cxxmodules: return failure from the collator when private usage is found

1 files changed, 7 insertions, 1 deletions

diff --git a/Source/cmGlobalNinjaGenerator.cxx b/Source/cmGlobalNinjaGenerator.cxx
index 22fd90d..b74ba37 100644
--- a/Source/cmGlobalNinjaGenerator.cxx
+++ b/Source/cmGlobalNinjaGenerator.cxx
@@ -2719,7 +2719,9 @@ bool cmGlobalNinjaGenerator::WriteDyndepFile(
 
     // Insert information about the current target's modules.
     if (modmap_fmt) {
-      auto cycle_modules = CxxModuleUsageSeed(locs, objects, usages);
+      bool private_usage_found = false;
+      auto cycle_modules =
+        CxxModuleUsageSeed(locs, objects, usages, private_usage_found);
       if (!cycle_modules.empty()) {
         cmSystemTools::Error(
           cmStrCat("Circular dependency detected in the C++ module import "
@@ -2727,6 +2729,10 @@ bool cmGlobalNinjaGenerator::WriteDyndepFile(
                    cmJoin(cycle_modules, R"(", ")"_s), '"'));
         return false;
       }
+      if (private_usage_found) {
+        // Already errored in the function.
+        return false;
+      }
     }
 
     cmNinjaBuild build("dyndep");