waf: add clang compilation database support

scripts/waflib/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)

wscript

@@ -54,7 +54,7 @@ def configure(conf):
 	# TODO: wrapper around bld.stlib, bld.shlib and so on?
 	conf.env.MSVC_SUBSYSTEM = 'WINDOWS,5.01'
 	conf.env.MSVC_TARGETS = ['x86'] # explicitly request x86 target for MSVC
-	conf.load('xcompile compiler_c compiler_cxx gitversion')
+	conf.load('xcompile compiler_c compiler_cxx gitversion clang_compilation_database')
 	if sys.platform == 'win32':
 		conf.load('msvc msvs')