From b1e94a02fe7be2001186668227d1837642ee4fce Mon Sep 17 00:00:00 2001
From: Andrew Kaster <akaster@serenityos.org>
Date: Fri, 5 May 2023 12:35:44 -0600
Subject: [PATCH] Meta: Add compiled_action from LLVM, use it to generate TZDB
 sources

---
 Meta/gn/build/compiled_action.gni             | 77 +++++++++++++++++++
 Meta/gn/build/run_compiled_binary.py          |  8 ++
 .../Userland/Libraries/LibTimeZone/BUILD.gn   | 29 ++++++-
 3 files changed, 112 insertions(+), 2 deletions(-)
 create mode 100644 Meta/gn/build/compiled_action.gni
 create mode 100644 Meta/gn/build/run_compiled_binary.py

diff --git a/Meta/gn/build/compiled_action.gni b/Meta/gn/build/compiled_action.gni
new file mode 100644
index 0000000000..513a41d2c7
--- /dev/null
+++ b/Meta/gn/build/compiled_action.gni
@@ -0,0 +1,77 @@
+# Defines compiled_action().
+#
+# compiled_action() is like action(), except that it runs a built binary
+# instead of a script.
+#
+# Parameters:
+#
+#   tool (required)
+#       [label] Label of the tool to run. This should be an executable, and
+#       this label should not include a toolchain (anything in parens). This
+#       tool will be built for the host.
+#
+#   outputs (required)
+#       [list of files] Same meaning as for action().
+#
+#   args (required)
+#       [list of strings] Flags to pass to the built binary. Almost identical
+#       to action()'s `args`, except that `tool` is implicitly added as first
+#       element.
+#
+#   depfile
+#   inputs
+#   public_configs
+#   visibility   (all optional)
+#       Same meaning as for action().
+#
+# Example use:
+#
+#   compiled_action("run_my_tool") {
+#     tool = "//tools/something:mytool"
+#     inputs = [ "my_input_file.txt" ]
+#     outputs = [ "$target_gen_dir/mysource.inc" ]
+#     args = [
+#       rebase_path(inputs[0], root_build_dir),
+#       rebase_path(outputs[0], root_build_dir),
+#     ]
+#   }
+#
+# You would typically declare your tool like this:
+#   if (host_toolchain == current_toolchain) {
+#     executable("mytool") {
+#       ...
+#     }
+#   }
+# The if statement around the executable is optional. It means "I only care
+# about this target in the host toolchain". Usually this is what you want, and
+# saves unnecessarily compiling your tool for the target platform. If you
+# need a target build of your tool as well, omit the if statement.
+
+template("compiled_action") {
+  assert(defined(invoker.args), "must set 'args' in $target_name")
+  assert(defined(invoker.outputs), "must set 'outputs' in $target_name")
+  assert(defined(invoker.tool), "must set 'tool' in $target_name")
+  assert(!defined(invoker.sources),
+         "use 'inputs' instead of 'sources' in $target_name")
+
+  action(target_name) {
+    forward_variables_from(invoker,
+                           [
+                             "depfile",
+                             "inputs",
+                             "outputs",
+                             "public_configs",
+                             "testonly",
+                             "visibility",
+                           ])
+    host_tool = invoker.tool + "($host_toolchain)"
+    host_executable = get_label_info(host_tool, "root_out_dir") + "/bin/" +
+                      get_label_info(host_tool, "name")
+    deps = [ host_tool ]
+    if (defined(invoker.deps)) {
+      deps += invoker.deps
+    }
+    script = "//Meta/gn/build/run_compiled_binary.py"
+    args = [ rebase_path(host_executable, root_build_dir) ] + invoker.args
+  }
+}
diff --git a/Meta/gn/build/run_compiled_binary.py b/Meta/gn/build/run_compiled_binary.py
new file mode 100644
index 0000000000..faac565487
--- /dev/null
+++ b/Meta/gn/build/run_compiled_binary.py
@@ -0,0 +1,8 @@
+#!/usr/bin/env python3
+"""Runs a built binary."""
+
+import subprocess
+import sys
+
+# Prefix with ./ to run built binary, not arbitrary stuff from PATH.
+sys.exit(subprocess.call(['./' + sys.argv[1]] + sys.argv[2:]))
diff --git a/Meta/gn/secondary/Userland/Libraries/LibTimeZone/BUILD.gn b/Meta/gn/secondary/Userland/Libraries/LibTimeZone/BUILD.gn
index 7ff9a3c044..e2760028aa 100644
--- a/Meta/gn/secondary/Userland/Libraries/LibTimeZone/BUILD.gn
+++ b/Meta/gn/secondary/Userland/Libraries/LibTimeZone/BUILD.gn
@@ -39,11 +39,35 @@ if (enable_timezone_database_download) {
       "southamerica",
     ]
   }
+  compiled_action("generate_timezone_sources") {
+    tool = "//Meta/Lagom/Tools/CodeGenerators/LibTimeZone:GenerateTimeZoneData"
+    deps = [ ":timezone_database_files" ]
+    inputs = get_target_outputs(":timezone_database_files")
+    outputs = [
+      "$target_gen_dir/TimeZoneData.h",
+      "$target_gen_dir/TimeZoneData.cpp",
+    ]
+    args = [
+      "-h",
+      rebase_path(outputs[0], root_build_dir),
+      "-c",
+      rebase_path(outputs[1], root_build_dir),
+      "-z",
+
+      # NOTE: Coordinates file must be inputs[0]
+    ]
+    foreach(data_file, inputs) {
+      args += [ rebase_path(data_file, root_build_dir) ]
+    }
+  }
 }
 
 source_set("LibTimeZone") {
   output_name = "timezone"
-  include_dirs = [ "//Userland/Libraries" ]
+  include_dirs = [
+    "//Userland/Libraries",
+    "$target_gen_dir/..",
+  ]
   sources = [
     "Forward.h",
     "TimeZone.cpp",
@@ -54,6 +78,7 @@ source_set("LibTimeZone") {
     "//Userland/Libraries/LibCore",
   ]
   if (enable_timezone_database_download) {
-    deps += [ ":timezone_database_files" ]
+    deps += [ ":generate_timezone_sources" ]
+    sources += get_target_outputs(":generate_timezone_sources")
   }
 }