From 656a28ebc064b7eeba7b1eee4a36a00714a84434 Mon Sep 17 00:00:00 2001
From: Carl Hetherington <cth@carlh.net>
Date: Mon, 19 Mar 2018 23:26:08 +0000
Subject: [PATCH] Support for ycmd.

---
 compile_commands.json                   |  1 +
 waf-tools/clang_compilation_database.py | 85 +++++++++++++++++++++++++
 wscript                                 |  3 +-
 3 files changed, 88 insertions(+), 1 deletion(-)
 create mode 120000 compile_commands.json
 create mode 100644 waf-tools/clang_compilation_database.py

diff --git a/compile_commands.json b/compile_commands.json
new file mode 120000
index 000000000..25eb4b2b4
--- /dev/null
+++ b/compile_commands.json
@@ -0,0 +1 @@
+build/compile_commands.json
\ No newline at end of file
diff --git a/waf-tools/clang_compilation_database.py b/waf-tools/clang_compilation_database.py
new file mode 100644
index 000000000..4d9b5e275
--- /dev/null
+++ b/waf-tools/clang_compilation_database.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python
+# encoding: utf-8
+# Christoph Koke, 2013
+
+"""
+Writes the c and cpp compile commands into build/compile_commands.json
+see http://clang.llvm.org/docs/JSONCompilationDatabase.html
+
+Usage:
+
+    def configure(conf):
+        conf.load('compiler_cxx')
+        ...
+        conf.load('clang_compilation_database')
+"""
+
+import sys, os, json, shlex, pipes
+from waflib import Logs, TaskGen, Task
+
+Task.Task.keep_last_cmd = True
+
+@TaskGen.feature('c', 'cxx')
+@TaskGen.after_method('process_use')
+def collect_compilation_db_tasks(self):
+	"Add a compilation database entry for compiled tasks"
+	try:
+		clang_db = self.bld.clang_compilation_database_tasks
+	except AttributeError:
+		clang_db = self.bld.clang_compilation_database_tasks = []
+		self.bld.add_post_fun(write_compilation_database)
+
+	tup = tuple(y for y in [Task.classes.get(x) for x in ('c', 'cxx')] if y)
+	for task in getattr(self, 'compiled_tasks', []):
+		if isinstance(task, tup):
+			clang_db.append(task)
+
+def write_compilation_database(ctx):
+	"Write the clang compilation database as JSON"
+	database_file = ctx.bldnode.make_node('compile_commands.json')
+	Logs.info('Build commands will be stored in %s', database_file.path_from(ctx.path))
+	try:
+		root = json.load(database_file)
+	except IOError:
+		root = []
+	clang_db = dict((x['file'], x) for x in root)
+	for task in getattr(ctx, 'clang_compilation_database_tasks', []):
+		try:
+			cmd = task.last_cmd
+		except AttributeError:
+			continue
+		directory = getattr(task, 'cwd', ctx.variant_dir)
+		f_node = task.inputs[0]
+		filename = os.path.relpath(f_node.abspath(), directory)
+		entry = {
+			"directory": directory,
+			"arguments": cmd,
+			"file": filename,
+		}
+		clang_db[filename] = entry
+	root = list(clang_db.values())
+	database_file.write(json.dumps(root, indent=2))
+
+# Override the runnable_status function to do a dummy/dry run when the file doesn't need to be compiled.
+# This will make sure compile_commands.json is always fully up to date.
+# Previously you could end up with a partial compile_commands.json if the build failed.
+for x in ('c', 'cxx'):
+	if x not in Task.classes:
+		continue
+
+	t = Task.classes[x]
+
+	def runnable_status(self):
+		def exec_command(cmd, **kw):
+			pass
+
+		run_status = self.old_runnable_status()
+		if run_status == Task.SKIP_ME:
+			setattr(self, 'old_exec_command', getattr(self, 'exec_command', None))
+			setattr(self, 'exec_command', exec_command)
+			self.run()
+			setattr(self, 'exec_command', getattr(self, 'old_exec_command', None))
+		return run_status
+
+	setattr(t, 'old_runnable_status', getattr(t, 'runnable_status', None))
+	setattr(t, 'runnable_status', runnable_status)
diff --git a/wscript b/wscript
index 6a4854052..2583d400a 100644
--- a/wscript
+++ b/wscript
@@ -41,7 +41,7 @@ print 'Version: %s' % VERSION
 def options(opt):
     opt.load('compiler_cxx')
     opt.load('winres')
-
+    
     opt.add_option('--enable-debug',      action='store_true', default=False, help='build with debugging information and without optimisation')
     opt.add_option('--disable-gui',       action='store_true', default=False, help='disable building of GUI tools')
     opt.add_option('--disable-tests',     action='store_true', default=False, help='disable building of tests')
@@ -63,6 +63,7 @@ def options(opt):
 
 def configure(conf):
     conf.load('compiler_cxx')
+    conf.load('clang_compilation_database', tooldir=['waf-tools'])
     if conf.options.target_windows:
         conf.load('winres')
 
-- 
2.30.2