Use ccache in the default devShell

.devcontainer/Dockerfile

@@ -1 +1,4 @@
 FROM ghcr.io/xtruder/nix-devcontainer:v1
+RUN echo 'extra-sandbox-paths = /nix/var/cache/ccache' | sudo tee -a /etc/nix/nix.conf
+RUN sudo mkdir -m0770 -p /nix/var/cache/ccache
+RUN sudo chown --reference=/nix/store /nix/var/cache/ccache

.github/workflows/nix.yml

@@ -46,7 +46,12 @@ jobs:
           extra-substituters = s3://hhvm-nix-cache?region=us-west-2&endpoint=hhvm-nix-cache.s3-accelerate.amazonaws.com
           extra-trusted-substituters = s3://hhvm-nix-cache?region=us-west-2&endpoint=hhvm-nix-cache.s3-accelerate.amazonaws.com
           extra-trusted-public-keys = hhvm-nix-cache-1:MvKxscw16fAq6835oG8sbRgTGITb+1xGfYNhs+ee4yo=
+          extra-sandbox-paths = /nix/var/cache/ccache
           sandbox = false
+    - run: |
+        # See https://nixos.wiki/wiki/CCache
+        sudo mkdir -m0770 -p /nix/var/cache/ccache
+        sudo chown --reference=/nix/store /nix/var/cache/ccache
     - run: nix build --print-build-logs "git+file://$(pwd)?submodules=1&shallow=1#${{matrix.package}}"
     - run: nix profile install --print-build-logs "git+file://$(pwd)?submodules=1&shallow=1#${{matrix.package}}"
     - run: hhvm --version

clang.code-workspace

@@ -23,10 +23,6 @@
         ]
       }
     },
-    "cmake.configureArgs": [
-      "-C",
-      "${env:CMAKE_INIT_CACHE}"
-    ],
     "cmake.buildDirectory": "${workspaceFolder}/_build"
   },
   "extensions": {

flake.nix

@@ -39,20 +39,34 @@
                 ];
                 inherit (hhvm)
                   NIX_CFLAGS_COMPILE
-                  CMAKE_INIT_CACHE;
+                  CMAKE_TOOLCHAIN_FILE;
+                ${if hhvm?RUSTC_WRAPPER then "RUSTC_WRAPPER" else null} =
+                  hhvm.RUSTC_WRAPPER;
               };
         in
         rec {
           packages.hhvm = pkgs.callPackage ./hhvm.nix {
             lastModifiedDate = self.lastModifiedDate;
+            isDefaultStdlib = true;
           };
+          packages.hhvm_ccache = packages.hhvm.overrideAttrs (finalAttrs: previousAttrs: {
+            RUSTC_WRAPPER = "${pkgs.sccache}/bin/sccache";
+            CMAKE_TOOLCHAIN_FILE = pkgs.writeTextFile {
+              name = "toolchain.cmake";
+              text = ''
+                ${builtins.readFile packages.hhvm.CMAKE_TOOLCHAIN_FILE}
+                set(CMAKE_C_COMPILER_LAUNCHER "${pkgs.sccache}/bin/sccache" CACHE STRING "C compiler launcher" FORCE)
+                set(CMAKE_CXX_COMPILER_LAUNCHER "${pkgs.sccache}/bin/sccache" CACHE STRING "C++ compiler launcher" FORCE)
+              '';
+            };
+          });
           packages.hhvm_clang = packages.hhvm.override {
             stdenv = pkgs.llvmPackages_14.stdenv;
           };
           packages.default = packages.hhvm;
 
           devShells.clang = devShellForPackage packages.hhvm_clang;
-          devShells.default = devShellForPackage packages.hhvm;
+          devShells.default = devShellForPackage packages.hhvm_ccache;
 
           ${if pkgs.hostPlatform.isLinux then "bundlers" else null} =
             let

hhvm.code-workspace

@@ -17,10 +17,6 @@
         "path": "nix-shell"
       }
     },
-    "cmake.configureArgs": [
-      "-C",
-      "${env:CMAKE_INIT_CACHE}"
-    ],
     "cmake.buildDirectory": "${workspaceFolder}/_build"
   },
   "extensions": {

hhvm.nix

@@ -25,6 +25,9 @@
 , gperftools
 , hostPlatform
 , icu
+# TODO(https://github.com/NixOS/nixpkgs/pull/193086): Use stdenv.cc.libcxx to
+# detect C++ runtime once it is available
+, isDefaultStdlib
 , imagemagick6
 , jemalloc
 , lastModifiedDate
@@ -70,9 +73,6 @@
 , zstd
 }:
 let
-  # TODO(https://github.com/NixOS/nixpkgs/pull/193086): Use stdenv.cc.libcxx once it is available
-  isDefaultStdlib =
-    builtins.match ".*-stdlib=\+\+.*" (builtins.readFile "${stdenv.cc}/nix-support/libcxx-ldflags") == null;
   versionParts =
     builtins.match
       ''
@@ -214,8 +214,8 @@ stdenv.mkDerivation rec {
       "-Wno-error=unused-command-line-argument"
     ];
 
-  CMAKE_INIT_CACHE = writeTextFile {
-    name = "init-cache.cmake";
+  CMAKE_TOOLCHAIN_FILE = writeTextFile {
+    name = "toolchain.cmake";
     text = ''
       set(ENABLE_SYSTEM_LOCALE_ARCHIVE ON CACHE BOOL "Use system locale archive as the default LOCALE_ARCHIVE for nix patched glibc" FORCE)
       set(CAN_USE_SYSTEM_ZSTD ON CACHE BOOL "Use system zstd" FORCE)
@@ -232,8 +232,6 @@ stdenv.mkDerivation rec {
     '';
   };
 
-  cmakeFlags = [ "-C" CMAKE_INIT_CACHE ];
-
   prePatch = ''
     patchShebangs .
   '';