meson: migrate generated headers to a generator() object

Change-Id: Ie7b9cab4189825e8f02dfb39d298302bc36fcb61

meson.build

@@ -116,6 +116,18 @@ deps += lowdown
 bash = find_program('bash')
 lsof = find_program('lsof')
 
+# This is how Nix does generated headers...
+# FIXME(Qyriad): do we really need to use the shell for this?
+gen_header = generator(
+  bash,
+  arguments : [
+    '-c',
+    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
+  ],
+  capture : true,
+  output : '@PLAINNAME@.gen.hh',
+)
+
 #
 # Configuration
 #

src/libstore/meson.build

@@ -1,24 +1,5 @@
-schema_sql_gen = custom_target(
-  input : 'schema.sql',
-  output : 'schema.sql.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
-
-ca_specific_schema = custom_target(
-  input : 'ca-specific-schema.sql',
-  output : 'ca-specific-schema.sql.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
+schema_sql_gen = gen_header.process('schema.sql')
+ca_specific_schema_gen = gen_header.process('ca-specific-schema.sql')
 
 libstore_sources = files(
   'binary-cache-store.cc',
@@ -117,7 +98,7 @@ endforeach
 libstore = library(
   'nixstore',
   schema_sql_gen,
-  ca_specific_schema,
+  ca_specific_schema_gen,
   libstore_sources,
   dependencies : [
     libarchive,

src/meson.build

@@ -25,43 +25,27 @@ nix_build_sources = files(
 nix_channel_sources = files(
   'nix-channel/nix-channel.cc',
 )
-unpack_channel_gen = custom_target(
-  input : 'nix-channel/unpack-channel.nix',
-  output : 'unpack-channel.nix.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
+unpack_channel_gen = gen_header.process('nix-channel/unpack-channel.nix')
 nix_collect_garbage_sources = files(
   'nix-collect-garbage/nix-collect-garbage.cc',
 )
 nix_copy_closure_sources = files(
   'nix-copy-closure/nix-copy-closure.cc',
 )
+nix_env_buildenv_gen = gen_header.process('nix-env/buildenv.nix')
+nix_env_sources = files(
+  'nix-env/nix-env.cc',
+  'nix-env/user-env.cc',
+)
+nix_instantiate_sources = files(
+  'nix-instantiate/nix-instantiate.cc',
+)
 nix_store_sources = files(
   'nix-store/dotgraph.cc',
   'nix-store/graphml.cc',
   'nix-store/nix-store.cc',
 )
 
-nix_env_buildenv = custom_target(
-  input : 'nix-env/buildenv.nix',
-  output : 'buildenv.nix.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
-nix_env_sources = files(
-  'nix-env/nix-env.cc',
-  'nix-env/user-env.cc',
-)
-
 # Hurray for Meson list flattening!
 nix2_commands_sources = [
   build_remote_sources,
@@ -70,9 +54,10 @@ nix2_commands_sources = [
   unpack_channel_gen,
   nix_collect_garbage_sources,
   nix_copy_closure_sources,
-  nix_store_sources,
-  nix_env_buildenv,
+  nix_env_buildenv_gen,
   nix_env_sources,
+  nix_instantiate_sources,
+  nix_store_sources,
 ]
 
 # Finally, the nix command itself, which all of the other commands are implmented in terms of

src/nix/meson.build

@@ -1,24 +1,6 @@
-generate_manpage_gen = custom_target(
-  input : meson.project_source_root() / 'doc/manual/generate-manpage.nix',
-  output : 'generate-manpage.nix.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
+generate_manpage_gen = gen_header.process(meson.project_source_root() / 'doc/manual/generate-manpage.nix')
 
-utils_gen = custom_target(
-  input : meson.project_source_root() / 'doc/manual/utils.nix',
-  output : 'utils.nix.gen.hh',
-  command : [
-    bash,
-    '-c',
-    'echo \'R"foo(\' | cat - @INPUT@ && echo \')foo"\'',
-  ],
-  capture : true,
-)
+utils_gen = gen_header.process(meson.project_source_root() / 'doc/manual/utils.nix')
 
 nix_sources = files(
   'add-to-store.cc',