From 1e9fc80fb090e6cac37c0a281cc7845074ed1449 Mon Sep 17 00:00:00 2001
From: bugobliterator <siddharthbharatpurohit@gmail.com>
Date: Wed, 5 Jun 2024 22:14:26 +1000
Subject: [PATCH] waf: add support for generating compile_commands.json

---
 Tools/ardupilotwaf/ardupilotwaf.py | 85 +++++++++++++++++++++++++++++-
 1 file changed, 84 insertions(+), 1 deletion(-)

diff --git a/Tools/ardupilotwaf/ardupilotwaf.py b/Tools/ardupilotwaf/ardupilotwaf.py
index 1f5a628ff50d14..d3a32f62e9ab93 100644
--- a/Tools/ardupilotwaf/ardupilotwaf.py
+++ b/Tools/ardupilotwaf/ardupilotwaf.py
@@ -680,7 +680,90 @@ def options(opt):
     g.add_option('--ubsan-abort',
         action='store_true',
         help='''Build using the gcc undefined behaviour sanitizer and abort on error''')
-    
+
+
+def write_compilation_database(bld):
+    """
+    Write the compilation database as JSON
+    """
+    database_file = bld.bldnode.make_node('compile_commands.json')
+    Logs.info('Build commands will be stored in %s', database_file.path_from(bld.path))
+    try:
+        root = database_file.read_json()
+    except IOError:
+        root = []
+    compile_cmd_db = dict((x['file'], x) for x in root)
+    for task in bld.compilation_database_tasks:
+        try:
+            cmd = task.last_cmd
+        except AttributeError:
+            continue
+        f_node = task.inputs[0]
+        filename = f_node.path_from(task.get_cwd())
+        entry = {
+            "directory": task.get_cwd().abspath(),
+            "arguments": cmd,
+            "file": filename,
+        }
+        compile_cmd_db[filename] = entry
+    root = list(compile_cmd_db.values())
+    database_file.write_json(root)
+
+GEN_COMPILE_JSON = False
+
+@feature('cxxstlib')
+@before_method('process_rule')
+def dry_run_compilation_database(self):
+    if not hasattr(self, 'bld'):
+        return
+    # we don't support more than one targets at a time
+    if len(self.bld.targets.split(',')) > 1:
+        return
+    bld = self.bld
+    bld.compilation_database_tasks = []
+    # we need only to generate last_cmd, so override
+    # exec_command temporarily
+    def exec_command(bld, *k, **kw):
+        return 0
+
+    for g in bld.groups:
+        for tg in g:
+            if (not hasattr(tg, 'name')) or (tg.name not in bld.targets):
+                continue
+            try:
+                f = tg.post
+            except AttributeError:
+                pass
+            else:
+                f()
+
+            if isinstance(tg, Task.Task):
+                lst = [tg]
+            else:
+                lst = tg.tasks
+            for tsk in lst:
+                if tsk.__class__.__name__ == "swig":
+                    tsk.runnable_status()
+                    if hasattr(tsk, 'more_tasks'):
+                        lst.extend(tsk.more_tasks)
+                # Not all dynamic tasks can be processed, in some cases
+                # one may have to call the method "run()" like this:
+                # elif tsk.__class__.__name__ == 'src2c':
+                #    tsk.run()
+                #    if hasattr(tsk, 'more_tasks'):
+                #        lst.extend(tsk.more_tasks)
+
+                tup = tuple(y for y in [Task.classes.get(x) for x in ('c', 'cxx')] if y)
+                if isinstance(tsk, tup):
+                    bld.compilation_database_tasks.append(tsk)
+                    tsk.nocache = True
+                    old_exec = tsk.exec_command
+                    tsk.exec_command = exec_command
+                    tsk.run()
+                    tsk.exec_command = old_exec
+
+    write_compilation_database(bld)
+
 def build(bld):
     bld.add_pre_fun(_process_build_command)
     bld.add_pre_fun(_select_programs_from_group)