SERVER-67122 Add warning when requesting a module that doesn't exist or when loading legacy ninja module

(cherry picked from commit 7da265df0f82719bc642fc0e28718780ebd7c9b2)
(cherry picked from commit 5a407c480493ec4dfd9c18d2c94d6238f0fba36c)
(cherry picked from commit b90f5c38ff9101a806ba35384aec59f8e24b9eb5)

2 files changed, 35 insertions, 7 deletions

diff --git a/SConstruct b/SConstruct
index 0e784010ae5..5e64f637e37 100755
--- a/SConstruct
+++ b/SConstruct
@@ -2261,13 +2261,25 @@ if get_option("system-boost-lib-search-suffixes") is not None:
 # discover modules, and load the (python) module for each module's build.py
 mongo_modules = moduleconfig.discover_modules('src/mongo/db/modules', get_option('modules'))
 
-if get_option('ninja') != 'disabled':
-    for module in mongo_modules:
-        if hasattr(module, 'NinjaFile'):
-            env.FatalError(textwrap.dedent("""\
-                ERROR: Ninja tool option '--ninja' should not be used with the ninja module.
-                    Remove the ninja module directory or use '--modules= ' to select no modules.
-                    If using enterprise module, explicitly set '--modules=<name-of-enterprise-module>' to exclude the ninja module."""))
+has_ninja_module = False
+for module in mongo_modules:
+    if hasattr(module, 'NinjaFile'):
+        has_ninja_module = True
+        break
+
+if get_option('ninja') != 'disabled' and has_ninja_module:
+    env.FatalError(
+        textwrap.dedent("""\
+        ERROR: Ninja tool option '--ninja' should not be used with the ninja module.
+            Using both options simultaneously may clobber build.ninja files.
+            Remove the ninja module directory or use '--modules= ' to select no modules.
+            If using enterprise module, explicitly set '--modules=<name-of-enterprise-module>' to exclude the ninja module."""
+                        ))
+
+if has_ninja_module:
+    print(
+        "WARNING: You are attempting to use the unsupported/legacy ninja module, instead of the integrated ninja generator. You are strongly encouraged to remove the ninja module from your module list and invoke scons with --ninja generate-ninja"
+    )
 
 # --- check system ---
 ssl_provider = None
diff --git a/buildscripts/moduleconfig.py b/buildscripts/moduleconfig.py
index b31a9dbf8db..b4d0bba0490 100644
--- a/buildscripts/moduleconfig.py
+++ b/buildscripts/moduleconfig.py
@@ -33,16 +33,26 @@ import os
 
 
 def discover_modules(module_root, allowed_modules):
+    # pylint: disable=too-many-branches
     """Scan module_root for subdirectories that look like MongoDB modules.
 
     Return a list of imported build.py module objects.
     """
     found_modules = []
+    found_module_names = []
 
     if allowed_modules is not None:
         allowed_modules = allowed_modules.split(',')
+        # When `--modules=` is passed, the split on empty string is represented
+        # in memory as ['']
+        if allowed_modules == ['']:
+            allowed_modules = []
 
     if not os.path.isdir(module_root):
+        if allowed_modules:
+            raise RuntimeError(
+                f"Requested the following modules: {allowed_modules}, but the module root '{module_root}' could not be found. Check the module root, or remove the module from the scons invocation."
+            )
         return found_modules
 
     for name in os.listdir(module_root):
@@ -66,11 +76,17 @@ def discover_modules(module_root, allowed_modules):
                 if getattr(module, "name", None) is None:
                     module.name = name
                 found_modules.append(module)
+                found_module_names.append(name)
             finally:
                 fp.close()
         except (FileNotFoundError, IOError):
             pass
 
+    if allowed_modules is not None:
+        missing_modules = set(allowed_modules) - set(found_module_names)
+        if missing_modules:
+            raise RuntimeError(f"Failed to locate all modules. Could not find: {missing_modules}")
+
     return found_modules