From a176b0ce6d6be0cdd6c7b04c3d655cae567527e2 Mon Sep 17 00:00:00 2001
From: Rudi Grinberg <me@rgrinberg.com>
Date: Tue, 4 Aug 2020 00:56:34 -0700
Subject: [PATCH] Pass -g when compiling ppx preprocessor

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>
---
 CHANGES.md                | 2 ++
 src/dune/preprocessing.ml | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/CHANGES.md b/CHANGES.md
index 3bb8c04160..f195d7ca45 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -76,6 +76,8 @@ next
 - Fix a stack overflow when displaying large outputs (including diffs) (#3537,
   fixes #2767, #3490, @emillon)
 
+- Pass `-g` when compiling ppx preprocessors (#3671, @rgrinberg)
+
 2.6.0 (05/06/2020)
 ------------------
 
diff --git a/src/dune/preprocessing.ml b/src/dune/preprocessing.ml
index 87c765256c..53a391448b 100644
--- a/src/dune/preprocessing.ml
+++ b/src/dune/preprocessing.ml
@@ -332,7 +332,8 @@ let build_ppx_driver sctx ~dep_kind ~target ~pps ~pp_names =
         (Build.record_lib_deps
            (Lib_deps.info ~kind:dep_kind (Lib_deps.of_pps pp_names)))
     >>> Command.run compiler ~dir:(Path.build ctx.build_dir)
-          [ A "-o"
+          [ A "-g"
+          ; A "-o"
           ; Target target
           ; A "-w"
           ; A "-24"