From c8d3b8404ec9cf82f23f115202e68c1bcb82a23c Mon Sep 17 00:00:00 2001
From: James Lamb <jaylamb20@gmail.com>
Date: Mon, 10 May 2021 17:15:29 -0500
Subject: [PATCH 1/2] [R-package] suppress Wcast-function-type warning in
 CMake-based gcc and MinGW builds (fixes #4273)

---
 R-package/src/lightgbm_R.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/R-package/src/lightgbm_R.cpp b/R-package/src/lightgbm_R.cpp
index cedf53545bd9..063ddc27ba6f 100644
--- a/R-package/src/lightgbm_R.cpp
+++ b/R-package/src/lightgbm_R.cpp
@@ -680,6 +680,8 @@ SEXP LGBM_BoosterDumpModel_R(LGBM_SE handle,
   R_API_END();
 }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wcast-function-type"
 // .Call() calls
 static const R_CallMethodDef CallEntries[] = {
   {"LGBM_GetLastError_R"              , (DL_FUNC) &LGBM_GetLastError_R              , 0},
@@ -725,6 +727,7 @@ static const R_CallMethodDef CallEntries[] = {
   {"LGBM_BoosterDumpModel_R"          , (DL_FUNC) &LGBM_BoosterDumpModel_R          , 3},
   {NULL, NULL, 0}
 };
+#pragma GCC diagnostic pop
 
 LIGHTGBM_C_EXPORT void R_init_lightgbm(DllInfo *dll);
 

From 6c6016dacacef12b7f29c7b1b1fc93ed4648fcab Mon Sep 17 00:00:00 2001
From: James Lamb <jaylamb20@gmail.com>
Date: Mon, 10 May 2021 19:03:08 -0500
Subject: [PATCH 2/2] suppress warning from CMake side

---
 CMakeLists.txt               | 3 +++
 R-package/src/lightgbm_R.cpp | 3 ---
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 41fb21f5e54c..48c1ac040f26 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -283,6 +283,9 @@ if(UNIX OR MINGW OR CYGWIN)
     if(NOT USE_OPENMP)
         SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unknown-pragmas -Wno-unused-private-field")
     endif()
+    if(__BUILD_FOR_R AND CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+        SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-cast-function-type")
+    endif()
 endif()
 
 if(WIN32 AND MINGW)
diff --git a/R-package/src/lightgbm_R.cpp b/R-package/src/lightgbm_R.cpp
index 063ddc27ba6f..cedf53545bd9 100644
--- a/R-package/src/lightgbm_R.cpp
+++ b/R-package/src/lightgbm_R.cpp
@@ -680,8 +680,6 @@ SEXP LGBM_BoosterDumpModel_R(LGBM_SE handle,
   R_API_END();
 }
 
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wcast-function-type"
 // .Call() calls
 static const R_CallMethodDef CallEntries[] = {
   {"LGBM_GetLastError_R"              , (DL_FUNC) &LGBM_GetLastError_R              , 0},
@@ -727,7 +725,6 @@ static const R_CallMethodDef CallEntries[] = {
   {"LGBM_BoosterDumpModel_R"          , (DL_FUNC) &LGBM_BoosterDumpModel_R          , 3},
   {NULL, NULL, 0}
 };
-#pragma GCC diagnostic pop
 
 LIGHTGBM_C_EXPORT void R_init_lightgbm(DllInfo *dll);