (* debugRepl)(EvalState & es, const ValMap & extraEnv);
+
     bool debugMode;
     bool debugStop;
     bool debugQuit;
@@ -143,14 +143,14 @@ public:
             return std::shared_ptr<const StaticEnv>();;
     }
 
-    void debugRepl(const Error * error, const Env & env, const Expr & expr);
+    void runDebugRepl(const Error * error, const Env & env, const Expr & expr);
 
     template<class E>
     [[gnu::noinline, gnu::noreturn]]
     void debugThrow(const E &error, const Env & env, const Expr & expr)
     {
         if (debugMode)
-            debugRepl(&error, env, expr);
+            runDebugRepl(&error, env, expr);
 
         throw error;
     }
@@ -164,7 +164,7 @@ public:
         // DebugTrace stack.
         if (debugMode && !debugTraces.empty()) {
             const DebugTrace & last = debugTraces.front();
-            debugRepl(&e, last.env, last.expr);
+            runDebugRepl(&e, last.env, last.expr);
         }
 
         throw e;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index f7429197a..3ca377b7c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -765,7 +765,7 @@ static RegisterPrimOp primop_break({
             });
 
             auto & dt = state.debugTraces.front();
-            state.debugRepl(&error, dt.env, dt.expr);
+            state.runDebugRepl(&error, dt.env, dt.expr);
 
             if (state.debugQuit) {
                 // If the user elects to quit the repl, throw an exception.