From 39938dacb3bf66d3ec460337dc2700a21b8271a3 Mon Sep 17 00:00:00 2001
From: Weijia Wang <9713184+wegank@users.noreply.github.com>
Date: Mon, 19 Dec 2022 05:28:41 +0100
Subject: [PATCH] grpc: expose cxxStandard

---
 pkgs/development/libraries/grpc/default.nix | 45 +++++++++++----------
 pkgs/top-level/all-packages.nix             |  2 +-
 2 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/pkgs/development/libraries/grpc/default.nix b/pkgs/development/libraries/grpc/default.nix
index b924f3f51d34..8a3a936b1453 100644
--- a/pkgs/development/libraries/grpc/default.nix
+++ b/pkgs/development/libraries/grpc/default.nix
@@ -54,28 +54,18 @@ stdenv.mkDerivation rec {
   buildInputs = [ openssl protobuf ]
     ++ lib.optionals stdenv.isLinux [ libnsl ];
 
-  cmakeFlags =
-    let
-      # Needs to be compiled with -std=c++11 for clang < 11. Interestingly this is
-      # only an issue with the useLLVM stdenv, not the darwin stdenv…
-      # https://github.com/grpc/grpc/issues/26473#issuecomment-860885484
-      useLLVMAndOldCC = (stdenv.hostPlatform.useLLVM or false) && lib.versionOlder stdenv.cc.cc.version "11.0";
-      # With GCC 9 (current aarch64-linux) it fails with c++17 but OK with c++14.
-      useOldGCC = !(stdenv.hostPlatform.useLLVM or false) && lib.versionOlder stdenv.cc.cc.version "10";
-      cxxStandard = if useLLVMAndOldCC then "11" else if useOldGCC then "14" else "17";
-    in
-    [
-      "-DgRPC_ZLIB_PROVIDER=package"
-      "-DgRPC_CARES_PROVIDER=package"
-      "-DgRPC_RE2_PROVIDER=package"
-      "-DgRPC_SSL_PROVIDER=package"
-      "-DgRPC_PROTOBUF_PROVIDER=package"
-      "-DgRPC_ABSL_PROVIDER=package"
-      "-DBUILD_SHARED_LIBS=ON"
-      "-DCMAKE_CXX_STANDARD=${cxxStandard}"
-    ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
-      "-D_gRPC_PROTOBUF_PROTOC_EXECUTABLE=${buildPackages.protobuf}/bin/protoc"
-    ];
+  cmakeFlags = [
+    "-DgRPC_ZLIB_PROVIDER=package"
+    "-DgRPC_CARES_PROVIDER=package"
+    "-DgRPC_RE2_PROVIDER=package"
+    "-DgRPC_SSL_PROVIDER=package"
+    "-DgRPC_PROTOBUF_PROVIDER=package"
+    "-DgRPC_ABSL_PROVIDER=package"
+    "-DBUILD_SHARED_LIBS=ON"
+    "-DCMAKE_CXX_STANDARD=${passthru.cxxStandard}"
+  ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
+    "-D_gRPC_PROTOBUF_PROTOC_EXECUTABLE=${buildPackages.protobuf}/bin/protoc"
+  ];
 
   # CMake creates a build directory by default, this conflicts with the
   # basel BUILD file on case-insensitive filesystems.
@@ -97,6 +87,17 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilds = true;
 
+  passthru.cxxStandard =
+    let
+      # Needs to be compiled with -std=c++11 for clang < 11. Interestingly this is
+      # only an issue with the useLLVM stdenv, not the darwin stdenv…
+      # https://github.com/grpc/grpc/issues/26473#issuecomment-860885484
+      useLLVMAndOldCC = (stdenv.hostPlatform.useLLVM or false) && lib.versionOlder stdenv.cc.cc.version "11.0";
+      # With GCC 9 (current aarch64-linux) it fails with c++17 but OK with c++14.
+      useOldGCC = !(stdenv.hostPlatform.useLLVM or false) && lib.versionOlder stdenv.cc.cc.version "10";
+    in
+    (if useLLVMAndOldCC then "11" else if useOldGCC then "14" else "17");
+
   passthru.tests = {
     inherit (python3.pkgs) grpcio-status grpcio-tools;
     inherit arrow-cpp;
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 4b906f8c5f42..23fde6594371 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -19522,7 +19522,7 @@ with pkgs;
   grpc = callPackage ../development/libraries/grpc {
     # grpc builds with c++17 so abseil must also be built that way
     abseil-cpp = abseil-cpp_202206.override {
-      cxxStandard = "17";
+      cxxStandard = grpc.cxxStandard;
     };
   };