SERVER-49036 expand response files for generating the compdb from ninja

SConstruct

@@ -3902,6 +3902,13 @@ if get_option('ninja') != 'disabled':
     else:
         ninja_builder = Tool("ninja_next")
         ninja_builder.generate(env)
+        
+        ninjaConf = Configure(env, help=False, custom_tests = {
+            'CheckNinjaCompdbExpand': env.CheckNinjaCompdbExpand,
+        })
+        env['NINJA_COMPDB_EXPAND'] = ninjaConf.CheckNinjaCompdbExpand()
+        ninjaConf.Finish()
+        
 
     # idlc.py has the ability to print it's implicit dependencies
     # while generating, Ninja can consume these prints using the

site_scons/site_tools/ninja_next.py

@@ -28,6 +28,7 @@ import importlib
 import io
 import shutil
 import shlex
+import textwrap
 
 from glob import glob
 from os.path import join as joinpath
@@ -757,8 +758,8 @@ class NinjaState:
             pool="console",
             implicit=[ninja_file],
             variables={
-                "cmd": "ninja -f {} -t compdb CC CXX > compile_commands.json".format(
-                    ninja_file
+                "cmd": "ninja -f {} -t compdb {}CC CXX > compile_commands.json".format(
+                    ninja_file, '-x ' if self.env.get('NINJA_COMPDB_EXPAND') else ''
                 )
             },
         )
@@ -1117,6 +1118,27 @@ def ninja_contents(original):
 
     return wrapper
 
+def CheckNinjaCompdbExpand(env, context):
+    """ Configure check testing if ninja's compdb can expand response files"""
+
+    context.Message('Checking if ninja compdb can expand response files... ')
+    ret, output = context.TryAction(
+        action='ninja -f $SOURCE -t compdb -x CMD_RSP > $TARGET', 
+        extension='.ninja',
+        text=textwrap.dedent("""
+            rule CMD_RSP
+              command = $cmd @$out.rsp > fake_output.txt
+              description = Building $out
+              rspfile = $out.rsp
+              rspfile_content = $rspc
+            build fake_output.txt: CMD_RSP fake_input.txt
+              cmd = echo 
+              pool = console
+              rspc = "test"
+            """))
+    result = '@fake_output.txt.rsp' not in output
+    context.Result(result)
+    return result
 
 def ninja_stat(_self, path):
     """
@@ -1240,6 +1262,8 @@ def generate(env):
     else:
         env.Append(CCFLAGS=["-MMD", "-MF", "${TARGET}.d"])
 
+    env.AddMethod(CheckNinjaCompdbExpand, "CheckNinjaCompdbExpand")
+
     # Provide a way for custom rule authors to easily access command
     # generation.
     env.AddMethod(get_shell_command, "NinjaGetShellCommand")