Merge pull request #13512 from xokdvium/speed-up-builds-pch

Reintroduce precompiled headers

src/libcmd/meson.build

@@ -92,6 +92,7 @@ this_library = library(
   link_args: linker_export_flags,
   prelink : true, # For C++ static initializers
   install : true,
+  cpp_pch : ['pch/precompiled-headers.hh']
 )
 
 install_headers(headers, subdir : 'nix/cmd', preserve_path : true)

src/libcmd/pch/precompiled-headers.hh

@@ -0,0 +1,4 @@
+#include "nix/cmd/installables.hh"
+#include "nix/expr/eval.hh"
+#include "nix/util/util.hh"
+#include "nix/flake/flake.hh"

src/libexpr/meson.build

@@ -178,6 +178,7 @@ this_library = library(
   link_args: linker_export_flags,
   prelink : true, # For C++ static initializers
   install : true,
+  cpp_pch : ['pch/precompiled-headers.hh']
 )
 
 install_headers(headers, subdir : 'nix/expr', preserve_path : true)

src/libexpr/pch/precompiled-headers.hh

@@ -0,0 +1 @@
+#include "nix/expr/eval.hh"

src/libstore/meson.build

@@ -348,6 +348,7 @@ this_library = library(
   link_args: linker_export_flags,
   prelink : true, # For C++ static initializers
   install : true,
+  cpp_pch : ['pch/precompiled-headers.hh']
 )
 
 install_headers(headers, subdir : 'nix/store', preserve_path : true)

src/libstore/pch/precompiled-headers.hh

@@ -0,0 +1,8 @@
+#include "nix/store/store-api.hh"
+#include "nix/store/realisation.hh"
+#include "nix/store/derived-path.hh"
+#include "nix/store/derivations.hh"
+#include "nix/store/local-store.hh"
+#include "nix/util/util.hh"
+
+#include <nlohmann/json.hpp>

src/libutil/meson.build

@@ -191,6 +191,7 @@ this_library = library(
   link_args: linker_export_flags,
   prelink : true, # For C++ static initializers
   install : true,
+  cpp_pch : 'pch/precompiled-headers.hh'
 )
 
 install_headers(headers, subdir : 'nix/util', preserve_path : true)

src/libutil/pch/precompiled-headers.hh

@@ -0,0 +1,7 @@
+#include "nix/util/util.hh"
+#include "nix/util/file-system.hh"
+#include "nix/util/serialise.hh"
+#include "nix/util/signals.hh"
+#include "nix/util/source-accessor.hh"
+
+#include <nlohmann/json.hpp>

src/nix/meson.build

@@ -186,6 +186,7 @@ this_exe = executable(
   include_directories : include_dirs,
   link_args: linker_export_flags,
   install : true,
+  cpp_pch : ['pch/precompiled-headers.hh']
 )
 
 meson.override_find_program('nix', this_exe)

src/nix/pch/precompiled-headers.hh

@@ -0,0 +1,3 @@
+#include "nix/cmd/command.hh"
+#include "nix/expr/eval.hh"
+#include "nix/main/shared.hh"